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• AMF inoculation improve watermelon seedlings growth. • AMF inoculation improve watermelon essential nutrients assimilation and absorption. • AMF regulate the expression of N, P and K transporter genes in watermelon. • AMF regulate the expression of auxin and abscisic acid related genes. Arbuscular mycorrhizal fungi (AMFs) and plants have a symbiotic relationship that facilitates nutrient accumulation for plant development and productivity. However, the molecular mechanism through which AMF controls the growth and development of plants is still largely unknown. In this study, the physiological and transcriptional responses of watermelon seedlings with and without AMF inoculation were compared. AMF inoculation improved the assimilation and absorption of potassium, phosphorus, and nitrogen. When inoculated, watermelon development was considerably greater than that in the absence of inoculation. Several differentially expressed genes (DEGs) were identified after 64 days after AMF inoculation. Specifically, the metabolic and signal transduction pathways exhibited an abundance of key DEGs. Inoculated watermelons resulted in 2259 DEGs involved in photosynthesis, chlorophyll b iosynthesis, hormone biosynthesis, and nutrient transporters. Based on these results, it appears that AMF may enhance seedling growth and nutrient accumulation by stimulating gene expression. Notably, inoculation affected auxin-responsive proteins, auxin response factors, auxin-induced proteins, auxin-mediated proteins, and auxin transporter-like proteins, all of which are components of the auxin signalling pathway. The physiological and molecular analyses in this study may shed light on the underlying mechanism by which AMF affects the growth and development of watermelon. [ABSTRACT FROM AUTHOR]

The mud crab Scylla paramamosain is a major marine crab species for aquaculture in the southern coastal regions of China. This study investigated the differences in the quality of low-salt cultured and wild mud crabs and the the salinity tolerance and growth performance of their offspring. Ovarian development and fatty acid and amino acid compositions in the hepatopancreas and ovaries of mature low-salt and wild mud crabs were compared. The gonadosomatic index was significantly lower, but the hepatopancreatic index was significantly higher in the low-salt mud crab than in the wild mud crab. The contents of C18:1, C22:6n3 (DHA), DHA/EPA, and n-3/n-6 fatty acids in the ovaries and hepatopancreas of the low-salt mud crab were significantly higher than those of the wild mud crab. Except for proline in the hepatopancreas of the low-salt group, there were no significant differences in amino acids in the ovaries and hepatopancreas between the two groups. Although the survival rate of larval mud crabs in the low-salt mud crab was significantly higher than that in the wild mud crab when the salinity was 24‰, there was no significant difference in the juvenile survival between the two groups. However, the survival rate of larval and juvenile mud crabs in the low-salt group was significantly higher than in the wild group when the salinity was 5 ‰ and 3 ‰, respectively. The final body weight, average weight, weight gain, and specific weight gain rate of male and female offspring in the low-salt group were significantly higher than in the wild group. However, the weight gain and specific growth rate of male offspring in the low-salt group in September–October were significantly lower than those of male mud crabs in the wild group. This study indicates that the mud crab can be domesticated for culture and breeding at low salinity. • The fatty acid accumulation in the ovaries and hepatopancreas of Scylla paramamosain was superior at low salinity. • The offspring of Scylla paramamosain at low salinity could adapt to sudden salinity drops and had better growth performance. • Scylla paramamosain adapted to low salinity showed a stable inheritance in offspring. [ABSTRACT FROM AUTHOR]

High salinity in soil affects the strawberry production and fruit quality. Auxin-primed plants have enhanced responses to soil salinization. In this study, we report that exogenous application of IAA can partially relieve stress responses of strawberry seedlings. Cytological analysis showed that the ultrastructure of root tip and leaf cells in strawberry seedlings were altered under high salinity condition, which was partially recovered after the application of IAA. The study showed that the ultrastructure of root tip and leaf cells in strawberry seedlings were altered under salt stress condition, which was partially recovered after the application of IAA. Exogenous IAA ameliorated deleterious effects on seedling growth under salinity were attributed to accelerated Na+ fluxes, decreased the contents of Na+ to maintain the ion homeostasis, protect root growth, and promote the absorption of nutrients for improved photosynthetic efficiency in strawberry. • IAA attenuates NaCl-induced structural damage in roots. • IAA alleviates NaCl-induced root activity and nutrient accumulation. • Exogenous application of IAA can alleviate Na + accumulation in leaves under NaCl treatment indirectly. • IAA inhibits NaCl-induced oxidative stress. [ABSTRACT FROM AUTHOR]

Soil salinization has become a prominent obstacle in diverse arid and semi-arid region damaging agricultural productivity globally. From this perspective, present investigation was aimed to compare the potential compatible consortium of bio-inoculants for improving Plant Growth Promoting (PGP) attributes, anti-oxidative enzymes, grain yield and profitability of Vigna radiata in saline soil conditions. A total of 101 rhizobacterium isolated from salt affected regions of Punjab, India were screened for their ability to induce salt tolerance, multifunctional PGP traits and antagonistic activities. The 16S rRNA sequencing identified the strains LSMR-29 and LSMRS-7 as Pseudomonas flourescens and Enterococcus hirae , respectively. In-vitro compatible halo-tolerant dual inoculant (LSMR-29 + LSMRS-7) as bio-inoculants mitigated salt stress in Vigna radiata (spring mungbean) seedling with improved seed germination, biomass and salt tolerance index together with the presence of nif H, acds , pqq and ipdc gene under salinity stress as compared to single inoculants. Further, the potential of single and dual bio-inoculants were also exploited for PGP attributes in pot and field experiments. Results indicated that a significant improvement in chlorophyll content (2.03 fold), nodulation (1.24 fold), nodule biomass (1.23 fold) and leghemoglobin content (1.13 fold) with dual inoculant of LSMR-29 + LSMRS-7 over the LSMR-29 alone. The concentrations of macro & micronutrients, proline, soil enzyme activities i.e. soil dehydrogenase, acid & alkaline phosphatases and antioxidant enzymes such as superoxide dismutase, catalase and peroxidase also found to be high for LSMR-29 + LSMRS-7 as compared to un-inoculated control. The high grain yield thereby leading to Benefit: Cost (B: C) ratio at field scale was indicative of the commercial use bio-inoculants under salt affected Vigna radiata (spring mungbean) to improvement of productivity and soil health. The current finding reveals a co-inoculation of halo-tolerating Pseudomonas fluorescens and Enterococcus hirae containing ACC deaminase could prove to be novel approach for inducing salt tolerance and improving productivity of Vigna radiata (spring mungbean). [Display omitted] • Potential strains LSMR-29 & LSMRS-7 increased abiotic tolerance and colonization abilities. • Pseudomonas fluorescens and Enterococcus hirae employed as bio-stimulants. • Multifunctional PGP activities mitigate agricultural stress were summarized. • Using bio-stimulants is a sustainable and promising approach to enhance crop production. • It is novel strategy for inducing salt tolerance, improving yield and soil health. [ABSTRACT FROM AUTHOR]

• Number of autophagosomes in nutrient storage cells increases during gametogenesis. • Number of autophagosomes in nutrient storage cells in females is higher than in males. • No destruction of nutrient storage cells was observed during gametogenesis. In oysters, nutrients are stored in a special type of cells referred to as vesicular-connective tissue cells (VCT-cells). These cells accumulate and provide nutrient to satisfy various needs of the organism, including gametogenesis. During the annual reproductive cycle, VCT-cells pass through a series of changes in their morphology associated with nutrients mobilization for developing germ cells. The results presented here show an approximately 33–35% increase in the number of autophagic vesicles in cytoplasm of VCT-cells in the gonadal area of C. gigas during the stage of active gametogenesis as compared to the resting stage of reproductive cycle. No destruction of VCT-cells due to autophagy or any other factors was observed, both in males and females. Our results indicate that autophagy does increase in VCT-cells of C. gigas and plays a certain role in nutrient mobilization from these cells. [ABSTRACT FROM AUTHOR]

Highlights • The mode of nutrient accumulation and alteration at molecular level induced by the excess nutrient stress in tomato were studied. • The ICP-MS was used to analyze mineral ions in root zone solution and nutrients uptake by tomato plants. • iTRAQ-based proteomic analysis was conducted to identify proteome changes in tomato roots. • The peat-vermiculite substrates generally enhanced Ca uptake but reduced P uptake by plants, when compared to both coir and water culture. • A total of 358 differentially abundant proteins (DAPS) were identified, including 11 mineral ion binding and transport related proteins. Abstract The gradually accumulation of nutrients in organic substrates during growing season may have adverse effects on plant development. This study was conducted to determine the mode of nutrient accumulation and alteration at molecular level induced by the excess nutrient stress in tomato. The ICP-MS was used to analyze mineral ions in root zone solution and nutrients uptake by tomato plants; and iTRAQ-based proteomic analysis was conducted to identify proteome changes in tomato roots. Coir and peat-vermiculite were used in substrate treated experiments. Results showed that the content of K+ was higher in coir than in peat-vermiculite whereas it was the opposite for Ca2+. The concentrations of NO 3 −, SO 4 2- and Mg2+ were significantly higher in peat-vermiculite and coir substrates than in water culture. The peat-vermiculite substrates generally enhanced Ca uptake but reduced P uptake by plants, when compared to both coir and water culture. Compared to water culture, functional annotation analysis of the root proteome revealed that the excess nutrient accumulation induced complex proteomic alterations involved in mineral ion binding and transport. A total of 358 differentially abundant proteins (DAPS) were identified, including 11 mineral ion binding and transport related proteins, such as calmodulin-like protein and nitrate transporter 3.2 under peat-vermiculite and coir cultivations. RT-qPCR was used to validate nine genes encoding DAPS. We believe that these indicators will contribute to a better control of soilless culture systems and a waste reduction in production of tomatoes. [ABSTRACT FROM AUTHOR]

Highlights • Seed development was divided into rapid growth, slow growth, and maturation periods. • Seed growth and nutrient accumulation were improved during slow growth and maturation periods. • Improved seed growth and nutrient accumulation increased seed yield. • The expression of FAD genes were promoted during slow growth and maturation periods. • Promoted expression of FAD genes increased UFAs content. Abstract Seed yield and nutritional quality are dependent on seed development in oil crops. In a previous study, we showed that light shading improved seed yield and quality in oilseed peony, but the underlying mechanisms driving light shading impacts on seed yield and nutritional quality as mediated through seed development remain unclear. To develop an understanding of these mechanisms, oilseed peony trees were shaded by different density polyethylene nets starting at 28 days after pollination (DAP) and continuing until harvest. The seed volume, weight, and nutritional quality parameters, as well as the expression of genes related to the synthesis of unsaturated fatty acids (UFAs), were examined at 14-day intervals. Results showed that hundred-seed volume (V h), fresh weight (W f), and dry weight (W d) increased by 8.2, 15.2, and 33.0 times, respectively, from 14 to 70 DAP. During the same period, the contents of starch, soluble protein, crude oil, and UFAs increased by 2.8, 3.7, 20.4, and 21.1 times, respectively. From 71 to 98 DAP, V h , W f , and W d increased by 4.1, 5.4, and 20.8%, respectively. During this period, the contents of soluble protein, crude oil, and UFAs increased by 36.8, 51.4, and 49.5%, respectively. From 99 to 112 DAP, V h , W f , and W d slightly increased, and the content of soluble protein increased by 25.2%. In contrast, the contents of soluble sugar, starch, and crude oil decreased by 28.3, 15.1, and 6.3%, respectively. Thus, seed development of oilseed peony can be divided into three periods of rapid growth (before 70 DAP), slow growth (71–98 DAP), and maturation (99–112 DAP). At 98 DAP, light shading increased the content of soluble sugar by 8.3%. At 112 DAP, light shading increased V h , W f , W d , the content of crude oil, and UFAs by 6.9, 8.3, 8.3, 6.6, and 9.6%, respectively. The expression level of FAD 2 in peony seed was up-regulated by 87.1 and 219.3% at 98 and 112 DAP, respectively. The expression level of FAD 8 was up-regulated by 10.8, 71.7, 162.1, and 371.3% at 70, 84, 98, and 112 DAP, respectively. The expression level of SAD was up-regulated by 53.5 and 150.3% at 98 and 112 DAP, respectively. It is thus concluded that light shading significantly improved seed yield and nutritional quality parameters via increased seed growth and the expression of fatty acid desaturase genes during the slow growth and the maturation periods of seed development. [ABSTRACT FROM AUTHOR]

• Nutrient changes in Z. bungeanum fruit during development studied. • Fruit enlargement and seed development critical for high nutrient requirements. • Nutrient accumulation in mature fruit: Ca > K > N > Mg > P > Fe > Mn > Zn > Cu. • Increased nutrient absorption by seeds during development. • Higher nutrient content and accumulation in seeds than other parts. Learn about the dynamic changes of mineral nutrients in fruit is important to make effective fertilization measures during the fruit development. The content and accumulation of mineral nutrients (included N, P, K, Ca, Mg, Fe, Mn, Cu and Zn) in fruit (included pericarp, seed and whole fruit) of Zanthoxylum bungeanum 'Hanyuan' were measured during the development to explore nutrient requirements and allocation. The changes of nutrient contents and accumulation in fruit of Z. bungeanum 'Hanyuan' showed a similar trend. A temporary increase was observed in the content of N, P, Mg, Mn and Cu after blooming (AF). Subsequently, all nutrient contents declined rapidly during the fruit enlargement stage and a slight decrease during the seed formation stage, while the nutrient contents remained relatively stable in the other stages. The nutrient accumulation increased the most rapidly during the fruit enlargement and seed development stages, and there was a highly significant linear correlation between the fruit nutrient accumulation and dry weight (P < 0.05). Except for N and Mn, the content and accumulation of other nutrients were higher in the seed than that in the pericarp. Furthermore, the nutrient accumulation in fruit at maturity (115 d AF) ranked as Ca > K > N > Mg > P > Fe > Mn > Zn > Cu. Both the fruit enlargement (15–39 d AF) and seed development (57–86 d AF) stages are crucial periods for nutrient requirements. The nutrient absorption by the seed was increased, and nutrient accumulation in the pericarp tended to slow down or remained relatively stable during the seed development stage. [ABSTRACT FROM AUTHOR]

Codonopsis lanceolata is widely cultivated and consumed in China, Korea, and Japan because of its beneficial effects on health; it is an effective antioxidant and reduces the risks of diabetes, obesity, and cancer. The effects of C. lanceolata on human health are similar to that of selenium (Se). Hence, the aim of this study was to determine whether Se application could increase Se content in C. lanceolata and enhance its beneficial effects on human health. Pot experiments were conducted, and sodium selenite was applied to evaluate the effects of Se application (0, 0.5, 1.0, 1.5, and 2.0 mg Se kg −1 soil) on C. lanceolata . The biomass of C. lanceolata increased and was the highest when treated with 1.0 mg Se kg −1 soil, but after this level, there was a decrease in C. lanceolata biomass. Compared with the corresponding organs of the control group, Selenium accumulation in stems, leaves and fruits significantly increased with Se levels increasing, the highest values appeared at 1.0 mg Se kg −1 soil level for roots and fruits, and at 1.5 mg Se kg −1 soil level for stems and leaves, respectively. Selenium application increased N, P, and K accumulation, and altered the distribution of N and K, but not of P. Compared to the control, at 1.0 mg Se kg −1 soil level, the contents of polysaccharide, total flavonoid, total saponin increased significantly, thereby enhancing the health benefit of C. lanceolata ; the contents of protein, total amino acid and essential amino acid increased significantly, thereby enhancing the nutritional quality of C. lanceolata ; the contents of Se and Zn increased concurrently, suggesting the suitability of simultaneous biofortification with Zn and Se. Furthermore, the highest concentration of Se in C. lanceolata root (5.93 μg g −1 dry weight) was considered to be safe for human consumption. Approximately 12 g (dry weight) of C. lanceolata root treated with 1.0 mg Se kg −1 soil is sufficient to fulfill the daily human requirement of Se. In conclusion, C. lanceolata is a good candidate for Se biofortification, and 1.0 mg Se kg −1 soil is the optimum. [ABSTRACT FROM AUTHOR]

The adverse effects of the use of wastewater can vary, and depend on several factors, possibly causing an accumulation of toxic minerals in the soil, making it necessary to evaluate its effect when used in the irrigation of crops. The aim of this study was to evaluate changes that take place in the soluble salts and organic matter fractions of the soil, and in the growth of plants of the BRS 321 cultivar of the sunflower ( Helianthus annuus L.) cultivated in soil of a sandy texture and irrigated with wastewater obtained from oil extraction and treated by filtration and reverse osmosis. Soil samples were collected from the same area after each of the three periods of cultivation, and measurements taken of pH, electrical conductivity (EC), Na, Cl, Mg, Ca, K, HCO 3 − , Cl − , metals (Ag, As, B, Ba, Cd, Co, Cr 3+ , Hg, Ni and Pb) and organic fractions. The plants were evaluated for growth, the accumulation of root and shoot biomass, and achene production. It was found that salt concentrations and EC increased when the soil was irrigated with water treated by filtration, as did the pH, irrespective of the type of water used. Only the C of the fulvic acid fraction in the surface layer was affected by the type of water, resulting in a smaller content in the soil irrigated with FPW. Changes in the carbon content of the humic substances can be attributed in part to mobilisation of the organic fractions in the soil. The increase in salinity and alkalinity of the soil reduced plant growth and the accumulation of plant biomass. Depending on the treatment, the re-use of wastewater from oil wells may be a good option, particularly in regions with severe and extensive drought. Treatment with reverse osmosis improved the quality of the wastewater from oil wells, but for such wastewater to be used, the cumulative effects must be assessed, as alkalisation was seen to have occurred even in a sandy soil. [ABSTRACT FROM AUTHOR]

The changes in distribution and turnover of organic matter and nutrients were measured over a 34 year period in two small catchments planted to radiata pine in NSW. Catchment (eucalypt to pine) was cleared of native Eucalyptus regrowth, approximately 60 years old, and planted to radiata pine and compared to a catchment retained to native forest (Catchment 5-retained eucalypt reported by Turner and Lambert, 2016). Plots were established prior to clearing, measured and sampled and then the same plots were re-established after replanting and analysed using the same methodologies. When the radiata pine was 34 years old it had accumulated 206 Mg C ha −1 , compared to 53 Mg C ha −1 in the biomass and litter of the mature eucalypt at time of clearing. The greater biomass was partly attributed to the greater soil rooting depth as a result of deep ripping. Except for nitrogen, for which there was a net increase in the radiata pine, no differences were found in the nutrient quantity of the radiata pine and eucalypt. Increases in the biomass nutrients were balanced by decreases in soil nutrients mainly deeper in the soil profile. Catchment 3 (mature pine to pine) had mature radiata pine plantation at the commencement of the study which was cleared and replanted to radiata pine. In the mature radiata pine catchment nutrient and carbon accumulations could be found in biomass. The conversion to a new rotation led to net decreases in carbon and nitrogen however nitrogen was found to be accumulating within the system. The other nutrients were found to be lower than the previous rotation and based on previous soil nutrient productivity studies it was concluded the removals would lead to a net decrease in productivity of about 8%. Water balance and NPP data were used to analyse stand level water use efficiency and it was concluded WUE was related to age and that there was no differences between species. Differences in runoff from catchment of different forest types/species were a result of interception or productivity differences. [ABSTRACT FROM AUTHOR]

Weed composition and diversity responses to fertilization, and the effects of weed-crop competition on crop yield are not well understood, despite the importance for designing weed management strategies in sustainable crop production. The aim of the study was to determine weed community shifts and weed-oilseed rape competition as influenced by different fertilizations. Field investigations were conducted at the two final growing seasons of oilseed rape, after six years of different fertilization regimes, including NPK fertilization, with 180 kg N ha-1, 60 kg P 2 O 5 ha-1 and 62 kg K ha-1; NP fertilization, no K; NK, no P; PK, no N; and control, no fertilization. Oilseed rape yield, oilseed rape and weed species biomass and nutrient uptake, as well as weed species density and diversity were examined each growing season. Different fertilization regimes led to distinct patterns in weed community composition. NPK fertilization enhanced oilseed rape yield and growth, resulting in the lowest weed density due to intensified crop-weed competition particularly for light. Intensified crop-weed competition under high fertilization favored the dominance of a few species. In contrast, nutrient omission treatments (i.e., NP, NK, PK and control) increased the abundance of some weed species that were otherwise less competitive. The weed species Beckmannia syzigachne dominated all treatments but clearly benefited from N omission, showing the highest biomass and density under PK and control treatments. It was suppressed under NP and NPK treatments in terms of absolute biomass, but represented a greater proportion of total weed biomass than other species, indicating a higher competitive ability. A further evaluation of the relative importance of different weed species in weed-crop competition revealed that the dominant weed species Beckmannia syzigachne was the most detrimental in terms of density, biomass and nutrient uptake. In contrast, the impacts of some other species (e.g., Mazus japonicus and Ixeris polycephala) was negligible in this study. Overall, the results highlighted that NPK balanced fertilization increased oilseed rape yield with improved nutrient uptake. However, the yield gain achieved did not coincide with a diverse weed community, which calls for more attention to be paid on biodiversity besides high crop yield. Suppression of targeted weed species that are competitive and dominant might be suggested to maintain weed diversity and mitigate yield loss. • Weed composition showed distinct patterns after 6 years of different fertilization regimes. • Balanced fertilization enhanced oilseed rape growth and reduced weed density. • Intensified crop-weed competition under high fertilization favored the dominance of a few species, leading to low weed species diversity. • High oilseed rape production did not coincide with a diverse weed community. [ABSTRACT FROM AUTHOR]

Mixed-species plantations have the potential to enhance nutrient cycling and increase the overall biomass of the stand. In this study, we evaluate the dynamics of nutrient accumulation and exports in mixed-species plantations of Eucalyptus urograndis ( Eucalyptus urophylla S. T. Blake × Eucalyptus grandis W. Hill ex Maiden) and Acacia mangium Willd. after five years of rotation. Monocultures of Eucalyptus urograndis , with or without nitrogen fertilization (120 kg N ha −1 ) (E100 and E100 + N, respectively), and of Acacia mangium (A100) were established in a randomized block experimental design. Two arrangements with these species in mixed stands were also established: one with 50% of the stand density composed by each species (E50A50; 1,111 trees ha −1 ), and one high-density system, containing double the population of each species (E100A100; 2,222 trees ha −1 ). Aboveground biomass and litter nutrient contents, nutrient retranslocation from leaves, and nutrient export through wood harvesting were measured over a full rotation. Eucalyptus in E50A50, despite having half of the population of trees (555 trees ha −1 ), accumulated the same amount of nutrients in total aboveground biomass in relation to E100, suggesting a lower nutrient limitation to the growth of Eucalyptus in this mixed stand. Conversely, Eucalyptus in E100A100 did not accumulate proportionally larger amounts of nutrients in relation to E50A50, possibly due to intra- and interspecific competition in this high-density arrangement. The deposition of N and K via litter was higher in mixed-species stands than in Eucalyptus monocultures. Also, P, Ca and Mg depositions were higher in mixed-species stands than Acacia monocultures. These results suggest higher nutrient cycling and availability in the mixtures, especially after 30 months. The retranslocation of N in Eucalyptus and Acacia leaves decreased with age. At 60 months, Eucalyptus trees in E100A100 retranslocated less N than the trees in E100, probably reflecting the higher availability of soil N in relation to E100. At this same age, the Eucalyptus trees planted in E50A50 exported less N, P, K and Mg in relation to E100. However, at stand level, mixtures exported more N due to the enrichment of this nutrient in the soil promoted by Acacia . This study shows the importance of introducing Acacia in Eucalyptus plantations to promote a positive balance of nutrients for subsequent rotations and additional ecological benefits to the ecosystem due to N 2 -fixation from Acacia trees. [ABSTRACT FROM AUTHOR]

• MC-LR caused continuous and dose-dependent Ca2+ efflux in leaves. • H+ outflow from roots and H+ inflow into leaves were enhanced under MC-LR stress. • Ion imbalance induced physical shape change and decreased organic matter synthesis. Aquatic plants play an important role in maintaining lake water status and ecosystem stability, but the effect of the cyanotoxin microcystin (MC) on ion homeostasis in aquatic plants and the resulting adverse consequences remains unclear. This study used non-invasive micro-test technology to detect the effect of MC-LR on homeostasis of calcium (Ca2+) and hydrogen ions (H+) in Vallisneria natans (Lour.) Hara, and examined the relationship between ion homeostasis and physiological indicators. Results showed that 1) MC-LR was enriched in V. natans tissues, with greater absorption in roots than in leaves, and 2) MC-LR induced a sustained and dose-dependent Ca2+ efflux from leaves and recoverable Ca2+ efflux from roots. Although H+-ATPase of leaves and roots was activated by MC-LR, the effluent of H+ from roots and influent of H+ into leaves was enhanced. By affecting the homeostasis of Ca2+ and H+, MC-LR directly or indirectly affected accumulation of nutrients essential for maintaining normal growth: accumulation of nitrogen, magnesium, phosphorus, calcium, iron, and zinc decreased in leaves; calcium, magnesium, and zinc decreased in roots; and potassium showed an increase in both leaves and roots. Microscopy revealed MC-LR results in leaf swelling and reduced accumulation of protein and starch, presumably due to changes in nutrient processes. In addition, efflux of Ca2+ and reduced accumulation of transition metals resulted in decreased ROS levels in leaves and roots. The disruption of ionic homeostasis in aquatic plants can be caused by as small a concentration as 1 μg/L MC-LR, indicating potential ecological impacts caused by microcystin need greater attention. [ABSTRACT FROM AUTHOR]

Biological soil crusts (BSCs) are communities of bryophytes, lichens, bacteria, and fungi and are the primary colonizing communities in early successional landscapes. In early ecosystem development BSCs often improve the physical and chemical conditions while also promoting soil microbial communities. Although BSCs are considered ecosystem engineers in many early successional environments, the links between BSC functional processes and their developmental stage are unclear, especially in landscapes recovering from anthropogenic disturbances. In this study we examined natural BSC development over a 30-year chronosequence on two mining impacted landscapes in both boreal and arctic regions of Canada. Using High Throughput Sequencing (HTS), we found similar ubiquitous ruderal bryophytes and bacteria species common at both study areas, but significant differences in lichen and fungal community structure between the two locations. In addition, community assembly of BSC macro (bryophytes and lichens) and micro (bacteria and fungi)-phyla changed over the first 30 years of recovery at both mine sites, however, these changes were unique to each study location. We observed nutrient accumulation in the crust layer but did not find clear trends in available nutrients or gas flux over time. Instead, changes in our functional measurements were associated with colonization by specific BSC species. Further, the bacterial community at both mines seemed to be responding to changes in the bryophyte communities as they developed over time. This suggests that the establishment of bryophyte communities in early succession may be driving micro-phyla BSC community composition. A holistic view of BSCs as they develop over time in relation to their functional abilities needs further investigation, and this study provides insight into these interactions. This knowledge will improve both our understanding of early stage BSC development and our ability to develop restoration techniques to effectively restore landscapes disturbed by anthropogenic activities. • Function of BSCs in early stage is driven by compositional changes rather than time. • Bacterial communities responded to changes in bryophyte communities over time. • Bryophytes play a key role in early successional BSC community assembly. • Restoration efforts on mine sites should promote bryophyte establishment. [ABSTRACT FROM AUTHOR]

Of the EU countries, Sweden utilizes the highest proportion (10%) of its total agricultural land for horses. Horse paddocks commonly hold horses on a limited space, in the present study at a rate of 5–14 livestock units ha −1 . Thus these paddocks receive significant amounts of phosphorus (P) and nitrogen (N) through feed residues and deposition of feces and urine, which can lead to nutrient build-up in the soil. This study examined soil P and N status in different parts of horse paddocks (feeding, grazing and excretion areas) and compared it with that in adjacent, unmanaged reference soils. The paddock areas were then categorized with respect to environmental risk using the threshold concentrations of plant-available P extracted with ammonium acetate lactate solution at pH 3.75 (P-AL) and total N set by the Swedish Environmental Protection Agency. In total, seven horse farms, covering different grazing densities and soil textures representative of Swedish horse paddocks, were examined. The results showed that concentrations of water-soluble P (WSP), P-AL, and total N were highest in feeding and excretion areas within the paddocks. Weighted concentrations of soil P for the whole paddocks amounted to 2.9–10.5 mg WSP kg −1 and 35–224 mg P-AL kg −1 , and were higher than in the corresponding reference fields (0.8–4.9 mg WSP kg −1 and 17–102 mg P-AL kg −1 ). The WSP concentration in the paddocks was strongly correlated with horse density ( R 2 = 0.80*** 1 , n = 13) and P-AL with years of paddock management ( R 2 = 0.78***, n = 13). Total organic C was significantly correlated with P-AL, total P and total N in the feeding and excretion areas. The degree of soil P saturation percentage (DPS%) were important soil parameters determining WSP concentration in the paddocks ( R 2 = 0.63***, n = 110), whereas total P concentration in soils were determining P-AL concentrations ( R 2 = 0.82***, n = 112). According to Swedish environmental guidelines, two of the seven farms studied posed a high risk and three a moderate risk of extensive P leaching losses, but the risk of extensive N losses was moderate for all farms studied. As regards the specific sections of the paddock, the feeding and excretion areas had the highest risk of P leaching losses. Thus paddock soils can be high-risk areas for P leaching comprising about 3.85% of the total high-risk land area in Sweden. [ABSTRACT FROM AUTHOR]

• The physiology, transcriptomics and metabonomics of the blueberry seedlings were studied under different substrate cultivation. • There was significant difference in the growth statement of seedlings among PB, PR and BR treatments. • Multiple prenol lipids and flavonoids were significantly changed and may be closely related to blueberry growth. • VcPAL, VcHCT, VcF14G24.3 , and VcCHS were found to have high connectivity and mutual regulation. • This study provides a better understanding of the responses of blueberry seedlings to different substrate treatments and reference for blueberry soilless cultivation. The objective of this study was to evaluate the effects of soilless substrate mixtures on blueberry seedling growth under greenhouse conditions and to determine the optimal growth media for soilless blueberry (Vaccinium australe) cultivation. Trials were carried out with two-year-old blueberry seedlings from April to August 2021. Three mixed substrates (PB: peat and bark (1:1, v/v), PR: peat and rice husk (1:1, v/v), and BR: bark and rice husk (1:1, v/v)) were investigated. The results showed that the plant height, stem diameter and chlorophyll content were much higher in PB and PR than in BR. The PB and PR substrates triggered antioxidant system activity and exerted marked positive effects on blueberry seedling growth. The total flavonoid content was greatly increased in the PB group compared with the other two groups. Most element contents were greatly increased with BR compared with PB and PR. Furthermore, metabolomic and transcriptomic analyses revealed the critical responses of metabolic pathways to different substrate treatments in blueberry leaves collected in June. Overall, the metabolomic data revealed 757 metabolites with decreased levels and 1383 metabolites with increased levels. The levels of multiple prenol lipids, flavonoids, organooxygen compounds, carboxylic acids and derivatives were changed. "Flavonoid biosynthesis" was the most significantly enriched pathway and may be closely related to blueberry growth. Integrated transcriptomic and metabolomic data suggested that the expression of 4 DEGs, VcPAL, VcHCT, VcF14G24.3 , and VcCHS, was strongly correlated with flavonoid biosynthesis. This work provides insights for elucidating the mechanisms that mediate the growth adaptability of blueberry cv. 'Zhaixuan 7' in different substrates. [ABSTRACT FROM AUTHOR]

Biodiversity is central to the study of biology and research on the effects of human activities on biodiversity is becoming increasingly important as extinction levels increase. Many factors are increasing extinction levels, and continuous nitrogen application may be one of the reason driving terrestrial extinctions. Understanding the response of arable weed community assembly to fertilization is important for designing better weed management strategies in tropical rice–rice systems and also for changes in weed biodiversity. The cumulative effects of various fertilization treatments on weed species composition and diversity along with rice growth and yield were investigated in a long-term fertilizer experiment established 43 years ago in CRRI, Cuttack, India. A total of 20 weed species were observed in the study, out of which 6 species (i.e., Cyperus difformis , Cyperus tenuspica, Fimbristylis miliacea, Echinochloa colona, Oldenlandia corymbosa, Lindernia anagallis ) occurred in all treatments and remaining species occurred only in some of the treatments. Sedges were dominant in all the treatments followed by broad-leaves and grasses, high relative density of weeds was observed in control and FYM treated plots, whereas, low weed density was observed in N, NPK and NPK + FYM treatments. The indices of species diversity (species richness, Shannon–Wiener, Pielou and Simpson indices) showed linear relationships with rice yield. The balanced fertilization was more efficient at inhibiting the potential growth of weeds because of the increased growth of rice leading to competition for nutrients. Principal component analysis showed that changes in the weed community composition were due to application of P and FYM. Balance fertilization showed a positive effect on rice yield and negatively affect weeds density, although the effect is negative but balance fertilization is not resulted in species elimination or hampered biodiversity. [ABSTRACT FROM AUTHOR]

Plastic greenhouse cultivation is expanding in Korea due to increasing demand for value-added agricultural products. Potential pollutant accumulate in the root zone and may leach downward by irrigation water, causing soil and groundwater contamination. A nutrient management plan is needed to reduce the nutrient load from plastic greenhouse cultivation, although few studies have examined nutrient leaching and accumulation in the soil layers. In this study, soil, soil water, irrigation water, and weather conditions were monitored in the twice-a-year cultivation of cucumber and tomato in a plastic greenhouse for 2 years. Soil and soil water samples were analyzed every two weeks to investigate the level of nutrient accumulation and the nutrient leaching characteristics. Excessive fertilization caused nutrient accumulation in the root zone and the leaching of nutrients into the lower soil profile. The amount of phosphorus that accumulated on the soil particles of the root zone, however, did not significantly leach out with soil water movement. The electrical conductivity (EC) and NO 3 –N of the soil water gradually increased from the root zone to the lower zone and the NO 3 –N average concentration in the 150 cm soil layer was nearly equal to the maximum concentration of the fertigation water. The amount of percolation was 476.3 mm (56% of the irrigation water) in the cropping period for first cucumber cultivation (CP-C#1), 241.8 mm (53% of the irrigation water) in the cropping period for second cucumber cultivation (CP-C#2), 346.6 mm (42% of the irrigation water) in the cropping period for first tomato cultivation (CP-T#1), and 348.1 mm (51% of the irrigation water) which in the cropping period for second tomato cultivation (CP-T#2). The total NO 3 –N losses through leaching from the lower zone (60 to 150 cm soil layer) to deeper soil were 137.4 kg N ha −1 in the CP-C#1, 195.9 kg N ha −1 in the CP-C#2, 758.6 kg N ha −1 in the CP-T#1, and 54.7 N ha −1 in the CP-T#2. A significant amount of nutrients were not utilized for crop growth but instead leached in accordance with the movement of the soil water. The results of this study can serve as a baseline for the long-term monitoring of greenhouse nutrient loads and can be used in the design of new guidelines to reduce nutrient loads from plastic greenhouse cultivation. [ABSTRACT FROM AUTHOR]

In constructed wetlands for wastewater treatment, plants contribute to nutrient removal. However, plant species differ in their ability to tolerate high nutrient loads and accumulate nutrients in biomass. Growth and nutrient accumulation were investigated in two subtropical/tropical plants: melaleuca trees (Melaleuca quinquenervia) and lemongrass (Cymbopogon citratus). These were planted in 240 L mesocosms containing sand media and biochar (0 to 25% by volume). The mesocosms were loaded with tertiary effluent for 4 months, secondary clarified wastewater (SCW) for 8 months and finally septage for 9 months, a total cumulative load of 1060gN m −2 and 320gP m −2. Plant growth, including stem height and girth for melaleuca and leaf regrowth for lemongrass were monitored. Growth rates were higher (0.48 cm/day stem height; 2.22 cm/day leaf regrowth) when irrigated with septage, compared to SCW (0.32 cm/day stem height; 1.14 cm/day leaf regrowth). Plants were harvested at the end of the experiment and the biomass and nutrient content in each part determined. Both melaleuca and lemongrass had very high N and P tissue content: melaleuca leaves 23 mg/gN, 2 mg/gP; roots15mg/gN, 2.1 mg/gP; lemongrass leaves 18 mg/gN,2.2gP; roots 9.5 mg/gN, 2 mg/gP. Annual biomass and nutrient accumulation per plant was 486 g; 5.72 gN; 0.89 gP for melaleuca trees and 180 g; 2.54 gN; 0.39gP for lemongrass, a total nutrient accumulation of 33 g m −2 N and 5 g m −2 P/annum. Plant uptake accounted for 8.6%TN and 4.5%TP of load retained. Biochar amendments did not enhance growth rate nor increase N and P biomass. We postulate that effluent nutrient loads provided adequate nutrients for plant growth even in pure sand media. • Melaleuca and lemongrass were able to tolerate high nutrient loads. • Both plants had high N and P plant tissue content maximising nutrient uptake. • As a woody plant Melaleuca had high biomass and nutrient bioaccumulation. • Plant biomass and nutrient bioaccumulation in lemongrass was low compared to other herbaceous species. • Biochar additions to sand media did not increase plant growth, nutrient content, nor N and P biomass. [ABSTRACT FROM AUTHOR]

Highlights: [•] Horse feeding and excretion areas inside the paddocks are enriched with P and N. [•] Horse density and paddock age determines nutrient build-up in paddock soils. [•] Around 34,000ha of Swedish paddock soils are at risk for P and N leaching. [ABSTRACT FROM AUTHOR]

Abstract: Wind erosion and sand storms are common phenomena in semiarid steppes of northern China and could have important impact on soil nutrient balances. Vegetation coverage is one of the key factors influencing wind erosion and aeolian dust accumulation. We conducted a field experiment to investigate the effects of vegetation coverage on airborne dust accumulation and evaluated effects of dust input on the contribution of nutrients to vegetation-mulched fields. Five vegetation coverage treatments (15%, 35%, 55%, 75% and 95%) were constructed, with 0% coverage as a control. Vegetation coverage significantly affected dust accumulation in degenerated semiarid grasslands. The amounts of dust trapped by the increasing coverages were 1.7, 1.8, 2.0, 2.1 and 2.1 times of that by the control plot, respectively. The total accumulations reached a maximum of 2.5gm−2 day−1 at 75% coverage and remained stable with further increasing vegetation coverage. The particles in the dust trapped by treatment without vegetation coverage were significantly coarser than those by treatments with vegetation. In addition, the dust trapped by treatments with vegetation contained more organic carbon, nitrogen and phosphorus content than that by the control plot. This finding indicates that areas with higher vegetation coverage can obtain more nutrients by trapping airborne dust in semiarid steppes. [Copyright &y& Elsevier]

Abstract: A trial in an 11-year-old stand of radiata pine (Pinus radiata D. Don) was used to analyse the effects of accelerated loss of nutrients from the site on forest productivity and nutrient status. Raking of litter was undertaken over 14years prior to thinning, then for 2years after thinning at which time the trial was destroyed in a wind storm. The experimental design was a factorial of three main treatments: (i) removal (raking) versus nil removal of the forest floor, (ii) replacement or non replacement of nutrients to adjust for imbalances between nutrients in litter and those in the tree stem, and (iii) complete replacement (or not) of all nutrients removed in the litter. Additionally, a small trial was incorporated to address components of physical aspects of litter removal by comparing raking with ‘raking and a cover of woven plastic mesh’. Raking and nutrient additions were carried out approximately every 6months. Over the study period, the raking treatment removed about 75Mgha−1 of organic material with contained nutrients (559kgha−1 of N, 68kgha−1 of P, 323kgha−1 of Ca, 91kgha−1 of Mg, 243kgha−1 of K, 0.9kgha−1 of B) and this related to about four normal sawlog harvests or one total tree harvest. Up to the time of thinning, raking reduced basal area increment by 25% while raking together with replacement of nutrients reduced this by about 12%. Nutrient additions to unraked plots led to increases of up to 14% in basal area increment. The raking treatment reduced foliage nitrogen and this was correlated with reduced growth while other nutrients such as boron and sulphur were reduced but not to a degree to affect growth or health. The results were used to assess the effects on soil nutrient status and growth of different harvesting regimes (wood only, wood plus bark, total tree). [Copyright &y& Elsevier]

Abstract: The growth, aboveground biomass production and nutrient accumulation in black alder (Alnus glutinosa (L.) Gaertn.), silver birch (Betula pendula Roth.) and Scots pine (Pinus sylvestris L.) plantations during 7 years after planting were investigated on reclaimed oil shale mining areas in Northeast Estonia with the aim to assess the suitability of the studied species for the reclamation of post-mining areas. The present study revealed changes in soil properties with increasing stand age. Soil pH and P concentration decreased and soil N concentration increased with stand age. The largest height and diameter of trees, aboveground biomass and current annual production occurred in the black alder stands. In the 7-year-old stands the aboveground biomass of black alder (2100treesha−1) was 2563kgha−1, in silver birch (1017treesha−1) and Scots pine (3042treesha−1) stands respective figures were 161 and 1899kgha−1. The largest amounts of N, P, K accumulated in the aboveground part were in black alder stands. In the 7th year, the amount of N accumulated in the aboveground biomass of black alder stand was 36.1kgha−1, the amounts of P and K were 3.0 and 8.8kgha−1, respectively. The larger amounts of nutrients in black alder plantations are related to the larger biomass of stands. The studied species used N and P with different efficiency for the production of a unit of biomass. Black alder and silver birch needed more N and P for biomass production, and Scots pine used nutrients most efficiently. The present study showed that during 7 years after planting, the survival and productivity of black alder were high. Therefore black alder is a promising tree species for the reclamation of oil shale post-mining areas. [Copyright &y& Elsevier]

Abstract: The effects of two benthivorous fishes, common carp (Cyprinus carpio) and calbasu (Labeo calbasu), on bottom soil resuspension, water quality, nutrient accumulations, fish diet and growth of rohu (Labeo rohita) were compared. In this study, individual tanks receiving bottom soil and water from a central pond were used to more naturally simulate rohu polyculture pond conditions. Two treatment combinations were performed in triplicate for 4 weeks: 6 rohu plus 3 common carp per tank and 6 rohu plus 3 calbasu per tank. Resuspension of bottom soil, free CO2, and nitrogen and phosphorous concentrations in the water column were greater in the tanks with common carp while dissolved oxygen, pH, and total alkalinity were lower. Common carp increased the % nitrogen and % phosphorous accumulation in plankton and fish, while these nutrients were reduced in benthic macroinvertebrates and bottom soil. Gut contents of harvested calbasu contained a combination of benthic macroinvertebrates and zooplankton, rohu contained phytoplankton and zooplankton, and common carp contained almost entirely (82%) macroinvertebrates. Rohu shifted from zooplankton to phytoplankton when competition for zooplankton was higher in calbasu tanks. Since common carp preferred benthic macroinvertebrates they overlapped little with rohu for food. Common carp increased the harvesting weight and growth rate of rohu and thus had greater potential than calbasu to increase yields for rohu polyculture farmers. [Copyright &y& Elsevier]

Abstract: The effect of limited P or K supply during and after flowering on canola (Brassica napus L.) seed yields is not known. To determine the growth stage at which canola had accumulated sufficient P or K for maximum yields, we conducted two sand culture experiments in which external P (Experiment 1) or K (Experiment 2) supply was removed at four growth stages (GS 4.7; GS 4.9–5.5; GS 6.2 and maturity). Two levels of P/K supply (adequate or high) were included in each experiment. Plants had accumulated enough K by early flowering (GS 4.7) for maximum seed yields at both adequate and high K supply. Under high P supply, canola plants had accumulated sufficient P by early flowering (GS 4.7) for maximum yields. Under adequate P supply, yield loss occurred when P was removed at early flowering (GS 4.7), predominantly due to a combination of fewer siliques and fewer seeds per silique on branches. Yield loss when P supply was removed at late flowering (GS 4.9–5.5) was due to fewer seeds per silique on branches. Early P removal caused more P remobilization from vegetative organs to the seed. When K was supplied until later growth stages, K concentration in the silique walls increased under both adequate and high K supply. Stem K concentrations also increased under high supply. The results suggest that when P supply is near-limiting, canola requires a continued supply of P post-flowering for maximum seed yields. [Copyright &y& Elsevier]

Abstract: A participatory on-farm study was conducted to explore the effects of food input patterns on water quality and sediment nutrient accumulation in ponds, and to identify different types of integrated pond systems. Ten integrated agriculture–aquaculture (IAA) farms, in which ponds associate with fruit orchards, livestock and rice fields were monitored in the Mekong delta of Vietnam. Pond mass balances for nitrogen (N), organic carbon (OC) and phosphorus (P) were determined, and pond water quality and sediment nutrient accumulation were monitored. Data were analyzed using multivariate canonical correlation analysis, cluster analysis and discriminant analysis. The main variability in pond water quality and sediment nutrients was related with food inputs and water exchange rates. Water exchange rate, agro-ecological factors, pond physical properties and human waste input were major variables used to classify ponds. Classification was into: (1) low water exchange rate ponds in the fruit-dominated area, (2) low water exchange rate ponds in the rice-dominated area receiving homemade feed, and (3) high water exchange rate ponds in the rice-dominated areas receiving wastes. Pond water exchange rate was human-controlled and a function of food input patterns, which were determined by livelihood strategies of IAA-households. In the rice-dominated area with deep ponds, higher livestock and human wastes were found together with high water exchange rates. In these ponds, large organic matter loads reduced dissolved oxygen and increased total phosphorus concentrations in the water and increased nutrient (N, OC and P) accumulation in the sediments. In the rice-dominated area with wide ponds, higher homemade feed amounts were added to the ponds with low water exchange rate. This resulted in high phytoplankton biomass and high primary productivity. The contrary occurred in the fruit-dominated area, where fish were grown in shallow and narrow ponds, receiving more plant residue which resulted in lower phytoplankton biomass and lower sediment nutrient accumulation. [Copyright &y& Elsevier]

Abstract: The high productivity associated with many tropical forest plantation species has contributed to their importance in meeting the world''s growing demand for wood products. However, there is concern that their high growth rate and intensive management system might lead to site nutrients depletion. A total of 20 stands (10–28 years) of Gmelina arborea plantations in Oluwa and Omo forest reserves, Nigeria, was used to investigate the effect of Gmelina plantation development on site nutrients, aboveground productivity and nutrient accumulation. Standing biomass ranged from 81.5 to 392.1tha−1 in the youngest and oldest stands. Regardless of stand age, biomass partitioning was about 83.0, 13.5 and 3.5% to stem, branches and foliage, respectively. The size and age of trees did not significantly affect nutrient concentration in tree components. Nitrogen, Ca and Mg contents in tree tissue increased in the order of foliage>stem>branches while that of K and P increased in the order of foliage>branches>stem. Tree tissue nutrients concentration exhibited little change with stand development. Stand nutrient accumulation followed the same trend as standing biomass, with about 80% of each nutrient stored in the stem and 20% in branches and foliage. The accumulation of nutrients in stem, branches and foliage followed the order: Mg>N>Ca>P>K>Na. Though soil nutrients were slightly depleted between 10 and 19 years and re-built up afterwards, the overall effect of stand development on soil nutrients was not statistically significant, implying that the development of Gmelina plantations did not adversely affect the soil nutrient status. Consequently, productivity during the next rotation will most likely be affected by harvesting methods of current stands and management practices of the next rotation. The 20% accumulation of aboveground nutrients in branches and foliage implies that apart from the already replenished site nutrients, there will be an additional 20% nutrient input into the soil if the branches and foliage are left on the site after harvest. For long-term site quality and sustainability of production, successive plantations should be managed on 25 years rotation as lower rotation will most likely lead to steady depletion of site nutrients. [Copyright &y& Elsevier]

Abstract: Changes in biomass, nutrient accumulation and production efficiency (PE—total biomass increment per unit leaf area) were investigated in intensively managed plantations of loblolly pine (Pinus taeda L.) using an age sequence of replicated 1-, 2-, 3-, and 4-year-old stands (n =13). All stands, located on sandy Spodosols in the Coastal Plain of southern Georgia, were managed using a similar prescription that included a common genetic source, fertilization (years 1 and 3) and understory competition control. Total biomass accumulation (above- and below-ground) ranged from about 13Mgha−1 at age 2 years to 49.7Mgha−1 at age 4 years. Dry matter distributions averaged 30%, 34%, 18%, 6%, 15%, 12% and 3% for foliage, stemwood, branches, bark, taproots, coarse roots and fine roots, respectively, at age 4 years. Intensive management and rapid growth rates markedly increased soil nutrient demands, being about 15-fold higher than that documented in extensively managed stands of comparable age. Nutrient accumulations in tree biomass at age 4 years averaged 195, 22, 86, 72 and 28kgha−1 for N, P, K, Ca and Mg, respectively. Large declines (∼50%) in PE (2.6Mgha−1 year−1/unit versus 1.3Mgha−1 year−1/unit LAI) were apparent among all sites between the second and third years, with a noted recovery occurring at age 4 years. Changes in branch and taproot PE were most apparent, whereas stemwood PE did not change appreciably between ages 2 and 3 years. Correlation analyses suggested that larger declines in PE were associated with decreasing foliar nutrient levels (dilution), although changes in growth dynamics (carbon allocation) associated with advancing stand development may have also contributed. Collectively, these results suggest that intensive management may induce multiple nutrient limitations on sandy Spodosols, and that a better understanding of nutrient requirements, including macro- and micronutrient supply, will be necessary to maintain and enhance soil quality and long-term site productivity on these soils. [Copyright &y& Elsevier]

Abstract: Lepidium latifolium L. is an invasive exotic crucifer that has spread explosively in wetlands and riparian areas of the western United States. To understand the ecophysiological characteristics of L. latifolium that affect its ability to invade riparian areas and wetlands, we examined photosynthesis, chlorophyll concentration, carbohydrate partitioning and nutrient uptake in L. latifolium in response to soil flooding. Photosynthesis of flooded plants was about 60–70% of the rate of unflooded controls. Chlorophyll concentrations of flooded plants were about 60–70% of the unflooded plants during 15–50 days of flooding. Flooding resulted in an increase in leaf starch concentration, but root starch concentration was not significantly affected. However, concentrations of soluble sugar were significantly higher in both leaves and roots of flooded plants than unflooded controls. On day 50 after initial flooding, the concentrations of N, P, K and Zn in leaves of flooded plants were lower than in control plants. The concentrations of Mn and Fe in leaves of flooded plants were eight and two times those of control plants, respectively. In contrast, N, P, K and Zn concentrations of roots of flooded plants were slightly higher than in unflooded plants. The concentrations of Fe and Mn in roots of flooded plants were 15 and 150 times those of the control plants, respectively. The transport of P, K, and Zn to shoots decreased and that of Mn increased under flooding. The accumulation of N, K and Zn in roots decreased and that of Mn increased in response to flooding. The results suggested that the maintenance of relatively high photosynthesis and the accumulation of soluble sugar in roots of flooded plants are important adaptations for this species in flooded environments. Despite a reduction in photosynthesis and disruption in nutrient and photosynthate allocation in response to flooding, L. latifolium was able to survive 50 days of flooding stress. Overall, L. latifolium performed like a facultative hydrophyte species under flooding. [Copyright &y& Elsevier]

A chronosequence of Gmelina arborea Roxb. stands ranging from 1 to 6 years old was measured to document changes in growth, biomass and nutrient (N, P and K) contents for three red lateritic sites in Chhattisgarh, India. The stand''s density, survival and growth parameters (DBH, total height, crown diameter and number of branches) varied significantly with age and site. The number of stems was highest (789 trees/ha) in a 1-year-old plantation at site 3 (Kusumi) and lowest (724 trees/ha) in a 6-year-old stand at site 2 (Anandgoan). Allometric equations for stem wood, branches, leaves and roots to tree diameter at breast height were developed to estimate above ground and below ground tree biomass. The total biomass ranged from 3.9 Mg ha−1 in 1-year-old to 53.7 Mg ha−1 in 6-year-old stand. The stem wood contributed from 55.3% (site 3) to 56.3% (site 1), branch wood from 18.3% (site 2) to 19.8% (site 3), roots from 17.9% (site 3) to 18.5% (site 2) and foliage from 6.6% (site 2) to 7.0% (site 3) of the total biomass. The growth and biomass production were poor from establishment to 3 years age and it increased by 1.5–2 times as the plantation aged from 4–6 years. Nutrient accumulation in tree biomass increased with stand age, following the pattern of biomass accumulation. The total nitrogen accumulation in 6-year-old stands at three sites ranged from 212.9 to 279.5 kg ha−1 with a mean annual storage of 238.4 kg ha−1 and total K ranged from 170.8 to 220.5 kg ha−1 with a mean annual storage of 189.9 kg ha−1. Phosphorous storage was lowest which ranged from 15.0 to 19.6 kg ha−1 with a mean storage of 16.8 kg ha−1. The organic matter and nutrients in the soils improved significantly after 6 years of planting. Available N enhanced by 14.9%, 12.0% and 11.3%, K by 10.0%, 9.1% and 10.6%, whereas phosphorous declined by 2.6%, 23.0% and 20.0%, respectively, at soil depths of 0–20, 21–40 and 41–60 cm. The paper discusses the implications of whole tree harvest at 6 years age for fire/pulpwood. [Copyright &y& Elsevier]

It is well known that the availability of nutrients in red soils (equivalent to Ultisols and some of the Alfisols and Oxisols in the soil taxonomy of USA) changes after conversion of upland to irrigated rice (Oryza sativa L.) production, but long-term changes in carbon (C) and nutrients are not well documented. To characterize changes in C and nutrients in paddy fields on a Quaternary red clay (clayey, kaolinitic thermic typic plinthudults) during long-term rice cropping, we measured total C, nitrogen (N), phosphorus (P) and potassium (K), particulate organic matter (POM), N in the POM, potential mineralized N, available P, as well as other properties (pH, exchangeable cations, effective cation exchange capacity (ECEC), aggregate stability) in the plow layer (0–15 cm) of 66 rice fields with rice-cultivation time ranging from 2 to 100 years. Total C, N, and P distributions were also determined in six soil profiles with rice-cultivation times of 2, 5, 19, 48, 68, and 100 years, respectively. Significant increases in organic C, total N, and P concentrations in plow layer were found in the first 30–40 years of rice cropping, accompanied by increases in available P and potential mineralized N, exchangeable Ca, Mg, Na, base saturation, and water-stable aggregates, and decreases in total K and clay content. The C/N ratio of organic matter tended to decrease in the first 20 years of rice cropping, and remained constant at approximately 10, whereas the ratio of humic acid to fulvic acid (H/F ratio) increased gradually to about 1 after 50 years of rice cropping. Long-term rice cropping elevated C, N, and P in the plow layer and increased accumulation of C, N, and P in the subsurface soils. The results indicate: (i) long-term rice cropping improved soil fertility as evidenced by neutralization of soil acidity, and increases in ECEC, organic C content, and H/F ratio; (ii) imbalance of fertilization by high N and low K, as revealed by decreased soil K and increased soil N; (iii) long-term rice cropping caused downward movement of organic C, N, and P, which may result in environmental impacts. [Copyright &y& Elsevier]

Shortening of fallow periods due to pressure on land by population growth is a common problem throughout the forest zone of West and Central Africa. Crop yields after short-term fallows with natural vegetation are often low as a consequence of low nutrient availability to crops. Planted tree fallows may offer an alternative to natural fallows for improving short fallow-crop cycles if trees accumulate and therefore retain more nutrients in the system.Calliandra calothyrsus (Meissner) (calliandra) trees (3947 ha−1) were planted at different spatial patterns into 18 farmers’ fields in six villages, covering a wide range of soil and rainfall conditions in the forest zone of Cameroon. After 2 year of fallow calliandra tree fallows had produced between 18.9 and 25.0 Mg ha−1 of above-ground dry matter, significantly more than 14.3 and 17.3 Mg ha−1 of dry matter in 2- and 4–5-year old natural fallows, dominated by Chromolaena odorata. Planting trees in alleys and in equidistant pattern produced more biomass than planting in clusters and around the plot borders. The tree fallows accumulated above-ground on average 225 kg N ha−1, significantly more than 168 kg N ha−1 in natural fallows. Alley-planted trees accumulated more P (19 kg ha−1) than natural fallows (14 kg P ha−1), but no difference in K–Ca–Mg accumulation was found. Between 57 and 65% of the biomass in the tree fallows was stem-wood of calliandra, and 23–27% in branch wood. Nutrients in these components are unavailable for annual crops if not burned. Planting trees in clusters and dense lines around the border reduced the stem-wood mass. The stem-wood of calliandra contained on average 18% of the total fallow N, 21% of the P, 28% of the K, 16% of the Ca, and 14% of the Mg. Export of calliandra stems for firewood would, therefore, lead to substantial nutrient losses from the system. [Copyright &y& Elsevier]

In 1999, the area of abandoned agricultural land in Estonia formed 223,000 ha which is partly perspective for afforestation with grey alder, the most rapidly growing indigenous tree species. The production and nutrient (NPK) accumulation of a grey alder short-rotation plantation on former agricultural land was investigated. The production of above-ground biomass was estimated during 5 years after the establishment of the stand. In the fifth year after planting, the biomass of the above-ground part of the plantation was 15.9 t DM ha−1 and above-ground biomass production was 6.4 t DM ha−1 per year. In the fourth year after planting, the biomass of the below-ground part was 2.7 t DM ha−1, which accounted for 18% of total biomass. The biomass of the nodules was estimated at 169±76 kg DM ha−1 and the biomass of fine roots (d<2 mm) at 550±105 kg DM ha−1. Of fine roots 73.8% and all nodules were located in the upper 0–20 cm soil layer. In the fourth year after establishment, the amount of nitrogen introduced in the soil through leaf litter was 59.6 kg ha−1. As the site represented abandoned farm land, the pool of total soil nitrogen was relatively large (2.64 t ha−1 in the 0–20 cm layer). However, concerning phosphorus, the positive effect of grey alders was significant. While in the first year after planting the concentration of lactate soluble phosphorus in the 0–20 cm layer was 22.53 mg kg−1, then in the following years it was more than twice as high, varying from 47.2 to 59.7 mg kg−1. After the fifth year the amount of nitrogen accumulated in above-ground biomass was 147.1 kg ha−1, that of phosphorus 21.3 kg ha−1 and that of potassium 42.6 kg ha−1. Most of accumulated nitrogen and potassium (38.9 and 37.6%, respectively) was located in the leaves and most of phosphorus (61.0%) in the wood. [Copyright &y& Elsevier]

Here we provide a global review on nutrient accumulation rates in mangroves which were derived from sixty-nine dated sediment cores, addressing environmental and anthropogenic influences. Conserved mangroves presented nitrogen and phosphorous accumulation rates near to 5.8 ± 2.1 and 0.8 ± 0.5 g m−2 yr−1, respectively. These values were significantly lower than those observed for mangroves impacted by coastal eutrophication, which were found to bury 21.5 ± 8.6 and 17.9 ± 2.4 g m-2 yr−1, of nitrogen and phosphorous respectively. Moreover, higher nutrient accumulation rates were found in mixed mangroves as compared to monospecific forests, and higher values were noted within vegetated areas as compared to mudflats. For South America and Asia, mangroves impacted by anthropogenic activities may result in up to seventeen-fold higher nitrogen and phosphorous accumulation rates in comparison with values under conserved conditions. For Oceania, these differences may be up to fivefold higher in impacted as compared to the conserved ecosystems in this region. [Display omitted] • A research of N and P accumulation rates in mangrove sediments was performed. • Nutrient accumulation rates are higher in mangrove sediments than in bare mudflats. • Impacted mangroves presented up to four-fold higher N accumulation rates. • Impacted mangroves presented up to twenty-fold higher P accumulation rates. [ABSTRACT FROM AUTHOR]

The potential environmental risk associated with nutrient surplus after switching from rice monoculture (RM) to rice–crayfish rotation (RCR) was assessed in the Jianghan Plains in China. Nutrient surplus was achieved by surveying 32 RM and 69 RCR and determining their nutrient inputs and outputs, and the soil nutrient status for different soil properties were recorded for 0–23 years. The annual average input of N, P 2 O 5 , and K 2 O in RCR was 536, 185, and 253 kg ha−1, respectively, wherein fertilizer and feed accounted for the major fraction of the total nutrient input. For instance, they accounted 58% and 18% of N, 74% and 24% of P 2 O 5 , and 70% and 30% of K 2 O, respectively. The annual apparent surplus of N, P 2 O 5 , and K 2 O was 397, 145, and 225 kg ha−1, respectively, leading to low apparent nutrient use efficiency. Consequently, compared with RM, the total N and soil readily oxidized organic carbon in the upper soil surface (0–20 cm) for the RCR field significantly increased by 0.42–0.96 g kg−1 and 1.63–3.19 g kg−1, respectively. The available N, Olsen P, and exchangeable K of the RCR in the upper soil layer also increased significantly. In the RCR system, a significant positive linear relationship between the apparent accumulated nutrient surplus of N, P, and K elements and the total N, Olsen P, and exchangeable K present in the 0–60 cm soil profile was observed. In RCR, the soil pH in 0–60 cm soil profile and cation exchange capacity in the 0–20 cm soil layer increased as the cultivation time progressed. Nutrient accumulation in the soil not only enhanced soil fertility but also negatively influenced the environment. Therefore, several measures (e.g., new fertilization technologies, new fertilizer, legislation approaches for nutrient surplus, and technical training) should be adopted to control the nutrient surplus. Image 1 • The annual apparent surplus of N, P 2 O 5 and K 2 O were 356, 145, 225 kg ha−1 in rice-crayfish systems. • Total N and soil readily oxidized organic carbon of rice-crayfish systems in 0–20 cm soil layer significantly increased. • Nutrient accumulations existed due to excessive nutrient balance surplus in rice-crayfish rotation. The main finding: Nutrient surplus in the RCR soil enhanced nutrient accumulation, but it should be precisely monitored to avoid environmental pollution. [ABSTRACT FROM AUTHOR]

• Selective management increased the diversity of abandoned farmland. • The manipulation of competitive relationships enhanced C and nutrient accumulations. • The management of natural regeneration provided positive effects on soil quality. • The increased diversity provides the recovering of additional ecosystems function. Our aims were to describe the role of the selective management of regenerating community (RC) on the recovery of ecosystem functions in production areas of African mahoganies under mixed stands and agroforestry systems, established on abandoned farmland. A randomized block experiment was set up with the following treatments: (T1) mixed-plantation of African mahogany under conventional system (including herbicide application); (T2) mixed-plantation of African mahogany with selective conduction of RC; (T3) agroforestry system with African mahogany; (T4) agroforestry system with African mahogany with selective conduction of RC. The parameters of horizontal structure, diversity and ecological attributes of species of the regenerating community were studied. In addition, the production of aboveground biomass and nutrient stocks, soil fertility, and soil microbial activity were assessed. In T1, herbicide application (glyphosate) affected the floristic composition of the regenerating community by reducing the dominance of monocots and Pteridium arachnoideum , allowing the regeneration of other taxonomic groups of herbaceous species. In response, there was a reduction in the litter biomass stock comparing to the other treatments. The treatments with selective management of the RC (T2 and T4) produced more biomass and accumulated higher amounts of C and nutrients than the conventional treatments (T1 and T3). These treatments also allowed other shrub and tree species to overcome the ecological filter imposed by grasses and colonize the experimental area. Baccharis dracunculifolia , Vismia guianensis , Cecropia pachystachya and Inga sp. were the most important regenerating species that contributed most to the stocks of all nutrients in living aboveground biomass. Pruning and selective management in T4 increased the soil effective cation exchange, while in the T1 treatment there was a lower activity of the β-glucosidase enzyme. The selective management of RC in agroforestry systems through the manipulation of competitive relationships allowed the colonization of native tree and shrubby species that provide several additional ecosystem services, including pollination, fauna attraction, food production, pest control and environmental regulation for the agroecosystem. [ABSTRACT FROM AUTHOR]

In biofloc technology carbohydrate is added to stimulate the biofloc growth, the latter helps to improve water quality, reduce the need for water exchange and may serve as natural shrimp feed. The large diversity among possible carbohydrate sources makes the selection of a suitable carbohydrate difficult. This study investigated how corn starch addition compared to molasses addition affected water quality, biofloc and periphyton proximate composition, shrimp production parameters, diurnal fluctuations and distribution of carbon and nitrogen in whiteleg shrimp (Litopenaeus vannamei) culture system. The results showed that both corn starch and molasses addition treatments resulted in low ammonium nitrogen levels in the water. The total suspended solids and volatile suspended solids in both treatments increased over time and were not significantly different among treatments. The protein content in the dry matter of the biofloc varied from 34% to 48%, being higher in the molasses treatment. The same was observed for the protein content in the dry matter of the periphyton which ranged between 16% and 26%. The corn starch treatment resulted in significantly higher shrimp growth rate, production, average body weight, and lower FCR compared to molasses addition. Water quality was stable on a daily basis, but changed over the weeks. Carbon and nitrogen accumulations in the system were not significantly different among treatments. • The organic carbon source affects nutrient utilization efficiency in biofloc systems. • Corn starch was superior to molasses in promoting the growth of juvenile whiteleg shrimp in biofloc system. • Nutrient loss in biofloc systems, especially carbon loss, is high. [ABSTRACT FROM AUTHOR]

• We estimated rubber tree biomass and nutrient stocks over a plantation cycle. • Nutrient accumulation rate in trees peaked between 2 and 5 years after planting. • 25–36 % of the stocks of N, P and K at the clear-cut stage were accumulated at 5 years old. • Logging residues could account for 120–1126 % of the nutrient input through fertilizers over the entire rotation. Rubber trees are the main source of natural rubber (NR). The area occupied by rubber plantations rose from 3.9 million ha in 1961 to 12.5 million ha in 2018. Both the expansion of rubber plantations in marginal zones (prone to biotic and abiotic stress), and long-term rubber tree cultivation in traditional areas, raise questions about the sustainability of NR production in a context of climate change. Our study set out to gain insights into the biogeochemical cycles in rubber plantations, for a better matching of fertilizer inputs to the dynamics of nutrient demand throughout rubber tree growth. Nutrient accumulation in tree biomass is a major component of the biological cycle in tree plantations. We studied the dynamics of biomass and nutrient accumulation in two chronosequences covering the whole lifespan of a plantation in Ivory Coast managed on a sandy soil at the SAPH site, and one on a clayey soil at the SOGB site. In total, 56 trees were destructively sampled in 2-, 5-, 20- and roughly 40-year-old stands. While the use of allometric relationships is common for estimating nutrient stocks in planted forests, this study was the first to provide allometric equations predicting nutrient stocks in rubber tree components. Allometric models were applied to the inventory of 4 commercial stands, for each age at each site, to estimate stand biomass and nutrient stocks. The current annual increments of nutrient stocks in tree biomass peaked between 2 and 5 years after planting. They reached 80 kg ha-1 yr-1 for N, 14 kg ha-1 yr-1 for P and 34 kg ha-1 yr-1 for K at SAPH (53, 7, and 39 kg ha-1 yr-1 respectively at SOGB), which highlighted the importance of an appropriate fertilization schedule for young rubber trees. At the clear-cut age (38–40 years), the amounts of nutrients accumulated in tree biomass were 970 kg N ha-1, 188 kg P ha-1, 366 kg K ha-1, 941 kg Ca ha-1 and 255 kg Mg ha-1 on the sandy soil at SAPH (907,118, 629 1499, and 375 kg ha-1 respectively on the clayey soil at SOGB). Contrasting soil properties and management practices at the two sites had a much greater effect on the amounts of P, K, Ca and Mg accumulated in the trees than on N accumulation. Logging practices in rubber plantations can lead to considerable nutrient exports on poor tropical soils. Harvest residues should be distributed uniformly in the plots so that the roots of young trees can quickly gain access to the nutrients released during decomposition. [ABSTRACT FROM AUTHOR]

Selenium (Se) and zinc (Zn) are essential micronutrients that are often lacking in the diet of humans and animals, leading to deficiency diseases. Lemna and Azolla are two aquatic plants with a substantial protein content, which offer the possibility of utilizing them to remove Se and Zn from (waste)water while producing micronutrient-enriched dietary proteins and fertilizers. In this study, we explored interaction effects occurring between Se and Zn when these micronutrients are taken up by Azolla and Lemna. The two aquatic plants were grown on hydroponic cultures containing 0–5.0 mg/L of Se (Se(IV) or Se(VI)) and Zn. The Se and Zn content of the plants, growth indicators, bioconcentration factor (BCF) and Se/Zn removal efficiency from the water phase were evaluated. The results demonstrated that Se(IV) is more toxic than Se(VI) for both plant species, as evidenced by the remarkable decrease of biomass content and root length when exposed to Se(IV). Both aquatic plants took up around 10 times more Se(IV) than Se(VI) from the medium. Moreover, the Se accumulation and removal efficiency increased by 66–99% for Se(IV) and by 34–59% for Se(VI) in Lemna when increasing Zn dosage from 0 to 5.0 mg/L in the medium, whereas it declined by 13–26% for Se(IV) and 21–35% for Se(VI) in Azolla , suggesting a synergetic effect in Lemna, but an antagonistic effect in Azolla. The maximum BCF of Se in Lemna and Azolla were 507 and 667, respectively. The protein content in freeze-dried Lemna and Azolla was approximately 17%. The high tolerance and accumulation of Se and Zn in Lemna and Azolla , combined with their rapid growth, high protein content and transformation of inorganic to organic Se species upon Se(IV) exposure make Lemna and Azolla potential candidates for the production of Se(IV)- and Zn-enriched biomass that can be used as crop fertilizers or protein-rich food/feed supplements or ingredients. Accordingly, by growing the Azolla and Lemna on wastewater, a high-value product can be produced from wastewater while recovering resources. Image 1 • Interaction effects between Se and Zn by Azolla and Lemna were studied. • Se and Zn had synergetic effects in Lemna , but antagonistic effects in Azolla. • Azolla and Lemna took up around 10 times more Se(IV) than Se(VI) from the medium. • The protein content in both Lemna and Azolla was approximately 17%. • The transformation of Se(IV) to organic Se in the plants contributes to feed production systems. [ABSTRACT FROM AUTHOR]

• Nutrient balances and accumulations in newly built solar greenhouses were studied over five years. • High nutrient surpluses resulted in low use efficiency and high accumulations in soil profiles. • The accumulated nitrate in 0–2 m soil profiles averaged 1814 kg N ha−1 after five years of cultivation. • Soil nutrients and EC were increased linearly with the cultivation years. Over-application of fertilizers is very common in solar greenhouse vegetable production. Therefore, understanding nutrient balances and changes in soil is important for crop production and the environment. A five-year consecutive monitoring was conducted to investigate the nutrient balances and changes of soil properties, including soil organic matter (SOM), nutrient contents, pH and electrical conductivity (EC), in thirteen newly built solar greenhouses in the Loess Plateau. The average annual nutrient inputs from manure and mineral fertilizers were 1,871 kg N ha−1, 1,616 kg P 2 O 5 ha−1, and 1,780 kg K 2 O ha−1, with manure accounting for 60.7%, 55.1%, and 53.3% of the total nitrogen (N), phosphorus (P), and potassium (K) input, respectively. The annual nutrient apparent balances were 1354 kg N ha−1, 1492 kg P 2 O 5 ha−1 and 960 kg K 2 O ha−1, respectively. Consequently, SOM and total N significantly increased in the 0–100 cm soil profile, with average annual rates of 0.84–3.76 g C kg−1 and 0.06–0.22 g N kg−1, respectively. Nitrate N in the 0–100 cm and 0–200 cm soil profiles were significantly increased, with annual average rates of 182 kg N ha−1 and 225 kg N ha−1, respectively. Olsen P and exchangeable K significantly increased, with average annual rates of 2.3–44.1 mg P kg−1 and 10.4–63.2 mg K kg−1 in the 0–80 cm and 0–40 cm soil profiles, respectively. The significantly positive linear relationships were found among apparent accumulated balances of N, P and K and soil total N, Olsen P and exchangeable K, respectively. The pH in 0–20 cm soil significantly reduced. However, the EC in 0–100 cm soil significantly increased. In conclusion, excessive nutrient balance surpluses result in rapid nutrient accumulations in soil of newly built greenhouses, and attention should be paid to its negative effects on the environment in near future. [ABSTRACT FROM AUTHOR]