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Background: Potassium (K) is an essential nutrient for plant growth and development. However, plant fertilization ignoring the soil K level is very likely to cause excessive fertilizer use, and further arouse a series of side effects. This study investigated the response of cotton growth to different soil K levels and the uptake of major nutrients, aiming to evaluate the appropriate K supply level for cotton growth. Using a random block design with 6 soil K levels, we conducted 18 micro-zones field experiments over two continuous years. The soil available K concentration of each treatment was K1 (99.77–100.90 mg·kg−1), K2 (110.90–111.26 mg·kg−1), K3 (123.48–128.88 mg·kg−1), K4 (140.13–145.10 mg·kg−1), K5 (154.43–155.38 mg·kg−1), and K6 (165.77–168.75 mg·kg−1). Cotton nutrient contents, soil nutrient contents, accumulation and distribution of dry matter in cotton were determined, and the relationships between K content in soil and plants and dry matter accumulation were analyzed. Results: The soil K content had a significantly positive relationship with dry matter and K accumulation in cotton plants. There were significant differences in dry matter accumulation, single-plant seed cotton yield, mineral nutrient uptake and the proportion of K accumulation in reproductive organs among different soil K levels. The results showed that there was significant difference between K4 and lower K level treatments (K1 and K2), but no significant difference between K4 and higher K level treatments (K5 and K6) in dry matter, single-plant seed cotton yield, or accumulation, distribution and seed cotton production efficiency of N, P and K. Conclusion: The soil K level of K4 was able to provide sufficient K for cotton growth in our experiment. Therefore, when the soil K level reached 140.13 mg·kg−1, further increasing the soil K concentration no longer had a significant positive effect on cotton growth. [ABSTRACT FROM AUTHOR]

Adventitious root formation is a bottleneck during vegetative proliferation. Potassium (Kþ) is an essential macronutrient for plants. Kþ accumulation from the soil and its distribution to the different plant organs is mediated by Kþ transporters named Kþ transporter (KT), Kþ uptake (KUP), or high-affinity Kþ (HAK). This study aimed to identify members of the HAK gene family in apples and to characterize the effects of Kþ supply on adventitious root formation and on the expression of HAK genes and the genes that putatively control auxin transport, signaling, and cell fate during adventitious root formation. In this study, 34 HAK genes (MdHAKs) were identified in the apple (Malus x domestica 'Golden Delicious') genome. A phylogenetic analysis divided MdHAKs into four clusters (I, II, III, and IV), comprising 16, 1, 4, and 13 genes, respectively. The syntenic relationships revealed that 62.5% of the total MdHAK genes arise from genomic duplication events. Chromosome location, domain structure, motif analysis, and physico-chemical characteristics were subsequently investigated. Furthermore, the application of Kþ indicated the emergence of adventitious roots at 8 d and produced more adventitious roots at 16 d than the Kþ-free control (CK) treatment. In addition, various MdHAKs showed root-specific expression in B9 apple rootstock stem cuttings and enhanced expression during the initiation and emergence stages of adventitious root formation in response to Kþ treatment. Additionally, Kþ treatment enhanced the expression levels of MdPIN1, MdPIN2, and MdAUX1. Further data indicated that a higher expression of MdWOX11, MdLBD16, and MdLBD29 and of cell cycle-related genes contributed to the auxin-stimulated adventitious root formation in response to Kþ. [ABSTRACT FROM AUTHOR]

Potassium (K) participates in critical processes in sunflower cultivation, such as osmotic regulation and translocation of photosynthesis. However, the absorption or accumulation of this nutrient occurs differently owing to edaphoclimatic factors or between cultivars. The objective of this study was to evaluate the nutritional efficiency of sunflower cultivars as a function of different dosage K dosages in a semiarid region. To this end, two experiments were conducted in 2016 and 2017. The treatments consisted of five dosages of K at 0, 30, 60, 90, and 120 kg ha-1 K2O and four sunflower cultivars, Aguará 6, Altis 99, Multissol, and BRS 122. The experimental design was a randomized block with four replications and subdivided plots. The characteristics evaluated were agronomic efficiency, physiological efficiency, recovery efficiency, utilization efficiency, and accumulation of total K in the plant. Sunflower cultivars responded to K dosages in the two crops, with variations in efficiency parameters. Crop 2 showed better nutritional efficiency compared to crop 1. Aguará 6 showed greater nutritional efficiency than the other two crops. The use of dosages between 75 and 91 kg ha-1 of K2O provided better efficiency in K usage for the cultivars. [ABSTRACT FROM AUTHOR]

Increasing the quality and yields of maca are important goals to meet market demands. The objective of the research was to quantify the extraction of nutrients from the soil and evaluate the effect of three levels of nitrogen (N), phosphorus (P), potassium (K) and sulfur (S) on agronomic indicators of maca cultivation under field and greenhouse conditions. The experiment was conducted under the randomized complete block design with four repetitions per treatment. The levels were 240-180-210-60, 160-120-140-40 and 0-0-0-0 NPKS, respectively. Tukey's test was used for the comparison of means. Different indicators of plant growth and development were evaluated, such as plant height, hypocotyl diameter, hypocotyl weight, dry matter percentage and yield. The evaluation of nutrient extraction was evaluated according to the methodology used in the AGROLAB laboratory: Nitrogen: micro kjeldahl method. Phosphorus: Bray-Kurtz colorimetric method. Potassium: Peech's turbidimetric method. Sulfur: Massoumi's turbidimetric method. Calcium and Magnesium: volumetric method of complexometry. Among the results, significant differences were found between S levels in all the variables evaluated. No statistical differences were found in nutrient extraction due to NPKS doses. It is concluded that higher doses of NPKS increases in the values of height, hypocotyl size, hypocotyl weight and yield, except for dry matter, in maca plants are obtained. [ABSTRACT FROM AUTHOR]

Soilless culture is the most popular cultivation method in greenhouse farming and fertigation in soilless culture determines the qualitative and quantitatively yield of tomato (Solanum lycopersicum L.). The demand for plant nutrients vary with the surrounding environment, growing medium, and plant growth stages of the crops. Most recommended fertilizer dosages for greenhouse crops have been developed to match with the environmental conditions in the temperate region. This study attempted to identify the optimum potassium (K) fertilizer application rates for different growth stages of tomato grown in soilless culture under semi intensive greenhouse environment (31±2 °C daytime temperature and 75% relative humidity). Selected dosages of K for greenhouse tomato (K treatments) were compared at advancing growth stages (0.05-0.4, 0.1-0.55, 0.2-0.6 and 0.25-0.65 g/plant/day) in a replicated trial. At the end of each growth stage, plant growth parameters and leaf tissue nutrients were assessed to compare the K application rates. Based on growth parameters, marketable yield and plant nutrient contents, the optimum K fertilizer application rates for vegetative, early reproductive, middle reproductive and late reproductive growth stages of tomato were 0.1, 0.2, 0.3 and 0.35 g/plant/day, respectively. These application rates were able to maintain the plant tissue K concentrations of 2.5, 2.1, 2.5 and 2.8% at respective growth stages. Optimum K application rates identified in this study would be useful for making growth specific fertigation recommendations for greenhouse tomato grown in soilless culture under tropical conditions in order to make protected culture is more cost effective and environmental friendly. [ABSTRACT FROM AUTHOR]

Copyright of Agronomía Colombiana is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Societal Impact Statement: Oil palm is the first oil‐producing crop globally, representing nearly 20 million ha. In the recent past, oil palm cultivation has been controversial not only because of land utilisation at the expense of primary tropical forests or health concerns associated with palm oil, but also pollution caused by fertilization (including CO2 produced to synthesise fertilizers). Oil palm fields are heavily fertilized with potassium (K), and thus finding better, more parsimonious methods to monitor K nutrition is more important than ever. Here, we suggest that metabolomics and subsequent machine learning of metabolic signatures represent a promising tool to probe K requirements, opening avenues for precision agriculture in oil palm industry. [ABSTRACT FROM AUTHOR]

Chronic kidney disease (CKD) has been a global health problem in recent years. CKD patients often restrict their potassium (K) intake to avoid the high risk of hyperkalemia. In this study, quantitative K management in hydroponics was adopted to produce low K cherry-type tomato (Solanum lycopersicom L.) fruit. The total quantity of K supply per plant during the cultivation was 7.2 g (1 K), 3.6 g (1/2 K), 1.8 g (1/4 K), 0.9 g (1/8 K) and 0.6 g (1/12 K), respectively. The total fruit yield decreased to about 75% at 1/2 K and 58% at 1/12 K compared to 1 K. The fruit K content was lower in 1/4 K, 1/8 K and 1/12 K than in 1 K and 1/2 K, and the fruit from 1/8 K and 1/12 K achieved below 100 mg 100 g−1 FW of K. Total soluble solid content (Brix) was 7–8% in 1 K and 1/4 K but was lower in 1/8 K and 1/12 K. Fruit acid content decreased to 87% in 1/2 K to 70% in 1/4 K and 1/8 K, and to 57% in 1/12 K of 1 K. In conclusion, quantitative K management in hydroponics is expected to produce low K tomato fruit. Fruit K content of approximately 100 mg.100 g−1 FW was achieved when the quantity of K supply was 1/4 K and 1/8 K, with a relatively smaller effect on fruit yield, Brix and acid content. [ABSTRACT FROM AUTHOR]

Calcineurin B-like (CBL) proteins are reported to play significant roles in plant development and ion-transport regulation. Potassium shortages are a serious problem in banana cultivation. However, to date, the members of the banana CBL gene family, and their function in regulating potassium stress, remain unclear. In this study, 11 CBL genes were identified from the banana genome and grouped into four groups (Group I–IV) based on their phylogenetic relationships. The genomic features of these MaCBL genes were analyzed, focusing on their gene structures, standpat motifs, chromosomal distributions, and evolutionary history. Expression pattern analysis revealed that the MaCBLs were function-specific. Further qRT-PCR analysis indicated that the presence of MaCBL2 was indeed a response to potassium deficiency stress. The MaCBL2 gene was cloned, and sequence alignment indicated that it contained four elongation factor hand (EF-hand) domains, the conserved N-terminal myristoylation domain “MGCXXS/K(T)” and the “FPSF” motif. Subcellular location analysis showed that MaCBL2 was located in the plasma membrane, nucleus and cytoplasm. The overexpression of MaCBL2 could restore the growth of the yeast mutant R5421 on a K+ -deficient medium. The overexpression of MaCBL2 could promote the root length of transgenic seedlings on K + -deficient medium. These findings indicate that MaCBL2 was, in our study, the key gene of the CBL family in responding to potassium deficiency in bananas. Our discoveries have established a considerable basis for the further study and application of MaCBL genes. [ABSTRACT FROM AUTHOR]

A field experiment was carried out at department of agricultural microbiology, Annamalai University, Chidambaram, Tamil Nadu, India to evaluate the performance of tomato inoculated with Arbuscular Mycorrhiza (AM) and phosphate solubilizing bacteria (PSB) when the fertilizer application was reduced to 50% and 25% of the recommended fertilizer dose (RDF). The results of the study revealed that, inoculation of tomato with AM and PSB significantly increased all the parameters examined during the study. However, the best results were obtained when the seedlings were inoculated with AM followed by PSB at 50 % of the RDF as evident from 16.6% and 12.6% increase in the total plant dry weight at the respective treatments as compared to control. Similarly the concentration of nitrogen (N), phosphorus (P), and potassium (K) in the plants inoculated with AM at 50 % of the RDF was increased by 17.3, 20.6 and 23.2% followed by an increase of 2.5, 11.5, and 12.2% at PSB with 50 % RDF as compared to control. Yield of tomato was respectively increased by 9.7% and 4.4 % when inoculated with AM and PSB at 50 % of RDF as compared to control. [ABSTRACT FROM AUTHOR]

Potassium (K) is closely related to plant water uptake and use and affects key processes in assimilation and growth. The aim of this work was to find out to what extent K supply and enhanced compartmentation might improve water use and productivity when tomato plants suffered from periods of water stress. Yield, water traits, gas exchange, photosynthetic rate and biomass partition were determined. When plants suffered dehydration, increasing K supply was associated with reduction in stomatal conductance and increased water contents, but failed to protect photosynthetic rate. Potassium supplements increased shoot growth, fruit setting and yield under water stress. However, increasing the K supply could not counteract the great yield reduction under drought. A transgenic tomato line with enhanced K uptake into vacuoles and able to reach higher plant K contents, still showed poor yield performance under water stress and had lower K use efficiency than the control plants. With unlimited water supply (hydroponics), plants grown in low-K showed greater root hydraulic conductivity than at higher K availability and stomatal conductance was not associated with leaf K concentration. In conclusion, increasing K supply and tissue content improved some physiological features related to drought tolerance but did not overcome yield restrictions imposed by water stress. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is one of the most required mineral elements for plant growth, and potassium (K) plays a vital role in nitrogen metabolism, both elements being widely applied as fertilizers in agricultural production. However, the exact relationship between K and nitrogen use efficiency (NUE) remains unclear. Apple dwarf rootstock seedlings (M9T337) were used to study the impacts of different K levels on plant growth, nitrogen metabolism, and carbon (C) assimilation in water culture experiments for 2 years. The results showed that both deficiency and excess K inhibited the growth and root development of M9T337 seedlings. When the K supply concentration was 0 mM and 12 mM, the biomass of each organ, root-shoot ratio, root activity and NO3– ion flow rate decreased significantly, net photosynthetic rate (P n) and photochemical efficiency (F v/ F m) being lower. Meanwhile, seedlings treated with 6 mM K+ had higher N and C metabolizing enzyme activities and higher nitrate transporter gene expression levels (NRT1.1 ; NRT2.1). 13C and 15N labeling results showed that deficiency and excess K could not only reduce 15N absorption and 13C assimilation accumulation of M9T337 seedlings, but also reduced the 15N distribution ratio in leaves and 13C distribution ratio in roots. These results suggest that appropriate K supply (6 mM) was optimal as it enhanced photoassimilate transport from leaves to roots and increased NUE by influencing photosynthesis, C and N metabolizing enzyme activities, nitrate assimilation gene activities, and nitrate transport. [ABSTRACT FROM AUTHOR]

BACKGROUND: To understand why biochar amendment to soils has a negative effect on sap‐feeding insects on their host plants, we used the electrical penetration graph (EPG) technique to examine probing and feeding behaviors of the English grain aphid Sitobion avenae on wheat and the small brown planthopper Laodelphax striatellus on rice; their food plants were cultured in soils receiving different treatments of biochar type (derived from three different types of feedstock: wheat, corn or rice straw) by amendment rate (four levels: 0, 1.5%, 3%, or 5%). In addition, we analyzed the contents of key nutrients in the wheat plant to explore their relevance to aphid feeding activities. RESULTS: Biochar amendment to soils increased the number of events and duration of non‐probing and probing‐preparation activities while decreasing the duration of stylet penetrations in the phloem sieve by both S. avenae and L. striatellus. The effect varied depending on the biochar amendment rate in S. avenae and on both biochar type and amendment rate in L. striatellus. Biochar amendment decreased the content of sucking stimulatory nitrogen and increased that of sucking inhibitory silicon and potassium in wheat plants; this effect varied with biochar amendment rate and not with biochar type. CONCLUSION: Biochar amendment can make stylet penetration activities less effective by S. avenae and L. striatellus on their host plants. Ineffective penetration may result from the alteration in the contents of penetration‐relevant nutrients in the host plant as a consequence of biochar amendment to soils. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Copyright of Agronomía Colombiana is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this study was to investigate the effects of foliar applications of potassium and zinc on the fruit yield and quality as well as leaf nutrient concentrations of pistachio cv. 'Chrokeh'. The experiment was conducted based on a completely randomized block design with nine treatments and three replications per treatment. Treatments were three levels of K2SO4 (0, 1 and 2%) and three levels of ZnSO4 (0, 0.5 and 1%). The nutrition solutions were sprayed on trees at two times (bud swell stage and green tip stage) in 2017-2018. Based on the obtained results, nutrient treatments especially 1% K2SO4+1% ZnSO4 and 2% K2SO4+1% ZnSO4 caused a significant increase in chlorophyll a, chlorophyll b, total chlorophyll and carotenoid contents. Application of K2SO4 and ZnSO4 significantly affected concentrations of P, K, Mg, Zn, Mn and Fe in the leaves of 'Chrokeh' pistachio, whereas nutrient treatments had no significant effect on leaf concentration of N. Nutrient treatments especially 2% K2SO4+1% ZnSO4 led to significant increases in the fresh (up to 65%) and dry (up to 67%) yield when compared with the control trees. Moreover, nutrient applications had a significant effect on the percentage of splitting (an 11 % increase) and blankness (a 26% decrease). It can be concluded that foliar application of K and Zn fertilizers is necessary for obtaining better fruit yield and quality in pistachio. [ABSTRACT FROM AUTHOR]

Highlights • The amendment with a K-rich compost under drought modulated pepper fruit quality. • Plants grown with carrot compost had low carotenoids and high phenols in fruits. • Carrot compost treatment increased fruit concentrations of minerals, mainly K. • Positive relationships between fruit K, proline and phenolic compounds were found. Abstract Water availability is the most critical factor to growth and development of plants, which limits the productive potential of plants. Plants adapt to water deficits by physiological alterations, biochemical changes and osmotic adjustments. The aim of this study was to investigate the effect of soil amendment of a K-rich carrot compost on pepper (Capsicum annuum L. cv. Paco) physiology and fruit quality under drought. Furthermore, an attempted to determine the influence of these combined factors on yield and quality pepper fruits. Carrot compost (ZC) was obtained by aerobic composting from carrot wastes from packing plants and not presented phytotoxic substances that prevented germination and grown of pepper seedlings. When the vegetative stage corresponding to start of flowering was reached, half of the plants were subjected to drought conditions (moderate water stress). Results showed that the concentration of minerals, free proline, total phenols and main carotenoids (β-carotene and lycopene) in pepper fruits were significantly modified by water level and/or substrate type. Under drought, plants grown in a mixture of 35% ZC and 65% soil (ZC35) increased concentrations of minerals (mainly K) and phenols but decreased β-carotene and lycopene levels. Moreover, significant relationships between K content, phenolic compounds and free proline were highlighted. Overall, data suggest that the use of a K-rich carrot compost for growing pepper under drought could selectively modify plant metabolic activities that are involved in the accumulation of carotenoids and phenolic compounds and thus, in fruit quality. [ABSTRACT FROM AUTHOR]

Purpose: Roses are one of the ornamental species of major importance and economic value. Fertilisation programmes which maximise plant growth and quality, while minimising environmental impact are important. Here, we followed the N and K dynamics during rose development with the aim to define the nutrient demands as a basis for implementing fertigation programmes. Materials and methods: Roses with one basal break were grown in a closed hydroponic system. Destructive samples were taken to determine dry weight, N and K content. In each sample, plants were sectioned into roots, rootstock, basal break, stems and leaves from the zone of active leaves and the zone of cutting flowers, as well as the flower bud in the latter. Results: The shoots of the active leaves and cutting flowers zones exhibited a biphasic growth; dry weight, N and K increased after pruning of the zone of active leaves and the cutting flowers zone, however, in the second phase, total dry weight did not show a significant difference between the phenological phases, while the accumulation of N and K decreased throughout the entire plant. Conclusions: Our results suggest that greenhouse roses develop a dynamic and complex balance between the aerial parts of the plants and the roots for storage and/or transport of photoassimilates, N and K. The total demand for N was 411 and 799 mg per plant for the initial shoot development of the active leaf zone and cutting flowers zone, respectively. The demand for K was 149 and 106 mg per plant for both shoots, respectively. The loss of N (555 mg per plant) and K (167 mg per plant) from roses plants to the root environment implies that lower fertiliser inputs can be used as these nutrients may be re-uptaken by new emerging roots. [ABSTRACT FROM AUTHOR]

Improved P and K nutrition can enhance yield and persistence of alfalfa ( Medicago sativa L.) grown on low fertility soils, but it is unknown if the improved agronomic performance is associated with greater taproot N and C reserves. Our objective was to use cluster analysis to determine how alfalfa plant persistence is altered by P and K fertilization, and determine if changes in specific taproot C and/or N reserves were associated with alfalfa plant death. Taproots were dug and plants counted in May and December of each year and taproots analyzed for P, K, starch, sugar, amino-N, and soluble protein. K-means clustering was used to create six clusters that were subsequently compared using two-sample t -tests. Low K in herbage and taproots was associated with low yield and poor persistence of the Low and Very Low clusters and taproots of these plants generally had low starch, protein, and amino-N concentrations. Plants died primarily between May and December. Plant persistence of the low yielding, P-deficient Medium cluster was high and associated with high starch concentrations. Low amino-N concentrations in taproots may provide an early indication of potential plant death because these were evident in poor-persisting Low and Very Low clusters early in the study. [ABSTRACT FROM AUTHOR]

Potassium is the most abundant inorganic cation that constitutes up to 10% of the total plant dry weight and plays a prominent role in plant growth and development. Plants exhibit a complex but highly organized system of channels and transporters, which are involved in absorption and distribution of K+ from soil to different parts of plants. In this study, we explored the K+ transport system in chickpea genome and identified 36 genes encoding potassium channels and transporters. The identified genes were further classified on the basis of their domain structure and conserved motifs. It includes K+ transporters (23 genes: 2 HKTs, 6 KEAs, and 15 KUP/HAK/KTs) and K+ channels (13 genes: 8 Shakers and 5 TPKs). Chromosomal localization of these genes demonstrated that various K+ transporters and channels are randomly distributed across all the eight chromosomes. Comparative phylogenetic analysis of K+ transport system genes from Arabidopsis thaliana, Glycine max, Medicago truncatula, and Oryza sativa revealed their strong conservation in different plant species. Similarly, gene structure analysis displayed conservation of family-specific intron/exon organization in the K+ transport system genes. Evolutionary analysis of these genes suggested the segmental duplication as principal route of expansion for this family in chickpea. Several abiotic stress-related cis-regulatory elements were also identified in promoter regions suggesting their role in abiotic stress tolerance. Expression analysis of selected genes under drought, heat, osmotic, and salt stress demonstrated their differential expression in response to these stresses. This signifies the importance of these genes in the modulation of stress response in chickpea. Present study provides the first insight into K+ transport system in chickpea and can serve as a basis for their functional analysis. [ABSTRACT FROM AUTHOR]

Our study aims to elucidate how decreases in peatland above-ground net primary production (AG-NPP) might be explained by a network of relationships between some nutritive elements and the N:P ratios in different plant groups. We focused on three functional groups of peatland plants with different growth form: Sphagnum mosses, shrubs, and non-woody vascular plants (NW-VP) in an ombrotrophic peatland in northeastern Poland affected by moderate N deposition. We measured AG-NPP and elemental stoichiometry (C, N, P, Ca, Fe) in different plant species belonging to these functional plant groups, and growing within different microhabitats: Sphagnum bog hummocks and hollows, and Sphagnum mat. The functional groups significantly differed only in AG-NPP, but not in nutrient contents within the study sites. Sphagnum mosses had the highest mean production (247.6 g/m 2 ), while it was lower in NW-VP (71.7 g/m 2 ) and shrubs (49.4 g/m 2 ). The plant groups had a comparable N:P ratio. The N:P ratio was correlated with K, Ca, and Fe, but not with N in Sphagnum mosses. In NW-VP and shrubs, we observed an increased N:P ratio with increasing plant N content. However, increased N:P ratio was only negatively correlated with C content in Sphagnum mosses. Based on these data, we performed an analysis of elemental and production relations in peatland vegetation at the ecosystem level. Structural equation modelling (SEM) suggests that an increase of the N:P ratio in the vegetation, induced by higher N concentration, plus indirect effects of Fe, might explain a lower carbon concentration in plant production. As an outcome of this network of interactions, the AG-NPP of the entire peatland vegetation might be reduced. [ABSTRACT FROM AUTHOR]

Understanding the interactions between mineral nutrition and disease is essential for crop management. Our previous studies with Arabidopsis thaliana demonstrated that potassium (K) deprivation induced the biosynthesis of jasmonate (JA) and increased the plant's resistance to herbivorous insects. Here we addressed the question how tissue K affects the development of fungal pathogens and whether sensitivity of the pathogens to JA could play a role for the K-disease relationship in barley (Hordeum vulgare cv. Optic). We report that Kdeprived barley plants showed increased leaf concentrations of JA and other oxylipins. Furthermore, a natural tip-to base K-concentrations gradient within leaves of K-sufficient plants was quantitatively mirrored by the transcript levels of JA-responsive genes. The local leaf tissue K concentrations affected the development of two economically important fungi in opposite ways, showing a positive correlation with powdery mildew (Blumeria graminis) and a negative correlation with leaf scald (Rhynchosporium commune) disease symptoms. B. graminis induced a JA-response in the plant and was sensitive to methyl-JA treatment while R. commune initiated no JA-response and was JA-insensitive. Our study challenges the view that high K generally improves plant health and suggests that JA-sensitivity of pathogens could be an important factor determining the exact K-disease relationship. [ABSTRACT FROM AUTHOR]

Abstract: Balanced applications of nitrogen (N), phosphorus (P), and potassium (K) are known to increase grain yield of wheat but the impact of the interactions among N, P, and K on root growth and nitrogen use efficiency (NUE) have not been proven. The aim of this study was to investigate the effect of balanced applications of N, P, and K on the rooting patterns and NUE of wheat. Two glasshouse experiments were conducted. A rhizobox study was used to assess the impact of interactions among N, P, and K fertilisers on total root length, biomass, specific root length, root length density, N use efficiency (NUE), and N uptake efficiency of the shoots (NUpEshoot) and N nutrition index. In a separate pot study, plants were grown to maturity to confirm the effect of the observed changes in root growth on NUE, NUpEgrain, and grain/biomass yield. In the rhizobox experiment when plants were supplied with N+P+K, total root biomass increased approximately six‐fold relative to plants grown with N alone or with no fertiliser. Plants exposed to N+P+K had NUpEshoot and NUE values that were five and ten times higher, respectively, than plants that received just fertiliser N. Plants supplied with N+P or N+P+K had N nutrition indices close to one (N‐adequate), while plants that only received N had an index of 0.62 (N‐deficient). The pot study confirmed that the changes in root length and biomass in plants exposed to N+P+K resulted in significant increases in NUE, NUpEgrain, shoot biomass, and grain yield at maturity. Interactions among fertiliser N, P, and K played a critical role in influencing root biomass and length, which was associated with increases in NUE, NUpEshoot and NUpEgrain. [ABSTRACT FROM AUTHOR]

Potassium (K + ) is a vital ion for many processes in the plant and fine-tuned ion channels control the K + -fluxes across the plasma membrane. GORK is an outward-rectifying K + -channel with important functions in stomatal closure and in root K + -homeostasis. In this study, post-translational modification of the Arabidopsis GORK ion channel and its regulation by 14-3-3 proteins was investigated. To investigate the possible interaction between GORK and 14-3-3s an in vivo pull-down from an Arabidopsis protein extract with recombinant GORK C-terminus (GORK-C) indeed identified endogenous 14-3-3s (LAMBDA, CHI, NU) as binding partners in a phosphorylation dependent manner. However, a direct interaction between 14-3-3's and GORK-C could not be demonstrated. Since the pull-down of 14-3-3s was phosphorylation dependent, we determined GORK-C as substrate for CPK21 phosphorylation and identified three CPK21 phospho-sites in the GORK protein (T 344 , S 518 and S 649 ). Moreover, interaction of 14-3-3 to CPK21 strongly stimulates its kinase activity; an effect that can result in increased GORK phosphorylation and change in activity. Using the non-invasive vibrating probe technique, we measured the predominantly GORK mediated salt induced K + -efflux from wild-type, gork , cpk21 , aha2 and 14-3-3 mutant roots. The mutants cpk21 and aha2 did not show statistical significant differences compared to WT. However, two (out of six) 14-3-3 isoforms, CHI and PHI, have a clear function in the salt induced K + -efflux. In conclusion, our results show that GORK can be phosphorylated by CPK21 and suggest that 14-3-3 proteins control GORK activity through binding with and activation of CPK21. [ABSTRACT FROM AUTHOR]

The current work was aimed to elucidate the role of engineered nanosilica (SiNPs) particles to mitigate the damaging impacts of Na + -derived salinity on cucumber ( Cucumis sativus ) Beit Alpha variety by conducting in vitro experiments applying various Na + concentrations i.e. 0, 1000, 2000, 3000, 4000 and 5000 mg L −1 . By treating seeds and seedlings, respectively, of cucumber with SiNPs (0, 100, 200 and 300 ppm) and subsequent determination some germination and vegetative parameters as well as chemical analysis of seedlings, we verified that SiNPs succeeded to alleviate the detrimental effects of high Na + salinity by increasing germination parameters and vegetative growth of cucumber seedlings. Even as little as 100 ppm of N-Si results in considerable improvement of seed germination and seedlings growth of cucumber compared to the control, while 200 ppm was optimal among the doses tested. At 5000 mg Na + L −1 , applying SiNPs with 200 ppm increased final germination percentage by 101% over control, vigor index by 101%, germination rate index by 116%, germination index by 110%, fresh mass by 13%, K + /Na + ratio by 77%, shoot dry mass by 384%, root dry mass by 304% and plant height by 70%. The results mentioned in this paper obviously outline the large practical relevance of SiNPs and imply that applying of SiNPs for cucumber seeds and seedlings under high Na + -derived salinity enhances germination and growth as a result for decreasing Na + uptake and sequentially improves high K + /Na + ratio. [ABSTRACT FROM AUTHOR]

Pitaya is a fruit that is becoming promising for cultivation around the world due to the quality of its fruits in terms of taste and their peculiar external shape. Because it is a recenttly cultivated crop, information about fertilization is essential to enable its production. In this sense, this study was performed aiming to evaluate different doses of K2O for pitaya cultivation. Hylocereus undatus and Hylocereus polyrhizus were studied under field conditions. Pitayas were cultivated at a 3 x 3m spacing, and four doses of K2O were tested: 0, 50, 100, and 200 g plant-1, with a 2 x 4 factorial arrangement distributed in a randomized block design. The production per plant (kg and number of fruits) was evaluated in the production cycles of 2013/2014, 2014/2015, and 2015/2016. The fruit quality was also evaluated: longitudinal diameter, transverse diameter, mass, soluble solids content, titratable acidity and soluble solids/titratable acidity ratio. Potassium fertilization increased production and provided a better quality of pitaya fruits.K2O fertilization should be from 106.0 to 133.3 g K2O in the first year and 200 g K2O in the second and third years after planting. [ABSTRACT FROM AUTHOR]

We investigated how plant height, number of stem and branch, seed production and seed germination ofCapsella bursa-pastoriswere affected by nitrogen (N), phosphorus (P) and potassium (K) fertilizer using a pot fertilizer experiment. Plant growth parameter was determined, and fully ripen seeds were tested for germination.C. bursa-pastorisexhibited great phenotypic variation in plant height, number of stem and branch in relation to N, P and K supply. Seed production per plant was lowest in the control and low P treatment, and highest in NPK treatment. More than 16,000 seeds per plant were produced in treatments where N and P were applied together. A balanced N, P and K supply results in producing a high percentage and fast germinating seeds, while a deficiency of P and K together with a high N supply results in low germination ability and fast germinating of the produced seeds inC. bursa-pastoris. [ABSTRACT FROM PUBLISHER]

A laboratory experiment was conducted during 2015 and 2016 seasons to improve uptake and productivity of grapevines by producing three newly strains of solubilizing K bacteria (Histidineless, Argnineless and Phenylalanineless) by exposing the wild Streptomyces sp. with different doses of Ultraviolet irradiation from one to five minutes. These newly K strains as well as the slow release K fertilizer feldspar was used as a partial replacement of mineral K namely potassium sulphate (48% K2O). Supplying the vines with K as 50 to 75% mineral K plus feldspar as a slow release K fertilizer at 25 to 50% and any one of the three K bacterial strain each at 5 to 10 ml had an announced promotion on growth characteristics, pigments, N, P, K, Mg, Ca and S, berry setting (%), yield as well as physical and chemical characteristics of the berries relative to the application of K as mineral K alone. The best K strain was Histidineless followed by Phenylalanineless and strain Argnineless occupied the last position. The berries quality was remarkably enhanced due to supplying the vines with K as 50% mineral K + feldspar at 50% + Argnineless strain at 10 ml/vine. For promoting yield of superior grapevines, it is advised to supply the vines with K as 50% inorganic K plus 50% feldspar and Histidineless strain at 10 ml/vine. Supplying the vines with K as 25% mineral K + 75% feldspar + 20 ml (Argnineless strain) gave the best results with regard to berries quality. [ABSTRACT FROM AUTHOR]

Drought impedes the acquisition of potassium (K) by restricting root growth, in turn causing a reduction in the plant's K nutritional status, thereby further depressing its tolerance of the stress. The product of RAA1 ( Root Architecture Associated 1 ) is involved in the auxin-mediated development of the rice root system. Here, the introduction of a transgene comprising RAA1 driven by the promoter of HAK1 , a gene which encodes a drought-enhanced K transporter, was shown to exert a positive effect on the size of the root system and the number of adventitious roots formed. Transgenic seedlings demonstrated a higher level of tolerance to moisture stress than wild type (WT) ones, accumulated more K, proline and abscisic acid and suffered a lower level of lipid peroxidation. The genes AKT1 , HAK1 and HAK5 were all up-regulated in the roots of transgenic drought-stressed hydroponics-grown seedlings, as were several known stress-responsive genes in the leaves of soil-grown, moisture-stressed transgenic plants. Under moisture deficient conditions, the transgenic plants developed more effective tillers than did WT plants, showed an enhanced level of spikelet fertility and produced larger grains. While under moisture sufficient conditions there was no significant difference in the grain yield of the transgenic and WT lines, under water limiting conditions, the transgenics recorded a 20–40% grain yield advantage over the WT. The implication was that the promotion of root growth and development achieved by enhancing the expression of RAA1 in the root could represent a viable approach for enhancing the productivity of cereal crops exposed to moisture stress. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of gypsum on the release rate of potassium (K) and iron (Fe) from phlogopite to alfalfa under greenhouse conditions. The medium was a mixture of quartz sand as filling material, K- and Fe-bearing micaceous mineral (phlogopite) and different levels of gypsum (0%, 2%, 5%, 12% and 25%). During the 6-month cultivation period, the pots were irrigated and/or fed with distilled water and four different nutrient solutions. The results showed statistically significant effects of different levels of gypsum on dry weight and K and Fe concentration of shoots and roots. It seems that an increase in calcium (Ca) concentration, due to the addition of gypsum, changes the equilibrium of K and Fe in the root zone and plant tissues. The results of this study show that the rate of K and Fe release from micaceous minerals is extremely reduced in the presence of gypsum. [ABSTRACT FROM PUBLISHER]

Plants have the ability to suppress microbial nitrification process through secondary metabolites released from their root exudates or/and leaf litter. For decades, grasses were suggested to control nitrification process, and recently,Brachiaria humidicolaaccession 26159 (BH) as a tropical and subtropical grass has been shown to reduce nitrification rates under laboratory and soil conditions. In this study, experiments were conducted under controlled conditions in nutrient solution culture to investigate whether the reported release of natural nitrification inhibitors from root exudates of BH is an active or passive phenomenon. So different variables such as N-form (nitrate vs. ammonium), collecting medium (distilled water vs. 1 mM NH4Cl) and collecting period (6 vs. 24 hrs) were included to study the hypothesis. Results showed when root exudates were collected in distilled water there was no nitrification inhibition activity for all ammonium and nitrate grown plants. However, when collection was done in a medium containing 1 mM NH4Cl, root exudates showed significant nitrification inhibition activity similar to results obtained by Subbarao et al. The observed nitrification inhibition activity had a positive correlation to ammonium treatment particularly in collection medium, probably due to root cells damage induced by low pH and membrane depolarization under ammonium nutrition. This was more supported by application of shoot homogenates of NH4+, NO3−or NH4NO3grown plants that showed significant nitrification inhibition activity compared to distilled water and DMPP controls in a bioassay test, independent of N-form. Potassium concentrations in root exudates (as a result of potassium leakage) were found to increase in root washings of plants, which were grown with ammonium, particularly when root exudates were collected in 1 mM NH4Cl solution. In addition, higher electric conductivity of root washings after collection of root exudates in ammonium containing medium (low pH) and also in nitrate containing medium which adjusted to pH 3 by applying H2SO4, strongly suggest that release of natural nitrification inhibitors from root exudates ofB. humidicolamay not be an active process, but instead it is rather a passive phenomenon by ammonium induced root physicochemical damages. [ABSTRACT FROM PUBLISHER]

Gladiolus corms were grown in media contaminated with cadmium (Cd) (50 mg kg−1) and supplemented with silicon (Si) and potassium (K). The role of Si and K for mitigation of Cd toxicity was evaluated. Cd-induced stress generated significantly increased level of oxidative stress markers including hydrogen peroxide (H2O2), and malondialdehyde (MDA) in gladiolus. The application of K and Si improved the production of protein and proline in the treated plants. Moreover, K and Si supplemented plants exhibited an improvement in the activity of antioxidant enzymes and a reduction in the level of MDA, H2O2and Cd uptake under Cd stress. Application of K and Si also enhanced the uptake of mineral nutrients including calcium (Ca), magnesium (Mg), manganese (Mn), sulfur (S) and K. The plants supplemented with K and Si exhibited a higher amount of total phenolics and flavonoids. The combined effect of Si and K was more pronounced regarding beneficial effects on gladiolus plants compared to individual effect of these elements under Cd stress. The current research reveals that Si and K may improve gladiolus growth by decreasing the oxidative stress and Cd uptake and by increasing the activity of antioxidant defense enzymes, the quantity of secondary metabolites and plant nutrition. [ABSTRACT FROM PUBLISHER]

Acquaintance of potassium (K) transformation in soil is crucial for K management in management system of arid India. Present study revealed that the extractable K like ammonium acetate–potassium (NH4OAc–K), nitric acid (HNO3)–K, and hydrochloric acid (HCl)–K under different systems were followed the order: irrigated low input > rainfed low input > irrigated high input > no input. The pearl millet systems in irrigated low input practice maintained a higher NH4OAc–K than irrigated high input practice. The exchangeable-K (Exch-K), non-exchangeable-K (Non-exch K) and lattice-K were observed highest in irrigated low input system and lowest in no input system. It is noticed that Exch-K contributed 2.3–2.6% over total-K, which readily available to plants. The Exch-K was highly significant correlated with K pools and soil properties, indicating that rapid establishment of equilibrium between the pools. Thus, knowing K reserve and distribution of K forms can help in understanding K replenishment capacity of arid soil under long-term intensive cultivation. [ABSTRACT FROM AUTHOR]

In strawberry, potassium fertilization has been little studied, which difficult management strategies for an increasing yield and understanding the use of this nutrient in strawberry crop. The aim of this study was to evaluate the influence of sources and rates of potassium (K) fertilizers on yield, K level and agronomic traits of strawberry cv. Camarosa fruit, carried out under greenhouse conditions. A randomized in a completely block design with four replicates in a factorial arranged 6x3 (six rates of potassium x three sources of potassium fertilizers), was performed. Fertilizers sources used were as follows: potassium sulphate, potassium nitrate and potassium chloride in 0, 60, 120, 180, 240 and 300 kg ha-1 K2O doses. An increasing potassium rates have allowed a higher potassium content in leaves and fruits. A higher potassium content in leaves was obtained by KNO3 (11.70 g kg- 1). Yield, fruit number per plant and potassium extraction per plant, increased linearly with the evaluated doses and fruit average weight at a dose of 183 kg ha-1. There was no significant difference among potassium content in leaves. Strawberry production is maximized through potassium fertilization, independent of the source origin. [ABSTRACT FROM AUTHOR]

One of the causes of overusing compound and simple fertilizers in "Oriente Antioqueño" region is the low offer of research articles on fertilization in broccoli. Two experiments were carried out at municipality of Rionegro, Antioquia (Colombia). The first experiment was conducted in the second semester of 2013 in which two broccolis cultivars, Compact and De Cicco, were used. A randomized complete block design (RCBD) with four nitrogen doses (0, 50, 90 and 130 kg N ha-1) was arranged in a factorial 2 x 4, getting eight treatments. Using "San Cristobal" model in a RCBD design, Avenger and Legacy cultivars were grown in the second semester of 2014 including four levels of N, P2O5 and K2O as factors, arranging a total of 12 treatments in an incomplete factorial. Results of this experiment showed that in the first test, Compact cultivar reached a maximum production of 15.5 t ha-1 and De Cicco developed non-tradable inflorescences where a dose of 90 kg N ha-1 was applied, showing a low adaptation to this environmental conditions. In the second experiment, the relative growth height rates -stem diameter and yields- did not show significant statistical differences (P>0.05) regarding the treatments and cultivars evaluated. Avenger and Legacy got the highest yields, 19.0 and 12.2 t N ha-1 respectively, using doses of 60 kg N ha-1, 40 kg P2O5 ha-1 and 55 kg K2O ha-1. [ABSTRACT FROM AUTHOR]

To assess the robustness of the apparent sugar-potassium relationship during ripening of grape berries, a controlled-environment study was conducted on Shiraz vines involving ambient and reduced (by 34%) atmospheric CO 2 concentrations, and standard and increased (by 67%) soil potassium applications from prior to the onset of ripening. The leaf net photoassimilation rate was decreased by 35% in the reduced CO 2 treatment. The reduction in CO 2 delayed the onset of ripening, but at harvest the sugar content of the berry pericarp was similar to that of plants grown in ambient conditions. The potassium content of the berry pericarp in the reduced CO 2 treatment was however higher than for the ambient CO 2 . Berry potassium, sugar and water content were strongly correlated, regardless of treatments, alluding to a ternary link during ripening. Root starch content was lower under reduced CO 2 conditions, and therefore likely acted as a source of carbohydrates during berry ripening. Root carbohydrate reserve replenishment could also have been moderated under reduced CO 2 at the expense of berry ripening. Given that root potassium concentration was less in the vines grown in the low CO 2 atmosphere, these results point toward whole-plant fine-tuning of carbohydrate and potassium partitioning aimed at optimising fruit ripening. [ABSTRACT FROM AUTHOR]

Abstracts Young olive ( Olea europaea L.) plants generated from seed were grown in liquid hydroponic medium exposing the roots system for 33 days or 24 h to high temperature (37 °C) while the aerial part to 25 °C aiming to determine the prolonged and immediate effects of root warming on K + (Rb + ) transport in the root and consequently on plant growth. The exposition of the root system to 37 °C for 24 h inhibited K + (Rb + ) transport from root to shoot having no effect on its uptake. However, when the root system was exposed permanently to 37 °C both the K + (Rb + ) uptake and translocation to the aerial part were inhibited as well as the growth in all plants organs. The ability of the root system to recover K + (Rb + ) uptake and transport capacity after being exposed to high temperature was also evaluated. Plants grown in a root medium at 37 °C for 31 days were transferred to another at 25 °C for 48 or 96 h. The recovery of K + (Rb + ) root transport capacity after high root temperature was slow. Any signal of recovery was observed after 48 h without stress: both potassium root uptake and subsequent transport to above organs were inhibited yet. Whereas 96 h without stress led to restore potassium upward transport capacity although the uptake was partially inhibited yet. The results obtained in this study have shown that the root system of young olive plants is very sensitive to high temperature related to root potassium transport and growth of the plant. Taking into account the two processes involved in root potassium transport, the discharge of K + to the xylem vessels was more affected than the uptake at the initial phase of high root temperature stress. However, it was the first process to be re-established during recovery. All this could explain the symptoms frequently observed in olive orchards when dry and high temperature spells occur: a reduction in shoots growth and leaves with low levels of potassium contents and dehydration symptoms. [ABSTRACT FROM AUTHOR]

The effect of soil exchangeable (plant-available) potassium (ExK) content on cesium (Cs) absorption and translocation in buckwheat was evaluated in a field contaminated with radioactive Cs (134Cs and137Cs, RCs) in 2013. The RCs concentration in buckwheat was significantly positively correlated with the naturally occurring stable Cs (133Cs, SCs) concentration, and was lower at higher soil ExK content. The RCs and SCs were actively absorbed by buckwheat until the flowering stage. The soil ExK content was significantly negatively correlated with soil exchangeable RCs and SCs (ExRCs and ExSCs) concentrations. Greater RCs and SCs absorption by buckwheat in soils with low ExK contents was mainly due to higher soil ExRCs and ExSCs concentrations. Reproductive organs showed the largest differences in SCs concentration between low-ExK and high-ExK plots. The root–shoot and shoot–reproductive organs translocations of SCs markedly decreased with increasing soil ExK content. In the root–shoot and shoot–reproductive organs translocations, the discrimination of SCs and K decreased with decreasing soil ExK content. Our main findings were as follows: (1) because RCs are mainly taken up at the earlier growth stage, potassium should be applied as a basal fertilizer to decrease the RCs concentration in buckwheat; (2) lower soil ExK content led to higher soil ExRCs concentrations, resulting in greater RCs absorption by buckwheat; (3) the high Cs absorption and translocation and weaker discrimination between Cs and K in low ExK content soil may be due to the expression of K transporter(s) with weak discrimination between Cs and K. [ABSTRACT FROM PUBLISHER]

Agrobacterium-mediated transformation is an important research tool for the genetic improvement of cassava. The induction of friable embryogenic callus (FEC) is considered as a key step in cassava transformation. In the present study, the media composition was optimized for enhancing the FEC induction, and the effect of the optimized medium on gene expression was evaluated. In relative comparison to MS medium, results demonstrated that using a medium with reducing nutrition (a 10-fold less concentration of nitrogen, potassium, and phosphate), the increased amount of vitamin B1 (10 mg/L) and the use of picrolam led to reprogram non-FEC to FEC. Gene expression analyses revealed that FEC on modified media increased the expression of genes related to the regulation of polysaccharide biosynthesis and breakdown of cell wall components in comparison to FEC on normal CIM media, whereas the gene expression associated with energy flux was not dramatically altered. It is hypothesized that we reprogram non-FEC to FEC under low nitrogen, potassium and phosphate and high vitamin B1. These findings were more effective in inducing FEC formation than the previous protocol. It might contribute to development of an efficient transformation strategy in cassava. [ABSTRACT FROM AUTHOR]

Intensive use of Brazilian pastures without the maintenance of soil fertility has decreased their productivity and favoring the onset of symptoms of nutritional deficiency. The objective of this study was to evaluate the effect of nitrogen, potassium, calcium and sulfur omission in symptomatology, growth and dry mass accumulation in grass Convert. The experiment was conducted in a greenhouse with a completely randomized design, with five treatments and four replications. The treatments were: full nutrient solution, nitrogen omission (N), potassium omission (K), calcium omission (-Ca) and sulfur omission (S). The variables were the number of tillers, leaf number, root size, shoot height, characterization of symptoms of deficiency and shoot and root dry mass accumulation. The data were submitted to the F test by analysis of variance and comparison of means by Tukey's test (p <0.05). The omission of N, K, Ca and S limited the development of Convert grass compared to the full nutrient solution treatment, reducing the number of leaves, tillers, height, root size and dry mass production. The nutrient omission modified forage morphology, showing visual symptoms of deficiency of each nutrient evaluated. The decreasing order of onset of symptoms was N, Ca, S and K. [ABSTRACT FROM AUTHOR]

It is predicted that atmospheric carbon dioxide (CO 2 ) level will double by the end of the current century. Although the fertilization effect of CO 2 on plant growth is well documented, studies that investigate plant nutritional requirements under elevated CO 2 are scarce. Potassium (K) is an essential plant nutrient with prominent roles in key physiological processes. Aim of this work, was to determine the effects of K deficiency on plant growth as affected by elevated CO 2 and how antioxidant defense systems (activities of SOD, CAT, POX, APX, GR, MDHAR, DHAR, lipid peroxidation and total antioxidant activity) respond to K deficiency under ambient (a-CO 2 : 400 ppm) or elevated (e-CO 2 : 900 ppm) atmospheric CO 2 conditions in durum ( Triticum durum cv. Sarıçanak-98) and bread wheat ( Triticum aestivum cv. Adana-99). Plants were grown in hydroponics with sufficient (1850 μM), low (60 μM) or deficient (20 μM) K and under a-CO 2 or e-CO 2 . As expected, e-CO 2 promoted biomass production with adequate K supply, however in low and deficient K plants biomass was either not affected or even decreased by e-CO 2 . It was observed that low or deficient supply of K induced oxidative stress, but e-CO 2 had no significant impact on antioxidative response of plants and thus could not alleviate detrimental effects of K deficiency. Under K deficiency, CAT activity decreased in both species but this decrease was accompanied with increases in POX and APX which may be for adapting to the changing environment. In general, responses in antioxidant defense enzymes were linked to K nutritional status of plants rather than e-CO 2 conditions. [ABSTRACT FROM AUTHOR]

The uptake of stable cesium ( 133 Cs) by Calla palustris was evaluated from four different substrates: water, soil, keramzit (a clay granule) and water with the addition of a potassium compound, after an eight days exposure to a solution of 0.5 mM cesium chloride. Stable cesium was used because it is commonly supposed that its uptake by plants is the same of that of radiocesium ( 137 Cs). The plants were differentiated in their parts (roots, healthy leaves, dead leaves and flowers) and analyzed with ICP-MS. The lowest average concentration of absorbed Cs was found in plants exposed in soil (0.7 mg/kg, S.D.=96.8), while the highest in plants exposed in water (147 mg/kg, S.D.=51.7). During the experiment the water planted plants removed 31.6% of provided Cs while those planted in soil removed only 0.06%. The addition of potassium to water was tested because of the competition effect that arises between these two elements: this effect was confirmed with the result that the average uptake in the presence of potassium was lower (41 mg/kg in exposed plants, S.D.=76.1). The uptake was also lower in the solid-based substrates (soil and keramzit), because of the known tendency of Cs to bind with soil particles, thus becoming less available to plants. There was no evidence that the different parts of the plant showed different uptake effectiveness, or that the health of the plant (evaluated with a qualitative method) had any effect on the uptake of Cs. [ABSTRACT FROM AUTHOR]

Tomato ( Solanum lycopersicum cv. ‘Moneymaker’) was transformed with the choline oxidase gene codA from Arthrobacter globiformis , which was modified to allow for targeting to both chloroplasts and the cytosol. Glycine betaine (GB) was accumulated in transformed plants, while no detectable GB was found in wild-type (WT) plants. Compared to WT plants, transgenic lines showed significantly higher photosynthetic rates (Pn) and antioxidant enzyme activities and lower reactive oxygen species (ROS) accumulation in the leaves when exposed to salt stress. Furthermore, compared with WT plants, K + efflux decreased and Na + efflux increased in roots of transgenic plants under salt stress; resulted in lower Na + /K + ratios in transgenic lines. The exogenous application of GB also significantly reduced NaCl-induced K + efflux and increased Na + efflux in WT plants. A qRT-PCR assay indicated that GB enhanced NaCl-induced expression of genes encoding the K + transporter, Na + /H + antiporter, and H + -ATPase. These results suggest that the enhanced salt tolerance conferred by codA in transgenic tomato plants might be due to the regulation of ion channel and transporters by GB, which would allow high potassium levels and low sodium levels to be maintained in transgenic plants under salt stress condition. [ABSTRACT FROM AUTHOR]

To assess the effects of ozone (O3) on uptake and utilization of nitrogen, phosphorus, and potassium nutrients in rice for planning rational fertilization under projected O3elevation. Two hybrid indica cultivars were exposed to ambient and elevated O3(E-O3) under a free-air O3enrichment system. E-O3differently affected the accumulation and distribution of biomass, and the absorption and distribution of nutrients between cultivars. These effects were related to rice cultivar and nutrient type. E-O3led to significantly decreased partial factor productivity and grain production efficiency (GPE) of nitrogen in both cultivars; however, the effects of E-O3on GPEs of phosphorus and potassium varied with cultivar. Responses of nutrients harvest indices between cultivars to E-O3were adverse. Differences between cultivars and elements should be considered when examining E-O3potentially affecting the nutrient dynamics for the purpose of reducing the amount of fertilizer applied in paddy systems to decrease potential environmental pollution. [ABSTRACT FROM PUBLISHER]

Saline soils are highly heterogeneous in time and space, and this is a critical factor influencing plant physiology and productivity. Temporal changes in soil salinity can alter plant responses to salinity, and pre-treating plants with low NaCl concentrations has been found to substantially increase salt tolerance in different species in a process called acclimation. However, it still remains unclear whether this process is common to all plants or is only expressed in certain genotypes. We addressed this question by assessing the physiological changes to 100 mM NaCl in two contrasting olive cultivars (the salt-sensitive Leccino and the salttolerant Frantoio), following a 1-month acclimation period with 5 or 25 mM NaCl. The acclimation improved salt tolerance in both cultivars, but activated substantially different physiological adjustments in the tolerant and the sensitive cultivars. In the tolerant Frantoio the acclimation with 5 mM NaCl was more effective in increasing plant salt tolerance, with a 47% increase in total plant dry mass compared with non-acclimated saline plants. This enhanced biomass accumulation was associated with a 50% increase in K+ retention ability in roots. On the other hand, in the sensitive Leccino, although the acclimation process did not improve performance in terms of plant growth, pre-treatment with 5 and 25 mM NaCl substantially decreased salt-induced leaf cell ultrastructural changes, with leaf cell relatively similar to those of control plants. Taken together these results suggest that in the tolerant cultivar the acclimation took place primarily in the root tissues, while in the sensitive they occurred mainly at the shoot level. [ABSTRACT FROM AUTHOR]

A rapid quantification method for leaf sodium (Na+) and potassium (K+) concentrations was developed using a compact ion meter. Leaf ion concentrations were evaluated for species ofVigna vexillata(L.) A. Rich. after two weeks of treatment with 0–200 mM of sodium chloride. To compare the ion extraction efficiency, extraction solutions of distilled water and ammonium acetate were tested. The ion concentrations of extracts obtained by both solutions were measured using an ion meter, and the values were validated using ion chromatography. For both extraction solutions, the ion meter values were highly correlated with those of the ion chromatograph. However, correlations between ion meter and chromatograph values were largely different for Na+and K+. The rapid quantification of ion concentrations using an ion meter developed in this study was successfully utilized for evaluating differences in leaf Na+concentrations, K+concentrations, and K+/Na+ratio in species ofV. vexillata. [ABSTRACT FROM PUBLISHER]

A field experiment was conducted during 2014-15 season. Mineral potassium fertilizer of 0, 50, 75 and 100 kg/ha and boron at 0, 5, 10 and 15 kg/ha with a uniform dose of nitrogen and phosphorus at 80 and 50 kg/ha, respectively. The highest mean vegetative parameters (plant height, number of leaves per plant, fresh weight and dry weight of leaves) were from a treatment combination of 100 kg N and 15 kg Band yield and yield were maximum from a treatment combination of 75 kg N and 10 kg B. Application of potassium and boron at higher doses positively affected carrot root production. [ABSTRACT FROM AUTHOR]

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