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Nitrogen (N) derived from the decomposition of litter from cover crops can contribute to the mineral nutrition of citrus trees. This study aimed to assess the prior contribution of N derived from the decomposition of forage radish (Raphanus sativus) and black oats (Avena strigosa) to Satsuma mandarin tree N demand. Forage radish and black oats were grown and enriched with 15N stable isotope. Two studies were conducted on (1) non-bearing, potted satsuma mandarin seedlings for 120 days in the greenhouse (Experiment 1) and (2) bearing field-growing Satsuma mandarin trees for 270 days (Experiment 2). Tree growth and total N and 15N concentrations were determined in annual and perennial organs of citrus and soil. The highest value of N derived from the decomposition of cover crop root residues was observed in the leaves and roots of non-bearing trees, while the highest amount of N derived from shoot residue decomposition was observed in the leaves of bearing trees. The results showed little contribution of the decomposition of residues of forage radish and black oats on the total N budget of annual and perennial organs of both bearing and non-bearing Satsuma mandarin trees, probably because the climatic conditions promoted a fast N mineralization and possible losses through volatilization and leaching. [ABSTRACT FROM AUTHOR]

Fruit crops under soil conservational management might sequester carbon (C) in soils and mitigate greenhouse gases emissions. Using grape pomace residues as soil amendment holds promise for sustainable viticulture. However, its actual capability to increase soil organic carbon (SOC) and nitrogen (N) is unknown, especially in subtropical climates. This research aims to investigate whether grape pomace compost and vermicompost can increase SOC, total N (TN), and C and N stocks in subtropical vineyards. Two vineyards located in Veranópolis, in South Brazil, one cultivated with 'Isabella' and the other with 'Chardonnay' varieties, were annually amended with these residues for three years. We quantified SOC and TN in each condition in different soil layers, as well as C and N content in two different granulometric fractions: mineral-associated organic matter (MAOM) and particulate organic matter (POM). C and N stocks were also calculated. Despite potential benefits, neither treatment enhanced SOC, its fractions, or C stocks. In fact, vermicompost was rapidly mineralized and depleted SOC and its fractions in the 0.0 to 0.05 m layers of the 'Isabella' vineyard. Our findings indicate that the tested grape pomace residues were unable to promote C sequestration in subtropical vineyards after a three-year period. [ABSTRACT FROM AUTHOR]

Environmental extremes, such as drought and flooding, are becoming increasingly common, resulting in significant crop losses. The aim of the present study was to understand the molecular response induced by drought and waterlogging conditions, and to link these responses to the physiological adaptation of plants. For this purpose, leaf RNA expression was analyzed in potted kiwifruit plants by Illumina Next Generation Sequences. Stressed plants showed an impairment of all physiological parameters (leaf-gas exchange and stem-water potential) with a more evident effect in waterlogging condition than in drought condition. However, the impact on the transcriptome in waterlogged plants was less intense than in drought stress. Drought affected several metabolic pathways, among which "plant hormone signal transduction", "protein processing in endoplasmic reticulum", and "mitogen-activated protein kinase signaling pathway" were the most representative in terms of number of genes involved. The genes involved in the biosynthesis of phenylpropanoids were positively influenced by both drought and waterlogging. Finally, waterlogging stimulated secondary metabolisms by upregulating the genes responsible for the biosynthesis of terpenoids and flavonoids, such as stilbenoids. The obtained results show that the two contrasting stress conditions share several common physiological responses and molecular mechanisms. [ABSTRACT FROM AUTHOR]

The current political, social, and economic conditions place, more than ever, the need to sustainably supply nutrients for plants, integrating low-impact, crop-adapted, variable-rate-application fertilizer solutions, at the center of attention. Fertilization plans should be based on the monitoring of soil fertility to address the proper rate of fertilizer application along with the development of techniques able to increase nutrient uptake efficiency. Monitoring and modelling analysis of the effects of agronomic management in different pedoclimatic conditions can provide several advantages, that include higher nutrient efficiency, increase in plant growth and yield, decreased fertilization costs, increased profit, reduced environmental impact. This approach should enter into a framework of precision farming methodologies for the distribution of nutrients adopted at different levels (region, farm, field, plot), to obtain the maximum efficiency of inputs. [ABSTRACT FROM AUTHOR]

Persimmon is a typical fruit crop of the Mediterranean region and, since it is considered a minor species, little information is available on its nutrients need. In the present experiment, it was estimated the quantity of removed and recycled nutrients by Kaki Tipo and Rojo Brillante, the two main varieties of persimmon grown in Emilia-Romagna region (Po Valley, Italy). Plants from ten mature orchards were selected and harvested; organs (leaves in summer, fruits at harvest, abscissed leaves, roots and skeleton) biomass and mineral composition were determined. The yearly uptake of macronutrients was similar for the 2 varieties, accounting for (kg ha−1): N 89-91, P 10-11, K 79-91, Ca 132-162, Mg 22-26 and S 9. While K was mostly found in fruits, Ca and Mg were mainly partitioned to leaves. Among micronutrients, Mn and Fe showed the highest values (1.1–1.3 and 1.2–2.1 kg ha−1, respectively), followed by B (370 g ha−1), while Cu and Zn showed the smallest amounts (less 100 g ha−1). Nitrogen, Ca, Mg and S were those more recycled than removed, while K showed an opposite trend; among the microelements, the annual recycled fractions of B and Mn were higher than that removed. [ABSTRACT FROM AUTHOR]

The intensification of highly specialized viticulture has led to a dramatic decrease of soil fertility that can be restored by increasing soil organic matter using organic fertilizers. The aim of the present experiment was to evaluate the effect of different organic amendments on vine vegetative growth and nutritional status, soil N availability and microbial biomass, as well as on yield and grape quality. The experiment was carried out in 2020 and 2021, on cv. Sangiovese (Vitis vinifera L.) vines grafted on 110 Richter (V. berlandieri × V. rupestris) planted in February 2019. Plants were fertilized yearly in spring with (1) mineral fertilization (MIN), (2) municipal organic waste compost (MOW), and (3) sewage sludge compost (SS). The application of SS increased nitrate availability in both years, while the supply of organic matter (no matter the source) enhanced soil microbial biomass content. Plant nutritional status was in the optimal range for all treatments, with an increase of N in SS and K in MOW. Fruit yield in 2020 was not influenced by treatments, while in 2021 it was enhanced by MIN and MOW, which also induced a higher berry quality. Plant vegetative growth was stimulated by the application of SS. In conclusion, from these preliminary results we observed a higher N availability as a consequence of SS supply that resulted in a higher plant biomass, but reduced yield and berry quality, supporting the theory that for vineyards, N should be carefully managed to reach an equilibrium between vegetative and reproductive activity. [ABSTRACT FROM AUTHOR]

Soil analysis is used to estimate nutrient availability, but nutrient concentrations are not always related to yield in most fruit plants, including grapevines. Thus, additional multivariate mathematical models, such as the compositional nutrient diagnosis (CND), which takes into account leaves nutrient concentration, and yield, can contribute to estimating critical levels or sufficiency bands of elements, as well as to detect deficiency and/or excess of nutrients. The aim of the present study was to establish CND standards, and the critical level and sufficiency band of nutrients, in the grapevine Vitis vinifera L., grown in a subtropical climate region. Leaves were collected in 81 vineyards in the Campanha Gaúcha do Rio Grande do Sul region, Southern Brazil, and analyzed for macroand micro-nutrient concentration. The yield of each vineyard was assessed. Grapevine nutritional status was calculated through the CND method. CND-r² indices were effective in establishing the nutritional status of grapevines for macro- and micro-nutrients as sub-optimal, excessive, or balanced. The CND methodology established the critical level and sufficiency bands of nutrients more accurately than the current recommendations for grapevines. Multi-nutrient associations were more effective than the single nutrient determination in defining the threshold of a given nutrient that can reduce grapevine yield. [ABSTRACT FROM AUTHOR]

The aim of the present experiment was to evaluate the effectiveness of soil electrical conductivity (EC) measurement as a fast tool to assess mineral nitrogen (N) in orchards, in order to define precise N inputs that can help farmers to reduce useless fertilizer application. During one vegetative season, seven orchards of different species, supplied with mineral or organic fertilization, were monitored. Nitrate soil concentration was measured monthly by laboratory analyses, while soil EC and moisture were recorded continuously by soil probes. Nitrate and EC were positively correlated, laying the foundation for the identification of a fast and reliable index. However, while some dates showed a high Pearson correlation coefficient, no correlation was found for others. The correlation was not affected by type of fertilizer, and was higher in silty-clay-loam than in loam soils. Pooling all of the data, a significant correlation with a Pearson coefficient of 0.75 was found. The soil optimal nitrate N availability was defined by an EC in the range of 0.3 to 0.6 mS cm-1. Although these are only preliminary results, our data are promising, showing a good suitability of soil EC measurement as a means to monitor soil mineral N availability. [ABSTRACT FROM AUTHOR]

Soil-Plant Interaction: Effects on Plant Growth and Soil Biodiversity The authors demonstrated that fallow fields have higher soil enzyme activity than soil after rice cultivation. Soil health and productivity are deeply influenced by several exchanges between plant, soil and microbes. [Extracted from the article]

Agricultural land abandonment is an emerging problem in European Union (EU), and about 11% of agricultural EU land is at high risk of abandonment in the coming 10 years. Land abandonment may have both positive and negative effects in ecosystems. Due to the potential for land abandonment to increase soil fertility, the study of vegetation succession effects on soil quality is of great importance. In this study, we investigated an abandoned vineyard where, after a period of 30 years, rows and alleys were characterized by two different forms of vegetation succession: natural recolonization by trees along the rows and by herbaceous vegetation in the alleys. No-tilled alleys covered by herbaceous vegetation of a neighboring conventionally cultivated vineyard were used as a comparison. Soil samples were chemically characterized (pH, extractable element, and available and total metals), and analyzed for the determination of carbon (C) and nitrogen (N) pools; hydrolytic and phenol oxidizing (PO) enzyme activities involved in C, N, and phosphorus (P) cycles; and the enzyme ratios. Results highlighted that natural recolonization by trees increased the organic C and N soil pools by 58% and 34%, respectively, compared to the natural recolonization by herbaceous vegetation. Moreover, natural recolonization by trees reduced β-glucosidase by 79%, urease by 100%, alkaline phosphastase by 98%, acid phosphatase specific hydrolytic activities by 50%, and catechol oxidase and laccase specific oxidative activities by 127% and 119%, respectively, compared to the renaturalization by herbaceous vegetation. In addition, the natural recolonization by trees reduced the C (βglu):C (PO) enzymes ratio by 16% compared to that of the conventional vineyard. Comparing the natural recolonization by herbaceous vegetation with that of the conventional vineyard revealed little significant difference (15% of the measured and calculated parameters); in particular, PO activities significantly decreased in the renaturalized vineyard with herbaceous vegetation by 49% (catechol oxidase) and 52% (laccase), and the C (βglu):C (PO) enzyme ratio showed a reduction (−11%) in the vineyard naturally recolonized by herbaceous vegetation compared to the conventional vineyard. This highlights that the type of vegetation succession that takes place after land abandonment may have a significant impact in terms of soil fertility and C accrual potential. These results help to focus attention on the practices used in agro-forestry that should be adopted in abandoned agro-ecosystems to increase their biodiversity, soil C stock, and soil quality, because these indicators are affected by the type of vegetative coverage. [ABSTRACT FROM AUTHOR]

Phosphorus (P) availability in subtropical soils does not often meet the nutritional demand of native tree species such as the ipê-roxo tree (Handroanthus heptaphyllus); therefore, it is necessary to supply P at planting. However, the impact of P on root system growth remains unknown. The aim of the current study was to investigate the effect of P application on root morphology of H. heptaphyllus plants over a 36-month period in a subtropical climate region. During the experiment, the plants subjected to fertilization with 40 kg P ha−1 were compared to untreated control. Plant roots were scanned through minirhizotron system 18 and 36 months after transplant (MAT), and generated images were used to determine total root length, mean root diameter and total root volume. Plant height and leaf P concentrations were also evaluated. Phosphorus application enhanced root and whole plant growth with a more evident effect at 36 MAT, when soil P availability decreased. The results give important information on the cultivation of H. heptaphyllus plants in soils presenting low P availability. [ABSTRACT FROM AUTHOR]

The aim of the present experiment was to determine if the supply of biofertilizers could differently stimulate the native microbiota, thus determining different patterns of organic material decomposition processes. The microbial composition of soil and litter was investigated by next generation sequencing using a metabarcoding approach. The chemical structure of the decomposing litterbags was investigated through the TG-DTA analysis and NIR spectroscopy. The study was conducted in an apricot orchard in Italy, and two different type of biofertilizers (AMF and Trichoderma spp.) were compared to unfertilized control over one year. Bacteria and fungi in soil, 162 days from litter deposition, evidenced differentiated clusters for control and both biofertilizers; on the other hand, only fungal composition of litterbags was modified as a consequence of Trichoderma spp. supply; no effect was observed in the bacterial community of litterbags. NIR and TG-DTA analysis evidenced a significant change over time of the chemical composition of litterbags with a faster degradation as a consequence of Trichoderma spp. supply testified by a higher degradation coefficient (1.9) than control (1.6) and AMF (1.7). The supply of biofertilizers partially modified the bacteria community of soil, while Trichoderma spp. Influenced the fungal community of the litter. Moreover, Trichoderma spp. Evidenced a faster and higher degradation of litter than AMF-biofertilizers, laying the foundation for an efficient use in orchard. [ABSTRACT FROM AUTHOR]