Adubação foliar (S, Mn e Zn) em diferentes estádios fenológicos do feijoeiro comum irrigado

O feijoeiro é uma planta exigente em nutrientes devido ao seu sistema radicular superficial e ciclo curto. A deficiência de manganês e zinco, pode reduzir a atividade metabólica devido à demanda em processos fisiológicos. O enxofre pode limitar a produtividade da cultura. Objetivou-se avaliar o desempenho do feijoeiro comum sob diferentes doses de fertilizante foliar aplicado em dois estádios fenológicos. O delineamento utilizado foi o DBC com quatro repetições e os tratamentos foram 5 doses de adubo foliar (0; 0,250; 0,500; 0,750; e 1 L ha-1) em dois estádios fenológicos de aplicação (V4 e R5). Como fonte de Mn, Zn e S foi usado o fertilizante foliar GRAIN SET®. Após 102 dias da semeadura foi realizado a colheita de forma manual, e os grãos secos ao ar a 13% de umidade. As variáveis analisadas foram: altura de planta (m), número de vagem por planta, número de grãos por vagem, massa de 1000 grãos (g) e produtividade (kg ha-1). Em relação ao estádio fenológico V4 e R5, somente a variável número de vagens por planta obteve diferença significativa. Para massa de mil grãos e produtividade houve efeito significativo. A produtividade ficou entre 3437,59 e 5543,58 kg ha-1. Esse aumento na produtividade se explica devido a presença de zinco no adubo foliar. A dose de 0,5 L ha-1 para massa de mil grãos obteve melhor desempenho de peso (285,40g).

Combined Foliar and Soil Selenium Fertilizer Improves Selenium Transport in Oats and the Diversity of the Bacterial Community in Rhizosphere Soil

Reasonable application of selenium (Se) fertilizer is beneficial for improving Se contents in grains and can affect soil ecology. No study has compared Se fertilizer application methods on biofortification, yield, and soil bacterial community. This study investigated the effects of topsoil (T), foliar (S), and soil+foliar (TS) application of Se fertilizer on oats. TS treatment significantly increased oat yield compared with the control and S. The Se content in grains was increased in the order of TS > S > T. T and TS increased the nutrients, soil organic matter, activities of urease, alkaline phosphatase, and sucrose, as well as the diversity and abundance of soil bacterial communities. According to PCA analysis, TS and T increased the relative abundance of bacteria involved in the decomposition of organic matter, such as Proteobacteria, Chloroflexi, and Bacteroidetes, while reduced Granulicella, Bacillus, Raoultella, Lactococcus, Klebsiella, and Pseudomonas. Furthermore, TS significantly increased the relative abundance of Aciditeromonas, Gemmatimonas, Geobacter, and Thiobacter. While, T significantly increased the abundance of Lysobacter, Holophaga, Candidatus-Koribacter, Povalibacter, and Pyrinomonas. S did not significantly change the bacterial communities. The redundancy analysis revealed that soil nutrients and enzyme activities were positively correlated with the abundance of Actinobacteria, Acidobacteria, Gemmatimonadetes, Bacteroidetes, Planctomycetes, and Chloroflexi, but negatively correlated with the abundance of Proteobacteria and Firmicutes. Thus, a combined application of foliar and soil Se proved most conducive for achieving higher yield, grain Se content, and improving bacterial community structure and functional gene expression in rhizosphere soil.

Synergistic Effect of Sulfur and Nitrogen in the Organic and Mineral Fertilization of Durum Wheat: Grain Yield and Quality Traits in the Mediterranean Environment

In recent years, awareness on sustainable land use has increased. Optimizing the practice of nitrogen fertilization has become crucially imperative in cropping management as a result of this current trend. The effort to improve the availability of organic nitrogen has incurred a bottleneck while seeking to achieve a high yield and quality performance for organic winter cereals. Field experiments were conducted, under rainfed Mediterranean conditions, over a period of two subsequent growing seasons. The objective was to investigate the effect of soil and foliar S application on the performance of three durum wheat cultivars fertilized with either organic or inorganic N. The hypothesis to be verified was if different S fertilization strategies could improve grain yield and quality when coupled with mineral or organic N fertilizer. There were three levels of treatment with mineral N fertilizer (120, 160 and 200 kg ha−1), two levels of organic N fertilizer (160 and 200 kg ha−1), two levels of S fertilizer applied to the soil (0 and 70 kg ha−1), and two levels of foliar S application at flag leaf stage (0 and 5 kg ha−1). Cultivars were Dylan, Iride and Saragolla. Analyzed traits were grain yield, yield components and quality features of grain. Overall, at the same N rate, grain yield and quality were markedly higher for mineral than organic N source. Cultivar × Year × N treatment interactions significantly affected grain yield and quality indices. Iride showed a high yield stability throughout the mineral N rates in the most favorable year (2011) and, in the same year, was the top performing cultivar in organic N treatments. Dylan was the top performing cultivar for protein content, while Saragolla for the SDS sedimentation test. Soil S fertilization had no effect on grain quality, whereas it significantly increased grain yield (+ 300 kg ha−1) when coupled with organic rather than a mineral N source. However, foliar S application at flag leaf stage did not affect grain yield, but it significantly enhanced quality indices such as test weight (81 vs. 79.9 kg hL−1), protein content (13.7% vs. 12.9 %) and SDS value (72.5 vs. 70.5 mm). A rate of 160 kg ha−1 of N (both mineral and organic) determined the optimal response for both grain yield and quality. Finally, soil and foliar application of S may help to contain the large yield and quality gap that still exists between mineral and organic fertilization of durum wheat.

Effects of Foliar Sulfur Sprays on Pecan Independent of Pecan Scab Control

Many commercial pecan [Carya illinoinensis (Wangenh.) K. Koch] producers routinely spray foliar urea and sulfur (S) in combination with their fungicide sprays, despite very little information available in the scientific literature regarding the effects of these practices on pecan production. The objectives of this study were to investigate the effects of foliar application of elemental S and urea, alone and in combination, on pecan leaf tissue nitrogen (N) and S concentration, pecan nut quality, leaf chlorophyll index (LCI), and pecan scab control. Foliar S sprays increased pecan nut weight over the control in 2 of 3 years of study. Pecan nut weight was unaffected by foliar urea sprays compared with the control, but nut weight was lower for foliar urea sprays compared with foliar S sprays in the first 2 years of study. Neither foliar S nor urea sprays affected pecan scab incidence or severity. Foliar S sprays failed to increase leaf S concentration throughout the study. Pecan leaf N and leaf S concentrations were lower in the foliar urea treatment than in the control and foliar S treatments during the initial year of study; however, no treatment differences were observed for urea after Year 1. Foliar S application enhanced LCI in 2011 and 2012. Leaf chlorophyll index was also increased by the combination of foliar urea and S in 2012. These results suggest that foliar S sprays may provide pecan producers with a tool with which to maximize nut size and increase the profitability of their crop.

Effects of different sources and rates of sulphur on the growth and foliar nutrition of nitrogen-fertilized lodgepole pine

The effects of nitrogen (N) fertilizer, alone and in combination with different sources and rates of sulphur (S), on foliar nutrients and tree growth are reported over 3 and 6 years, respectively. After 3 years, foliar S levels in the N+S treatments were significantly higher than those in N-only treatments at all six study locations. Temporal patterns of foliar S response varied significantly with S source. When applied as ammonium sulphate (AS), foliar levels increased sharply in year 1 and slowly declined over the next 2 years. Conversely, additions of elemental S (S0), in the form of S0 – sodium bentonite fertilizer, usually did not increase foliar S concentration in year 1, but had increasingly positive effects on foliar S in years 2 and 3. An increase in the S application rate from 50 to 100 kg/ha resulted in only a modest improvement in foliar S concentration for both S sources. Differences in individual-tree basal area increment between N and N+S treatments were statistically significant in only two of six trials. Prefertilization levels of foliar N and sulphate S, and probable induced deficiencies of nonadded nutrients following N fertilization, largely explained basal area and height responses to N and N+S additions at the six study sites. Despite delayed oxidation, S0 was as effective as the more readily available AS in stimulating radial growth after 6 years. However, the relative effectiveness of S source varied with S application rate in two trials. In both cases, basal area increment was positively related to application rate when S was applied as AS. Conversely, the effect of application rate was distinctly negative when S0 was applied. Despite large differences in short-term availability of AS and S0, the results from this study support the conclusion that the two S sources are likely equally effective in alleviating S deficiencies and in promoting tree growth of S-deficient lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.).

Foliar sulfur and nitrogen along an 800-km pollution gradient

Emissions of sulfur (S) and nitrogen (N) oxides in the midwestern and northeastern United States result in pronounced regional gradients of acidic deposition. The objective of this study was to determine the extent to which atmospheric deposition alters the uptake and cycling of S and N in five analogous northern hardwood forests located along one of the most pronounced regional gradients of SO42−-S and NO3−-N deposition in the United States. We tested the hypothesis that acidic deposition would alter foliar S and N ratios and nutrient cycling in aboveground litter fall. Sulfate in both wet deposition and throughfall increased by a factor of two across the 800-km deposition gradient. The July concentration of S in sugar maple (Acersaccharum Marsh.) leaves increased from about 1600 μg•g−1 at the northern research sites to 1800–1900 μg•g−1 at the southern sites. Differences in leaf litter S concentration were even more pronounced (872–1356 μg•g−1), and a clear geographic trend was always apparent in litter S concentration. The 3-year average S content of leaf litter was 63% greater at the southern end of the pollution gradient. Nitrate and total N deposition were also significantly greater at the southern end of the gradient. The concentration of N in both summer foliage and leaf litter was not correlated with N deposition, but the content of N in leaf litter was significantly correlated with N deposition. The molar ratios of S:N in mid-July foliage and leaf litter increased as atmospheric deposition of SO42−-S increased. Ratios of S:N were always much greater in leaf litter than in mid-July foliage. The molar ratios of S:N retranslocated from the canopies of these northern hardwood forests were less than those in mid-July foliage or litter fall and showed no geographic trend related to deposition, suggesting that S and N are retranslocated in a relatively fixed proportion. Significant correlations between SO42−-S deposition and foliar S concentration, S cycling, and the molar ratio of S:N in foliage suggest that sulfate deposition has altered the uptake and cycling of S in northern hardwood forests of the Great Lakes region.