Effect of fertilizer-N application and seed coating with rhizobial inoculants on soybean yield in eastern Paraguay

Nitrogen removal in soybean grains at harvest may exceed biological N2 fixation, particularly if grain yields are as high as typically achieved on "Terra Rossa" soils of Eastern Paraguay. Applying N fertilizer or coating seeds with rhizobial inoculants that enhance nodulation may represent a way of balancing the N budget. However, the effects of such treatments appear to be highly site-specific. The objective of this study was to examine the effects of N application (N) and rhizobial inoculation (I) on nodulation, N accumulation and soybean yields in Eastern Paraguay. Field experiments were conducted in two consecutive soybean seasons. Dry conditions in the first year delayed sowing and reduced plant number m-2 and pod number plant-1. Grain yields were generally below 2 t ha-1 but the +N+I treatment increased yields by about 75%. In the second year favorable conditions resulted in yields of around 4 t ha-1 and the treatments had no effect. Nitrogen accumulation was higher in the first year and could therefore not explain the observed yield differences between years and treatment combinations. The positive effect of the +N+I treatment in year one was associated with a more rapid root growth which could have reduced susceptibility to intermittent drought stress. Nodule biomass decreased between flowering and pod setting stages in the +I treatment whereas further increases in nodule biomass in the -I treatment may have led to competition for assimilates between nodules and developing pods. Based on these preliminary results we conclude that N application and seed inoculation can offer short-term benefits in unfavorable years without negative effects on yield in favorable years.

Influence of fungicide seed treatment on soybean nodulation and grain yield

Biological N2 fixation is a major factor contributing to the increased competitiveness of Brazilian soybeans on the international market. However, the contribution of this process may be limited by adverse conditions to symbiotic bacteria, such as fungicide seed treatments. This study aimed to evaluate the effects of the fungicides carbendazim + thiram and carboxin + thiram on soybean nodulation, plant growth and grain yield. Two field experiments were carried out in the Cerrado region of the State of Roraima, in a soil with a low organic matter content and no soybean bradyrhizobia. In 2005, seeds were treated with fungicide carbendazim + thiram and commercial inoculants containing the Bradyrhizobium elkanii strains SEMIA 5019 and SEMIA 587 and B. japonicum strains SEMIA 5079 and SEMIA 5080. In 2006, soybean seeds were treated with the fungicides carbendazim + thiram or carboxin + thiram and inoculated separately with each one of the four strains. The plants were evaluated for number of nodules and dry weight, shoot dry weight and total N accumulated in shoots 35 days after plant emergence, while grain yield and N grain content were determined at harvest. Both fungicides reduced soybean nodulation, especially in the presence of B. elkanii strains. The fungicide carbendazim + thiram reduced nodulation by about 50 % and grain yield by more than 20 % (about 700 kg ha-1), in the treatment inoculated with of strain SEMIA 587.

Cobalt and molybdenum concentrated suspension for soybean seed treatment

The concentrated suspension (CS), the basis of Mo trioxide, allows high Mo concentrations and is therefore a technical advance for seed treatment, since it allows the recommendation of the Mo at lower dosage than with the liquid solution formulations (LS). The purpose of this research was to evaluate the efficiency and doses of fertilizer with Mo and Co in concentrated suspension in comparison with liquid solution as well as fertilizers associated with phytohormones, applied in seed treatments, and their effect on soybean yield. Two experiments were carried out in the growing seasons of 2004/2005 and 2005/2006 at the Universidade Federal de Uberlandia (UFU).The first was conducted in an experimental area on the Fazenda Capim Branco, with six treatments and four replications: (1) Mo and Co (CS) - 22 g ha-1 + 1.08 g ha-1; (2) Mo and Co (CS) - 22 g ha-1 + + 1.08 g ha-1 + phytohormone -200 mL ha-1; 3) Mo and Co (LS), 20.7 g ha-1 + 4.13 g ha-1; 4) Mo and Co (LS), 20.7 g ha-1 + 4.13 g ha-1 + phytohormone -200 mL ha-1; (5) + control phytohormone-200 mL ha-1; and (6) control (free of Mo and Co in the seed treatment). The phytohormone consisted of: auxin (11 mg L-1) and cytokynin (0.031 mg L-1). The soybean cultivar Monsoy 8004 was used and a fertilization of 400 kg ha-1 of 02-20-20 NPK fertilizer was applied at sowing. Based on the results of the first experiment, the second was conducted on the Fazenda Floresta do Lobo, in Uberlândia, MG, evaluated in a randomized block design with nine treatments and four replications. The treatments consisted of Mo and Co (g ha-1) doses applied to soybean seeds, as CS formulation (15, 25, 35, 45, 60 and 0.74; 1.23; 1.72; 2.21; 2.95) and LS- (15; 20; 25 and 3.18; 4.25; 5.31), respectively, and the control (free of Mo and Co in the seed treatment). The variety Monarch was used, fertilized with 300 kg ha-1 of NPK fertilizer (03-32-06) at sowing; and 78 kg ha-1 (K2O) in topdressing 30 days after soybean emergence. The Mo and Co doses in the seed treatment with LS and CS resulted in higher soybean yields than in the control, from 20 g ha-1 Mo and 4.25 g ha-1 Co in liquid solution and 35 g ha-1Mo and 1.72 g ha-1 Co in the concentrated suspension.

In-furrow inoculation of soybean as alternative to fungicide and micronutrient seed treatment

Soybean is a major grain crop in Brazil, and yields can be considerably improved by inoculation with selected Bradyrhizobium strains. However, the incompatibility between inoculation and seed treatments with fungicides and micronutrients represents a major barrier to the achievement of high rates of biological N2 fixation. Inoculation practices that can alleviate the negative effects of agrochemicals must therefore be found and in-furrow inoculation seems to be an attractive alternative. This study reports the results of seven field experiments conducted in three growing seasons in Brazil; three in soils previously cropped with inoculated soybean (> 10(4) cells g-1 of soil of Bradyrhizobium), and four in areas where the crop was sown for the first time (< 10² cells g-1 of soil of Bradyrhizobium). The compatibility with fungicides and micronutrients was compared in seeds inoculated with peat or liquid inoculants, or treated with different doses of liquid inoculant in-furrow. In areas with established Bradyrhizobium populations, seed-applied agrochemicals did generally not affect nodulation, but also did not increase yields, while inoculation always increased N grain accumulation or yield, and N fertilizer decreased both nodulation and yield. Where soybean was sown for the first time, the seed treatment with agrochemicals affected nodulation when applied together with peat or liquid inoculant. In-furrow inoculation alleviated the effects of seed treatment with agrochemicals; the best performance was achieved with high Bradyrhizobium cell concentrations, with up to 2.5 million cells seed-1.

Diagnosis and recommendation integrated system (DRIS) of soybean seed oil content

The Diagnosis and Recommendation Integrated System (DRIS) can improve interpretations of leaf analysis to determine the nutrient status. Diagnoses by this method require DRIS norms, which are however not known for oil content of soybean seeds. The aims of this study were to establish and test the DRIS method for oil content of soybean seed (maturity group II cultivars). Soybean leaves (207 samples) in the full flowering stage were analyzed for macro and micro-nutrients, and the DRIS was applied to assess the relationship between nutrient ratios and the seed oil content. Samples from experimental and farm field sites of the southernmost Brazilian state Rio Grande do Sul (28° - 29° southern latitude; 52° -53° western longitude) were assessed in two growing seasons (2007/2008 and 2008/2009). The DRIS norms related to seed oil content differed between the studied years. A unique DRIS norm was established for seed oil content higher than 18.68 % based on data of the 2007/2008 growing season. Higher DRIS indices of B, Ca, Mg and S were associated with a higher oil content, while the opposite was found for K, N and P. The DRIS can be used to evaluate the leaf nutrient status of soybean to improve the seed oil content of the crop.

Genotypic variability in seed accumulation of foliar-applied molybdenum to common bean

The genotypic variability in molybdenum (Mo) accumulation in common bean seeds has been demonstrated in cases in which soil is the main Mo source, but this variability is yet unknown when Mo is foliar-applied. Therefore, seed Mo concentrations (SMoCc) and seed Mo contents (SMoCt) of 12 genotypes were determined in four experiments in the Zona da Mata, Minas Gerais, Brazil, in which plants were sprayed with 600 g ha-1 Mo. For comparison, two additional experiments without external Mo were conducted. Without Mo application, the average SMoCc was undetectable or 2.83 µg g-1, without significant differences among genotypes. On average, with Mo applications, SMoCc ranged from 14.7 to 25.0 µg g-1 and SMoCt, from 3.94 to 6.84 µg. 'Majestoso' was among the genotypes with the highest SMoCc in the four experiments. However, the large-seeded 'Jalo MG-65' and 'Carnaval' generally had higher SMoCt than the small-seeded 'Majestoso'. 'Ouro Negro' and especially 'Valente' were among the genotypes with the lowest SMoCc and SMoCt. The values of these variables were 61 and 90 %, respectively, higher for 'Majestoso' than those for 'Valente'. Our results suggest that common bean genotypes differ in their capacity to accumulate foliar-applied Mo in the seeds. Mo-rich seeds of large-seeded genotypes or of small-seeded of small-seeded genotypes with good capacity to accumulate Mo in seeds can be produced with relatively less Mo fertilizer.

Matriconditioning integrated with gibberellic acid to hasten seed germination and improve stand establishment of pepper and tomato

Emergence and stand establishment of tomato (Lycopersicon lycopersicum (L.) (Karsten ex Farw) and pepper (Capsicum annus L.) seeds are often slow and erratic, particularly under stress conditions. Field emergence trials sometimes have not responded to priming in pepper. This study examined the combined effects of matriconditioning and gibberellin application on the germination and stand establishment of pepper and tomato seeds. Pepper and tomato seeds were conditioned with a solid carrier, Micro Cel E, in the presence of gibberellic acid (GA) for 1, 2 , 3 and 4 days at 15 and 25ºC. The results showed that, in all cases, even under stress conditions, the combination of matriconditioning with GA was effective in improving germination and emergence of pepper and tomato. The germination time was, in average, reduced by 2 to 3 days by primed seeds. Thus, matriconditioning, during which germination is suspended, provides an unique means to rapidly and efficiently digest the endosperm by GA-induced enzymes and reduce the mechanical restraints of endosperm thus providing energy to start and sustain embryo growth.

Description of a pure seed fraction of oat through usual evaluations and radiographic images

The objective of this work was to evaluate the width and length incidence in a single seed fraction of oat [Avena sativa (L.)] cv. Cristal. The seeds were selected by a mechanical divider and by hand, and their correspondence to radiographic images in seeds with glumes and their caryopses. The width and length of the seeds with glumes and their caryopses were measured with electronic calliper, and their weight, with precision balance. Radiographic images of seeds with glumes were taken with an X-ray experimental equipment. The analyst selected seeds with glumes by the width and by the length previously determined and so with more weight, than that obtained by hand selection was slightly narrower, larger and lighter. The presence of the glumes masked the caryopses real dimensions (width and length), and conduced the analyst to select seeds that differed more by the width than by the length. The radiographic images showed the presence, or not, of caryopses inside the seed and its real dimensions. The mechanical partition method for seeds showed to be more efficient because the analyst subjectivity was not considered when the selection upon its dimensions was done. The X-ray analysis was a useful tool that complements the pure seed fraction selection as another factor of seed quality.

Grain yield and seed quality of soybean selected for high protein content

The objective of this work was to evaluate the effects of selection for high protein on seed physiological quality and grain yield of soybean. Four populations of BC1F4 and four of F4, each from a cross between a commercial variety and a line bearing high protein seeds, were used. The high protein content selection has a tendency to affect negatively the seed physiological quality. Estimates of correlation coefficients between protein content and grain yield were mostly negative but varied among populations. It is possible to obtain lines with high protein content, keeping the grain yield and the seed physiological quality of their respective recurrent progenitors.

Seed viability constants for Eucalyptus grandis

This work aimed to analyse Eucalyptus grandis W.Hill ex Maiden seed behaviour, under controlled deterioration, and to estimate viability equation constants for the species. Seeds were harvested in the growing season of 1999, and the moisture contents were adjusted from 11.3% to a range between 1.2 and 18.1% at 25ºC. The subsamples were sealed into laminate aluminium-foil packets, for storage in incubators at 40, 50 and 65±0.5ºC. The seeds presented orthodox performance, in which the constants for predicting seed longevity of E. grandis were K E = 9.661, C W = 6.467, C H = 0.03498 and C Q = 0.0002330. The usual and inverse relationship between water content and seed longevity was also observed. The lowest moisture content limit for application of the viability equation at 65ºC was 4.9%, estimated under hygroscopic equilibrium with 23% of relative humidity in the storage environment.

MGS Esmeralda: new large seed mungbean cultivar

Mungbean cultivar MGS Esmeralda was developed by Asian Vegetable Research and Development Center (Shanhua, Taiwan), as a result of crossing between the lines VC 1973A and VC 2768A. In ten trials conducted in the State of Minas Gerais, Brazil, it produced 13.5% more grains than 'Ouro Verde MG-2' (control cultivar), and its highest yield was 2,550 kg ha-1. The cultivar MGS Esmeralda is more susceptible to lodging, and its pods mature more uniformly than Ouro Verde MG-2 pods. One hundred-seed mass of 'MGS Esmeralda' ranged between 5.5 and 6.8 g. Both cultivars are susceptible to powdery mildew and cercospora leaf spot.

Seed priming and sulfur effects on soybean cell membrane stability and yield in saline soil

The objective of this work was to determine the effects of seed priming and sulfur application on cell membrane characteristics, seedling emergence, chlorophyll content and grain yield of soybean (Glycine max) in saline soil. A complete-block design in 4x3 factorial arrangement with three replicates was used to test four types of seed priming (water, auxin, gibberellin and non-priming) and three levels of sulfate availability (0, 70 and 140 kg ha-1 K2SO4). The soil had a silty loam texture with an electrical conductivity of 3.61 ds m-1, a pH of 8.2 and a saturation percentage of about 46%. Seed priming had significant effects on mean emergence rate (MER), emergence percentage, relative water content (RWC) of leaves, relative chlorophyll content, time of maturity, shoot length and grain yield. The highest values for these variables were observed in the priming treatments, except for the time of maturity. Sulfur application had significant effects on MER, shoot length, RWC, membrane injury index and grain yield. Priming treatments provide greater emergence rates and grain yields and interact sinergicaly with sulfur rates.

Subunit composition of seed storage proteins in high-protein soybean genotypes

The objective of this work was to quantify the accumulation of the major seed storage protein subunits, β-conglycinin and glycinin, and how they influence yield and protein and oil contents in high-protein soybean genotypes. The relative accumulation of subunits was calculated by scanning SDS-PAGE gels using densitometry. The protein content of the tested genotypes was higher than control cultivar in the same maturity group. Several genotypes with improved protein content and with unchanged yield or oil content were developed as a result of new breeding initiatives. This research confirmed that high-protein cultivars accumulate higher amounts of glycinin and β-conglycinin. Genotypes KO5427, KO5428, and KO5429, which accumulated lower quantities of all subunits of glycinin and β-conglycinin, were the only exceptions. Attention should be given to genotypes KO5314 and KO5317, which accumulated significantly higher amounts of both subunits of glycinin, and to genotypes KO5425, KO5319, KO539 and KO536, which accumulated significantly higher amounts of β-conglycinin subunits. These findings suggest that some of the tested genotypes could be beneficial in different breeding programs aimed at the production of agronomically viable plants, yielding high-protein seed with specific composition of storage proteins for specific food applications.

Desiccation, postharvest maturity and seed aging of tall oat-grass

The objectives of this work were to determine whether and at which seed physiological maturity stage the diquat desiccant affects the tall oat-grass (Arrhenatherum elatius) seed quality and yield, as well as the proper storage period between harvest and sowing. Diquat desiccation was evaluated in applications during milk or dough seed maturation stages. Seeds conventionally produced and stored under traditional storage conditions were used for the analyses. Seed samples were drawn every 30th day after harvest (DAH). After the 240th DAH, samples were drawn every 90th day up the to 690th DAH. The highest yield were obtained by desiccation applied at the beginning of the seed dough stage, with a satisfactory seed quality. Both final germination and seedling growth parameters achieved their maximum values between 180th and 240th DAH. Oat-grass seeds preserved satisfactory level of final germination (75%) up to 420th DAH. The application of diquat desiccant at the beginning of seed dough maturity stage can be a good solution for seed production of tall oat-grass. Early spring is the best sowing period for freshly harvested seeds of tall oat-grass regarding germination and seedling growth.

Genotype by environment interaction for seed yield per plant in rapeseed using AMMI model

The objective of this study was to assess genotype by environment interaction for seed yield per plant in rapeseed cultivars grown in Northern Serbia by the AMMI (additive main effects and multiplicative interaction) model. The study comprised 19 rapeseed genotypes, analyzed in seven years through field trials arranged in a randomized complete block design, with three replicates. Seed yield per plant of the tested cultivars varied from 1.82 to 19.47 g throughout the seven seasons, with an average of 7.41 g. In the variance analysis, 72.49% of the total yield variation was explained by environment, 7.71% by differences between genotypes, and 19.09% by genotype by environment interaction. On the biplot, cultivars with high yield genetic potential had positive correlation with the seasons with optimal growing conditions, while the cultivars with lower yield potential were correlated to the years with unfavorable conditions. Seed yield per plant is highly influenced by environmental factors, which indicates the adaptability of specific genotypes to specific seasons.