Resistance to Asian soybean rust in soybean lines with the pyramided three

No abstract

No abstract

The aim of this study was to evaluate the effect of industrial seed treatments on the physiological potential of soybean seeds over storage. Four mixtures of agrochemical products in association with two fertilizers were tested. The agrochemical product mixtures were carbendazim/thiram + imidacloprid/thiodicarb; pyraclostrobin, thiophanate-methyl, and fipronil; thiophanate-methyl/fluazinam + bifenthrin/imidacloprid; and metalaxyl-m/fludioxonil + thiamethoxam. The two fertilizers were 7% N, 16% P2O5, 0.6% Co, and 2.5% Mo; and 1% Co, 10% Mo, and 7% P2 O5. The experiment was carried out in a completely randomized design in a split-plot arrangement in time, with four replications. The treatments were allocated in the plots, while the storage periods (0, 30, 60, 90, and 120 days) constituted the split-plots. The following tests were carried out in each period: first count of germination, germination, accelerated aging, emergence speed index in sand substrate, and final seedling emergence in sand substrate. Seed germination and vigor declined over the storage period, especially after industrial treatment. Pesticide mixtures of a carbendazim/thiram fungicide base and an imidacloprid/thiodicarb insecticide base most impaired seed physiological potential throughout storage, regardless of fertilizer use in the industrial treatment.

Bio-activators such as thiamethoxam have been used to increase the productive potential of plants, by means of metabolic and plant morphology modifications. Nevertheless, very little is known regarding the effectiveness of this insecticide when incorporated into lower quality level soybean seeds, particularly during storage. The objective of this work was to assess the influence of thiamethoxam on the physiological potential of soybean seeds with different initial vigor levels during four storage periods. Three vigor levels of cultivar Anta-low (35%), medium (70%) and high (85%) vigor-of soybean seeds were utilized in this experiment. The experimental design was completely randomized in a 3 × 2 × 4 factorial scheme-3 levels of vigor (low, medium and high); 2 seed treatments (with and without thiamethoxam) and 4 storage periods (0, 30, 60 and 90 days). The analyzed variables were: germination, first germination count, accelerated aging test, seedling length and emergence speed index. Thiamethoxam-treated soybean seeds benefit the physiological potential of both medium and high vigor seeds during storage up to 30 days. Whereas, the use of thiamethoxam was shown to be ineffective in improving the physiological quality of initial low vigor seeds.