CONICET | Buscador de Institutos y Recursos Humanos

Wheat crop response to sulfur depends on nitrogen level, genotype and environmental conditions, demonstrating strong genotype x environment x nutrients interactions. The agronomic use efficiency of both nutrients has not been evaluated in a wide range of modern genotypes, differing in their cycle length and baking quality. The aim of this study was to analyze the effect of N and S fertilization on yield components and use efficiency of both nutrients in 24 modern, high-yielding bread wheat genotypes (including long and short crop cycles), grown in contrasting environments in the Humid Pampa of Argentina. Two experiments were conducted under contrasting seasonal conditions on the soil type mollisols in Azul, Buenos Aires. Significant effects of N (range of 15-200 kg N ha-1) on grain yield were observed in all genotypes. By contrast, responses to S (30-100 kg S ha-1) were found only at high N level in low soil fertility environments, differing between long and short cycles. Genotype by fertilization interaction was significant in the environment with higher soil fertility. S addition improved N recovery efficiency (0.15 versus 0.32) and agronomic efficiency of the available N (84 versus 93 g g-1) in the poor fertility environment, characterized by their N and S deficiency and moderate level of organic matter. Grain N recovery efficiency was largely explained by increases in grain number, while S recovery was also associated to increases in grain nutrient concentration. We conclude that genotype and environment strongly altered fertilizer use efficiency, providing valuable information for ranking genotypes and optimizing site-specific management of wheat crops in the Humid Pampa of Argentina. Grain S% may be useful as a physiological marker for selection of bread wheat genotypes with high apparent S recovery.

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