Acúmulo e partição de matéria seca e nutrientes de cultivares de soja, semeadas em duas épocas

Abstract

New soybean cultivars are introduced in the agricultural market with different accumulations and partition of dry matter (DM) and nutrients, which may influence the management of fertilization, but this was still little explored by the research. The objective of this work was to evaluate the accumulation and partition of DM and nutrients of soybean cultivars, sown in two seasons. Twelve soybean cultivars (Raio, 95R51, 54I52, Elite, 5947, Alvo, 7062, 5909, Potency, 6700, Icon and Antares), seeded on 11/5/2016 and 12/08/2016, were evaluated. The experiment was fielded in Passo Fundo, RS. The experimental design was in a randomized block with four replicates. Leaf MS (MSH), stem (MSH), vegetable (MSL), the sum of the parts (MSHFL) grain yield (RG) and total MS (MST = MSHFL + RG) were evaluated at physiological maturation. The nutrient content was evaluated in the diagnosis leaf, collected in R2; the grain and the remainder of the aerial part collected on the day of harvest. The MSHFL varied inversely to the GR, at both sowing times. The RG constitutes the major part of the MST (34 to 50%), followed by MSH (19 to 33%), MSF (14 to 22%) and MSL (12 to 16%) in plants seeded on 05/11. In plants seeded on 08/12 the RG represents 40 to 52% of MST, followed by MSH (19 to 29%), MSF (13 to 19%) and MSL (13 to 16%). The highest CI was of the cultivars Raio and 54I52 (First sowing season) and Target and Radius (Second sowing season), and the highest GR was 54I52 (First sowing season) and the Target (Second sowing season). The cultivars with higher CI of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, manganese, zinc, iron, boron and copper were: Radius; Lightning; 5947 and 5909; 5909; 54I52; 54I52 and 5909; Lightning; Lightning; Lightning; Lightning; and Ray, again, in the first sowing season e: 6700; Icon; Icon; Elite; 6700; 6700; Antares; 7062; Antares; 7062; and Antares, respectively in the second sowing season. The nutrient content in the straw has influence of the cultivar, for all the elementes, with the exception of zinc, boron and copper in the first season and magnesium in the second sowing season. The content in the grain varies less than the straw. Nitrogen, phosphorus, potassium, sulfur, zinc and copper in both sowing times, and magnesium, manganese and iron in the second sowing season did not have a difference between the cultivars. The amount of nutrients extracted in the straw and exported by the grain differed between the cultivars at both sowing times, being a consequence of the nutrient content in those organs and the amount of straw and grain produced.