Crescimento e desenvolvimento de cultivares de soja em diferentes épocas de semeadura

Abstract

The accumulation of dry mass, productivity and growth rates of four soybean cultivars based on the accumulated thermal sum, with sowing at different times, were evaluated in Red-yellow Latosol, in the 13/14 and 14/15 crops in the Middle region North of Mato Grosso. The cultivars TMG 132 RR, GB 874 RR, MSOY 8866 and MSOY 8757, both of medium-late cycle, were evaluated in five sowing dates for 13/14 (between 18/10/27/11/13) and four for 14 / 15 (between 18 / 10-17 / 11/2015), with decendial intervals. Growth rate (TCC), relative growth rate (TCR), net assimilation rate (TAL) and absolute growth rate (TCA) were determined. To obtain the thermal sum, the Ometto method was used with minimum and maximum basal temperatures of 14 and 36 ° C, respectively. The correlations between growth rates and GDD were expressed by third order polynomials, with correlation percentages above 65%. The first sowing season (18/10) provided a higher average of the morphometric parameters and productivity in the 13/14 crop, however in the next harvest the yield was higher in the second, third and fourth seasons.