Response of Soybean Yield to Planting Density in Environments of Contrasting Productivity
The increase in the cost of soybeans has led to growing concern about the optimum density of the crop. For this reason, the objective of this work was to quantify the response of growth and yield to the density of sowings in contrasting productivity environments of Uruguay. The response in yield, number of grains per square meter (NG), weight of a thousand grains (PMG) and maximum IAF (IAF_max) in planting densities of 10 to 60 pl m-2 was evaluated in three environments of different potential: limiting environment (AL), intermediate environment (AI) and high environment (AA), two sowing dates and two years. The average yield was 2239, 3327 and 4139 kg ha-1 for the AL, AI and AA respectively. Yield response was observed only below 30 pl m-2. In two of the six situations the yield remained stable between 10 to 60 pl m-2. No differences were found between the environments in regard to the plant optimum where yield is maximized. NG and the PMG showed stability for the range of densities evaluated. The IAF_max exceeded the critical values in most environments, with the exception of the year with the lowest water availability in the LA. These results indicate that it is advisable that the density planted is higher than the minimum where yield reduction does not occur, in order to contemplate the risks due to unpredictable adverse conditions at the time of implantation.