Effect of planting date on soybean yield in north of Paraná Region, Brazil

Abstract

This study was carried out in order to assess the response of some soybean cultivars (Glycine max (L.) Merrill) to planting dates. In general, the highest soybean yields were obtained when the plantings were made in October and November, and decreased with later plantings. Yields will be at a maximum when pod development and pod-filling stages occur between mid December and beginning February, if no drastic stress occurs during the stages of vegetative growth. Planting early, medium and late cultivars between mid October and mid December, decrease the impact of rainfall anomalies, which may occur during the periods of pod formation and pod filling, on soybean yields. The yield reduction observed as the planting is delayed beyond the planting date for maximum yield, is explained by the reduction in the availability of water to which these late plantings are exposed, in addition to the depressive photoperiod effect. It was determined the regression equations between the emergence date and yield for the cultivars Paraná, Bossier and Santa Rosa. Calculations of maximum points of each equation allow to determine the emergence dates that resulted in the maximum yield for the three cultivars. Running this procedure for plant height produce similar results for this variable.