PHYSIOLOGICAL QUALITY OF SOYBEAN SEEDS DEPENDING ON THE PREHARVEST DESICCATION

ABSTRACTDepending on the cultivar, the use of desiccants in the preharvest can favor maintenance of physiological quality. The objective of the study was to assess the physiological quality of soybean seeds as due to the use of apreharvest desiccant and desiccation time in two harvests (2011/12 and 2012/13). The treatments were five soybean cultivars, two growth stages of application, a control (without desiccant application), and three desiccants (glufosinate-ammonium, carfentrazone-ethyl and paraquat) (2011/12 harvest). In the 2012/13 harvest the carfentrazone-ethyl desiccant was replaced by diquat. The physiological quality of seeds was assessed by the percentage of viability and vigor (cold test, tetrazolium test and accelerated aging test). In 2011/12 harvest, there was an early harvest in six days with the use of glufosinate-ammonium and paraquat desiccants, when desiccation was done in stage R7.1, with maintenance of seed quality; however it was dependent on the cultivar. In the 2012/13 harvest there was no early harvesting due to the presence of rain in the preharvest and the use of desiccation did not affect the physiological quality of the seeds either. Cultivar NA5909 RG was more tolerant to remaining in the cultivation environment and maintained higher viability than 90% and greater vigor of 71% by the cold test compared to cultivar BMX Turbo (2011/12 harvest). It is concluded that desiccation can be a viable alternative to the soybean early harvesting, but it depends on the cultivar, the time of desiccation, the active principle of the desiccant and the absence of rain in preharvest