Physiological Quality of Soybean Seeds Depending on the Preharvest Desiccation

Abstract

Depending 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.

Quality of soybean seeds with different lignin content obtained from desiccated plants

“…Finale® is a commercial formula for glufosinate ammonium that shows an easier translocation compared to paraquat and diquat (Lacerda et al, 2005). Since water is the principal transportation agent to intern tissues, the higher the water content in the seeds, the higher the possibility of damage is caused by the desiccants (Pereira et al, 2015). Therefore, the application of Finale® when seeds had 50% of water content may have favored the product translocation to the interior of the cells, causing some phytotoxic effect.…”

“…The decision of using desiccants in seeds production fields should be careful, because some herbicides used to desiccate plants leave residues that may favor the fungus development and reduce seeds vigor. The occurrence and intensity of the damages are directly related to the environmental conditions at the time of application, to the seeds development stage, and to the seeds tegument characteristics (Pereira et al, 2015).…”

Rendimento por peneiras de classificação e vigor em resposta às épocas de colheita de sementes de soja

“…No teste de tetrazólio (Tabela 5) observou-se que o resultado do vigor depende da interação entre cultivares e épocas de colheita. A cultivar NA 5909 RG manteve seu vigor ao longo das épocas de colheita, corroborando com os resultados obtidos por Pereira et al (2015a) em trabalhos conduzidos com a mesma cultivar que manifestaram manutenção da qualidade fisiológica, demonstrando maior potencial de manutenção de vigor.…”

Implicações da época de colheita sobre a qualidade fisiológica de sementes de soja

“…Daltro et al (2010), em experimento realizado com diferentes épocas de dessecação e produtos, não encontraram diferenças entre os tratamentos para o vigor pelo teste de tetrazólio. De acordo com Pereira et al (2015b), a manutenção da qualidade fisiológica é dependente da cultivar, pois em trabalhos realizados com diferentes cultivares observaram que a cultivar NA 5909 RG manteve sua viabilidade independentemente da situação de colheita, antecipação proporcionada pelo uso de dessecante, que apresentou 92% de sementes viáveis ou atraso da colheita, apresentando 90%.…”