Does Chemical Desiccation and Harvest Time Affect the Physiological and Sanitary Quality of Soybean Seeds?

Abstract

The use of desiccants may result in seeds with high physiological and sanitary quality due to the shorter period of exposure to field adverse conditions before the maturity stage for harvest. This study evaluated the effect of chemical desiccants and harvest times on the physiological and sanitary quality of soybean seeds. The experiment consisted of a randomized block design, arranged in a factorial scheme (4 × 3) + 1, with four replications. The first factor corresponded to four desiccation (grammoxone-2 L ha -1 , glufosinate -2 L ha -1 , reglone-1.5 L ha -1 , and saflufenacil-40 g ha -1 ) applied at the R 7.1 phenological stage (physiological maturity and 65% moisture with three harvest times (0, 7, and 14 days after the R 8 phenological stage) and additional treatment (control, application of water only, and harvest at the R 8 stage), with four replications. The use of the grammoxone desiccant and seeds harvested at seven days after the R 8 stage resulted in soybean seeds of the highest physiological quality, as observed for the variables germination, moisture damage, mechanical damage, and incidences of Colletotrichum sp., Phomopsis sp., Penicillium sp. Fusarium sp., Cercospora kikuchii, and Alternaria sp. Seeds harvested at the R 8 + 14 stage had the greatest losses in seed quality. The use of ammonium glufosinate and saflufenacil as desiccants is not recommended due to the reduction in the physiological quality of soybean seeds.RESUMO -O uso de dessecantes pode permitir a obtenção de sementes com máxima qualidade fisiológica e sanitária, devido o menor período em que as sementes ficam expostas as condições adversas no campo aguardando o estádio de maturação para colheita. O objetivo neste trabalho foi avaliar o efeito de dessecantes químicos e épocas de colheita sobre a qualidade fisiológica e sanitária em sementes de soja. O ensaio foi realizado em delineamento em blocos casualizados, disposto em esquema fatorial (4 × 3) + 1, sendo quatro herbicidas para a dessecação (gramoxone -2 L ha -1 , glufosinato -2 L ha -1 , reglone -1,5 L ha -1 , saflufenacil 40 g ha -1 ) aplicado no estádio fenológico R 7.1 (maturidade fisiológica e 65% de umidade), com três épocas de colheita (0; sete e 14 dias após o estádio fenológico R 8 -maturação plena), mais o controle (ausência de dessecante e colhida em R 8 ), com quatro repetições. O uso do dessecante gramoxone e as sementes colhidas sete dias após R 8 proporciona maior qualidade fisiológica de sementes de soja, conforme observado nas variáveis germinação, danos por umidade, danos mecânicos e a incidência de Colletotrichum sp., Phomopsis sp., Penicilium sp., Fusarium sp., Cercospora kikuchii e Alternaria sp.. A colheita de sementes no estádio R 8 +14 promove as maiores perdas na qualidade das sementes. O uso de glufosinato de amônio e saflufenacil como dessecantes não são recomendados, devido à redução na qualidade fisiológica das sementes de soja.Palavras-chave: Glycine max. Herbicidas. Maturidade fisiológica. Vigor.

Metabolic changes, agronomic performance, and quality of seeds in soybean with the pat gene after application of glufosinate

“…For the application of this herbicide as a preharvest desiccant in soybean (not tolerant to glufosinate), negative effects on the quality of the seeds produced may or may not be observed, with variations due to the stage of application and rate (Pereira et al 2015;Zuffo et al 2019). Studies evaluating the quality of LL soybean seeds following application of glufosinate are scarce.…”

Glufosinate and diquat in pre-harvest desiccation of soybean at four phenological stages, and their impact on seed quality

“…However, the results may vary according to the production environment, the cultivar, and the predominant climatic conditions. The application of glufosinate (Delgado et al, 2015;Botelho et al, 2019;Zuffo et al, 2020) or diquat (Finoto et al, 2017;Ergin and Kaya, 2020) can affect soybean seed quality, especially at stages before R7. Thus, it is recommended, as a precautionary principle (in view of the potential variations), to apply pre-harvest desiccants, such as glufosinate, paraquat, carfentrazone, and diquat, in seed production fields exclusively at R7.3, as shown by Pereira et al (2015b).…”

“…Other authors have also reported the negative effects of the application of different desiccant herbicides, earlier than R7, on soybean yield and other parameters (Cella et al, 2014;Coltro-Roncato et al, 2015). Glufosinate may or may not have negative effects on seed quality, depending on the application timing and dose (Pereira et al, 2015a;Botelho et al, 2019;Zuffo et al, 2020). Many stressors, such as herbicides that cause changes in soybean physiology, can affect the seed quality (Albrecht et al, 2012;Marchi et al, 2021).…”

Sunflower seed germination and storability response to chemical desiccation

“…By drying out green portions of the plant, chemical desiccation makes mechanized harvesting easier (Miklič et al ., 2012) . Desiccation is especially beneficial in seed production of crops such as sunflower (Čanak et al ., 2011) and soybean (Zuffo et al ., 2019) . The optimal moment for performing desiccation is at physiological maturity when seeds reach maximal viability and vigour .…”