Foliar fungicide based on strobilurin, production and physiological quality of soybean seeds

Author(s)

Taís Leite Ferreira Pinto

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2010-12-03

Examining board members

Silvio Moure Cicero; Jose de Barros França Neto; Francisco Carlos Krzyzanowski; Gilda Pizzolante de Pádua; Edila Vilela de Resende Von Pinho

• Advisor: Silvio Moure Cicero

Abstract

Unfavorable weather conditions, during the late soybean maturation, have caused problems in seed quality due to \"forced maturation\" or premature plant death, which can result in the appearance of green seeds. Strobilurin group fungicides have physiological effects on plant performance, reflected in production, mainly by delaying the plant senescence. This study aimed to evaluate the effect of fungicides, especially the strobilurin group and rust disease on yield and quality of soybean seeds, with focus in the occurrence of green seeds. The treatments were control and applications of flutriafole + thiophanate, methyl, pyraclostrobin + epoxiconazole and metconazole fungicides, and the products were applied in R2 and R5.1 growth stages, individually and also in combined applications. The experiments were carried out under field conditions in three locations (Alto Garças-MT, Londrina-PR and Piracicaba-SP) during the 2007/08 and 2008/09 crops. Three different cultivars were used for each location. Seed quality was evaluated by means of the germination, tetrazolium, accelerated aging, electrical conductivity, sanitary, radicle and hypocotyl length tests, and also by means of chlorophyll fluorescence in the seeds of the second crop year. Analyses were performed immediately after harvest and after seven months of storage. The experimental design was randomized blocks with seven treatments and three cultivars, location and year for each trial. Means were compared by Tukey test at 5% probability. The strobilurin fungicide does not affect the production and has no direct effects on seed quality and in the occurrence of green seed. Under favorable weather conditions for seed maturation, the severity of soybean asiatic rust disease interferes with the production, but does not influence on its physiological potential. The soybean asiatic rust disease associated with unfavorable weather conditions during the final stage of maturation provides the occurrence of green soybean seeds, that compromises the vigor after storage. (AU)