Quality and chemical composition of soybean seeds witdifferent lignin contents in the pod and seed coat subjecteto weathering deterioration in pre-harvest

Abstract

Soybean seeds may show different responses to weathering deterioration depending on the intrinsic characteristics of the genetic material and the intensity and duration of the rainfall period. This study aimed to evaluate the effect of pre-harvest weathering deterioration on the quality and chemical composition of soybean seeds with different lignin contents in the pod and seed coat. The percentage of weathering damage was evaluated by the tetrazolium test, X-ray test, lignin content in the pod and seed coat, germination, accelerated aging, seedling emergence, seed health test, and oil, protein, and chlorophyll contents. The experimental design was completely randomized in a 7×3 factorial scheme, that is, seven cultivars and three rainfall volumes (0, 54, and 162 mm), simulated when 95% of the pods had a mature color. The physiological and sanitary quality of soybean seeds reduces with an increase in pre-harvest rainfall. Soybean seeds from cultivars with higher lignin contents in the pod present a higher tolerance to pre-harvest weathering deterioration and provide seeds of better physiological quality. Seed oil and protein content is reduced in some cultivars as rainfall increases. Plants with higher lignin contents in the pods produce seeds with a lower incidence of the fungus Cercospora kikuchii and lower chlorophyll content when associated with pre-harvest rainfall.