Relationship between soybean seed coat lignin content and resistance to mechanical damage

Abstract

Mechanical damage is the most important factor that reduces soybean seed quality at harvest and processing. Careful handling of the seed during those phases may prevent the occurrence of mechanical injury. Some cultivars have shown certain genetic resistance to mechanical abuse, which is a desirable characteristic for seed quality. The causes of mechanical damage as well the procedures to evaluate it are well known. The objective of this research was to investigate the genetic mechanism of the observed resistance to mechanical damage so that soybean breeders may screen for the character. Twelve cultivars of known performance related to mechanical damage were used: resistant - Doko, FT-2, IAS-5 and Parana ; moderately resistant - Santa Rosa, IAC-8, FT-10 and Bossier; susceptible Davis, Paranagoiana, Savana and IAC-2. Lignin content of the seed coat was determined and its results correlated with the index of resistance to seed mechanical damage obtained by the pendulum test. The coefficient of determination (r 2 ) between these two parameters was 0.90, which was highly significant, meaning that the higher the level of lignin content in the seed coat, the higher the level of resistance to mechanical damage. These results directly implicate lignin content of the seedcoat as the genetic trait that should be used to screen for genotypes that will resist to mechanical damage.