Studies on key seed physico-chemical factors and climatic variables regulating hardseededness in green gram (Vigna radiata L.) genotypes

Context Green gram (Vigna radiata) is an important source of plant-based dietary protein. ‘Physical dormancy’ or ‘hardseededness’ is prevalent in many released varieties of green gram in India. Green gram seeds exhibit a variable proportion of hard seeds that do not imbibe water. Presence of hard seeds results in uneven germination, lower field emergence and leads to poor yield. Hardseededness is primarily attributed to thick impermeable seed coat, lignin content, and structural carbohydrates, which is controlled genetically as well as by prevailing environmental interactions. Aim To identify the major biochemical and growing conditions regulating the hardseededness in green gram. Methods Ninehard seeded (HS) and nine non-hard seeded (NHS) genotypes of green gram were evaluated for variation in hardseededness and physico-chemical parameters during two consecutive monsoon and summer season. Key results Hardseededness varied significantly between HS and NHS genotypes as well as between the growing seasons. Physico-chemical parameters like lignin content, cellulose, hemicelluloses, total phenol, and calcium content varied significantly among HS and NHS genotypes and also between monsoon and summer produced seeds. Conclusions Green gram genotypes produced in summer season exhibited lower proportion of hard seeds compared to those grown in the monsoon season. This may be due to higher atmospheric temperature at the time of seed maturity as well as relatively lower lignin, calcium, phenol, and structural carbohydrate content in varieties. Implications Our findings indicated that the summer season may be preferred over monsoon for production of quality seeds of identified hard seeded green gram varieties.