Evaluation of seed quality based on changes of internal substances during tobacco seed (Nicotiana tabacum L.) development

Seed quality is closely associated with internal substances during seed development. Tobacco seed varieties Honghua Dajinyuan (HD) and Yunyan97 (Y97) had higher viability and vigor when harvested from 31 to 33 days after pollination (DAP), subsequently decline slightly on 35 DAP. From 7 to 35 DAP, the moisture content of HD and Y97 decreased sharply from 90 to 30%, and abscisic acid declined more than 80% totally in seeds. Accumulation of oil and protein was accompanied with the consumption of soluble sugar and starch, especially from 7 to 23 DAP. In addition, crude fiber and arginine exhibited an increasing trend, while ash and lysine significantly decreased from 7 to 23 DAP. Generally, the germination percentage (seed viability) in HD and Y97 seed was related to oil, moisture, soluble sugar, protein, starch, ABA, lysine, arginine, seed weight and seed coat color; however, only moisture, oil and protein had a significant correlation with vigor index (seed vigor). Thus, seed viability could be applied to estimate the relationship between internal substances and seed quality, and predict the optimum seed harvest time of tobacco.