Determining physiological maturity for optimal seed quality and reduced yield loss in foxtail millet (Setaria italica (L.) P. Beauv.)

The present study aimed to determine the right stage of physiological maturity (PM) in foxtail millet cultivars (‘Suryanandi’ and ‘SiA 3156’) during two post-rainy seasons. The seed formation/developmental phase required about one week after flowering in year 1 and two weeks in year 2 in both cultivars, due to varying climatic parameters. The maturation of seeds progressed gradually, with a loss in moisture and gain in hardness, test weight and seed yield, during subsequent harvests at weekly intervals, which continued until 35 days after anthesis (DAA) (year 1) and 42 DAA (year 2) in both cultivars. The seed quality traits reached their maximum at 35 DAA during year 1 and thereafter declined gradually; the decline was more prominent in the case of aged seeds, indicating that seed viability would be lost faster due to delayed harvests. During year 2, the seed quality traits were at their maximum in the harvest at 42 DAA. Due to significant reduction in quality traits at a faster rate at later stages of harvest, the polynomial regression analysis predicted maximum quality of seeds at 38 DAA. The study found that the seeds reached the right stage of PM at 35 DAA in the year 1 and at 38 DAA during year 2 in both cultivars, providing valuable insights that PM generally occurs between 35 and 38 DAA, while the optimal harvest window is between 35 and 42 DAA during the post-rainy season in foxtail millet. At PM, the panicles turn brown, the seeds become hard, shiny, pale-yellow with elliptic streaks and a dark-brown depression develops at the hilar end and these act as visual indicators for the optimal time of harvest in foxtail millet.