Determination of Seed Physiological Maturity of Ipomoea reptans Poir. Based on Phenology, Seed Quality, and Heat Unit Accumulation

Abstract

Kangkong (Ipomoea reptans Poir.) seeds have different colors at harvest due to differences in the seed maturity level, hence, differences in seed quality. Therefore, this study aimed to obtain information about the phenology of flowers, fruits, seeds, and to determine the appropriate heat unit accumulation to reach the seed physiological maturity of kangkong when the maximum seed quality is achieved. The experiment was arranged in a randomized completely block design with one factor. The experimental factor was the seed harvest age consisted of 15 levels, starting from 16 days after anthesis (DAA) or 79 days after planting (DAP) to 30 DAA. The anthesis occurred at 63 DAP. The results showed that the seed physiological maturity of kangkong cv KK02 was achieved at 25 DAA with the characteristics of brownish fruit color, white seeds, and the seeds turned dark brown after drying. At 25 DAA, the seed moisture content was the lowest while the seed dry weight, seed viability, and seed vigor reached their maximum. The heat unit of kangkong cv KK02 at the seed physiological maturity was 1,668.50 °Cd. It is suggested that the kangkong seeds are harvested at 25 DAA with a heat unit of 1,668.50 °Cd.