Prediction of phenological stages of six maize (Zea mays L.) hybrids based on required growing degree days

Abstract

An experiment was under taken at the Agricultural College farm, Bapatla during two consecutive years of rabi 2016-17 and 2017-18. The experiment was laid out in randomized block design with six treatments in four replications. Maize hybrids 900M Gold, DKC 9142, DKC 9120, DKC 9081, DKC 9042 and Pinnacle showed significant differences in plant height, stem girth, number of leaves and initiation of reproductive organs. All maize hybrids grew to its maximum height in 77 to 84 calendar days after sowing with a thermal requirement of 1131 to 1221 °cd. Maize hybrids attained maximum stem girth (2.63 to 2.84) in 70 calendar days with thermal requirement of 1033 0Cd. Significantly higher stem girth was found in pinnacle and DKC 9142 followed by 900M Gold and DKC 9120 in both the seasons of crop growth. The maximum number of leaves was attained at 70 DAS with cumulative heat units of about 1028 0Cd. During rabi 2016 to 17, DKC 9142 took less number of days (28.50) for tassel primordial initiation followed by pinnacle (29.0), DKC 9042 (29.25) and DKC 9120 (29.50) and 900MGold took more (30.00) followed by DKC 9081(29.75). During rabi 2017 to 18, it was less in DKC 9142 (28.38) followed by DKC 9042 (29.00) and more in 900M Gold (29.38), Pinnacle (29.38) and DKC 9081 (29.25). During tassel primordial initiation, the heat units accumulated was 467.0 0Cd for DKC 9081 and 900M Gold during rabi 2016 to 17, while in rabi 2017 to 18 it was 488.7 °Cd for DKC 9042, 503.3 0Cd for pinnacle and 900M Gold, 503.8 0Cd for DKC 9120 and 517.6 °Cd for DKC 9081.