Energy requirements for attainment of different phenological stages in broccoli inbreds

Abstract

The field experiment comprised of three broccoli inbreds was carried out to assess the requirement of thermal energy, helio-thermal units, photo-thermal units, relative temperature, disparity and thermal use efficiency for days to 50% head initiation, days to 50% head maturity and duration of head maturity at CCS Haryana Agricultural University, Hisar during winter seasons of 2013 and 2014. The results revealed that broccoli crop in general required 813.7, 168.1 and 981.8 (°C day h) thermal units, 5161.1, 705.4 and 5866.5 (°C day h) heilo-thermal units, 8600.7, 1713.9 and 10314.5 (°C day h) photo-thermal units and 4042.2, 1996.6 and 6038.8 (°C day h) relative temperature disparity for head initiation, duration of head maturity and head maturity. Minimum thermal use efficiency (14.3°C day h) was measured for days to 50% head maturity followed by days to 50% head initiation (17.30°C day h) and duration of head maturity (83.44°C day h). Genotypic differences also observed for requirement of thermal energy in attainment of different phenological traits in broccoli. Marketable curd yield expressed significant positive correlation with heat unit consumed in both years. The R2 values of regression equation could explain the variation between 72-81% of the total variation in production of curd in broccoli.