Department of Vegetable Science, CCS Haryana Agricultural University, Hisar 125004
The field experiment comprised of three broccoli inbreds was carried out to assess the requirement ofthermal energy, helio-thermal units, photo-thermal units, relative temperature, disparity and thermal useefficiency for days to 50% head initiation, days to 50% head maturity and duration of head maturity at CCSHaryana Agricultural University, Hisar during winter seasons of 2013 and 2014. The results revealed that broccolicrop 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 (°Cday h) relative temperature disparity for head initiation, duration of head maturity and head maturity. Minimumthermal use efficiency (14.3°C day h) was measured for days to 50% head maturity followed by days to 50% headinitiation (17.30°C day h) and duration of head maturity (83.44°C day h). Genotypic differences also observed forrequirement of thermal energy in attainment of different phenological traits in broccoli. Marketable curd yieldexpressed significant positive correlation with heat unit consumed in both years. The R2 values of regressionequation could explain the variation between 72–81% of the total variation in production of curd in broccoli.
Broccoli, heat unit, inbred, thermal use efficiency, thermal requirement
