Energy indices and phenophase development in brassica: Evaluation of various energy indices in relation to phenophase development of brassica species

The ability of six different energy Indices based on radiation, thermal units, pan evaporation and potential evapotranspiration to predict phenophase development of three Brassica species grown at Hisar over three years was studied. The Indices were accumulated over various growth stages; sowing to vegetative, sowing to bolting, sowing to termination of flowering on main shoot and sowing to maturity in three species. When photosynthetically active radiation was summed over the period between sowing to termination of flowering on main shoot, it generally proved to be better index to predict phenophase development than the rest of the indices. The comparison of the coefficient of variation computed for all six indices over whole crop season (sowing to maturity) showed little variation. However, the index based on photosynthetically active radiation (PAR) when considered for entire crop season proved best over other indices and yielded least variation indicating Its better applicability.