Thermal requirements and heat use efficiency of Brassica cultivars under varying sowing environments and row orientations

Abstract

A field experiment was conducted at Research Farm, School of Climate Change and Agricultural
Meteorology, PAU, Ludhiana to assess the heat units required by different phenological stages of
Brassica cultivars. The duration of phenological stages and accumulation of agro-climatic indices
(GDD, PTU and HTU) were greatly reduced with delay in sowing. Among the dates of sowing, the
highest agro-climatic indices accumulation was observed in 7th October as compared to 17th and 27th
October sown crop. Earlier sown crop had significantly highest heat use efficiency at flowering
stage (0.86 g/m2/°C/day). Among the cultivars, PBR 357 was observed highly efficient in heat use
as compared to GSC 7 and PC 6 cultivars. Among the row orientations, the highest heat use efficiency
was observed in E-W sown crop (0.37, 0.82 and 0.80 g/m2/°C/day) during vegetative, flowering
and pod filling stages respectively. The study concluded that alteration in sowing time and
appropriate row orientation are highly effective in improving heat use efficiency of Brassica cultivars
under changing climatic scenarios.