Canola physiological, growth and yield response to boron application affected by heat stress due to late planting dates

A field experiment was carried out to study the yield and physiological responses of rapeseed (Brassica napus L.) to boron application and high temperature stress due to late planting, in Ramin Agriculture and Natural Resources University of Khuzestan at 2013-2014. The experimental design was a split plots design in RCBD with four replications. Planting dates (18 November, 3 December, 17 December and 30 December) were placed in main plots and boron application treatments (control, 10 kg B.ha-1 incorporated with soil, boron spraying at 8 leaf stage and budding stages) were placed in sub plots. Planting date had significant effect on relative water content (RWC), cell membrane stability, peroxidase enzyme activity, leaf area index (LAI), canopy’s temperature, grain yield and dry matter. In addition, boron application had significant effect on LAI, peroxidase enzyme activity and yield. Late planting caused to decrease the grain yield and dry matter related to increased canopy’s temperature at flowering stages. Delayed planting from 18 November to 30 December, result in decreased grain yield about 60.5 percent. Boron application incorporated with soil caused to increased grain yield about 23 percent in comparison to control. High temperature stress due to late planting caused to decreased RWC, cell membrane stability and LAI in flowering stage. Generally, highest grain yield (4579.7 kg.ha-1) was obtained from planting at 18 November and 10 kg boron.ha-1 incorporated with soil, and lowest grain yield was obtained from planting at 30 December and without boron application.