Response of cauliflower (Brassica Oleracea L. Var. Botrytis) growth and development after curd initiation to different day and night temperatures

Two experimental runs were conducted to assess the response of the growth and development of cauliflower (brassica oleracea l. var. botrytis) cv. nautilus f1 hybrid after curd initiation to different day and night temperatures in saxcil growth environmental cabinets,which were set to run at 24/12°c,12/24°c,20/16°c,16/20°c,20/20°c (1st run) and 24/20°c,20/12°c and 20/16°c (2nd run) with a total irradiance of 441 μ mols m-2 s-1 (90 watts m-2) at the school of biological sciences,university of reading,united kingdom. greater rates of curd growth (curd length,diameter,fresh and dry weights) were achieved at warmer night temperatures than day temperatures,whilst greater leaf and stem growth (leaf area,stem length,fresh and dry weights) were achieved when day temperatures were warmer than night temperatures,even with the same mean temperatures. greater curd growth (curd length,diameter,fresh and dry weights) were achieved at warmer night temperatures than day temperatures. similarly greater relative curd growth rate (rcgr) was recorded in plants grown at warmer night than day temperature (12/24°c) compared to the plants grown at cooler night than day temperature (24/12°c). moreover,rcgr decreased significantly (p<0.01) with increase in day temperature (dt) and increased significantly (p<0.01) with increase in night temperature (nt). similarly,curd length,diameter,fresh and dry weights decreased with increase in dt and increased with increase in nt. further,cauliflower stem length (sl) was linearly related to the effective mean temperature with optimum day temperature of 24°c and optimum night temperature of 12°c.