Comparative effects of cold air and cold water stress on chlorophyll parameters in rice (Oryza sativa L.)

This experiment aimed to determine the effects of cold stress on the leaf area and chlorophyll content of four rice (Oryza cultivar L.) cultivars. A completely randomized design in a factorial arrangement with three replicates was used. The treatments were three levels of cold stress (control, cold air and cold water) and four rice genotypes (consisted of Shiroodi, Shafagh, Khazar and Fajr). Results indicated that there was a significant effect on the shoot fresh weight, leaf area, chlorophyll a, b, a+b, a/b and carotenoid due to the main effects of genotype (G) and cold stress (C) as well as interaction of G×C. The results clearly indicated that chlorophyll content in rice cultivars tended to decrease when cold water and air stresses were applied. However, low levels of air or water temperature had a little effect on chlorophyll content in Fajr cultivar. In both stress conditions, carotenoid contents of rice leaves in all cultivars increased. Maximum increased was recorded in Fajr, followed by Khazar, Shafagh and Shiroodi cultivars.