Effect of the growth retardant chlormequat chloride (CCC) and different levels of nitrogen on some physiological and biochemical characteristics and yield of barley (Hordeum vulgare L.) cultivar makuyi

To study the effects of different concentrations of chlormequat chloride and different levels of nitrogen on some physiological and biochemical characteristics and yield of barley (Hordeum vulgare L.) cultivar makuyi a factorial randomized complete block design was used with 4 replications in spring 2015. Treatments included chlormequat chloride concentrations (0, 500, 1,000, and 1500 mg/ha) and nitrogen at 3 levels (50, 100, and 150 kg/ha). Results suggest a significant difference between interaction effects of chlormequat chloride and nitrogen fertilizer on chlorophyll content, relative water content, yield and protein percentage, and activity of superoxide dismutase and catalase enzymes at 1% probability level and in the number of seeds per spike, 1000 seed weight, and glutathione peroxidase enzyme activity at 5% probability level. An increase in the consumption of nitrogen fertilizer decreased the relative water content of leaves due to reduced leaf water potential. Chlormequat chloride by transferring sufficient photosynthetic material to the seeds played an important role in their filling and increased seed weight. Also, the activities of superoxide dismutase, catalase, and glutathione peroxidase enzymes were decreased by increasing the consumption of chlormequat chloride concentration and nitrogen uptake. In general, through applying 1500 mg/ha chlormequat chloride and 150 kg/ha nitrogen, the highest chlorophyll content, relative water content, yield components, yield, and protein percent were obtained.