The effect of ascorbic acid and sodium nitroprusside foliar application on seed yield, oil and some agronomical traits of safflower (Carthamus tinctorius L.) under water deficit stress

Drought stress is a major environmental constraint which inhibits the growth of plants and limits crop production. Nowadays, the application of antioxidants and plant growth regulators has discussed for decreasing the negative effect of different stresses. Ascorbic acid and sodium nitroprusside have substance caused witch the resistance to biotic and abiotic stresses. Nitric oxide (NO) is a relatively stable free radical gas which may act as a key signaling molecule in plants and mediates various physiological, pathophysiological and developmental processes and recently it has been suggested that it is involved in plant response to environmental stress. It was found to play a crucial role in plant growth and development, starting from germination to flowering, ripening of fruit and senescence of organs. Ascorbate is a major metabolite in plants. It is an antioxidant and, in association with other components of the antioxidant system, protects plants against oxidative damage resulting from aerobic metabolism, photosynthesis and a range of pollutants. Recent approaches, using mutants and transgenic plants, are providing evidence for a key role for the ascorbate–glutathione cycle in protecting plants against oxidative stress.To examin the effect of ascorbic acid and sodium nitroprusside foliar application on seed yield, oil and some traits of safflower (Carthamus tinctorius), a field experiment design was carried out in split plot factorial based on randomized complete block in shahrood university in 2011.
The experimental treatment included two levels of irrigation, including 8 days interval (well watered) and 16 days interval (water deficit stress) were in main plot, and foliar application of ascorbic acid in 3 levels (0, 10 and 20 mM) and sodium nitroprusside in 3 levels (0, 50 and 100 µM) were in sub plot. The experimental design was split plot factorial based on randomized complete block in 3 replication. Stress treatment applied after plants establishment completely. The foliar application of sodium nitroprusside and ascorbic acid were performed in 63 and 65 days after sowing respectively and then repeat after 1 week.
Results showed that relative water content (RWC(, seed coat weight and number of seed per capitol decreased by water deficit stress. Stress increased seed coat to kernel ratio significantly. Number of capitol per plant increased (2.5capitol per plant on average) by ascorbic acid foliar application in 10mM concentration, but RWC decreased in this concentration of ascorbic acid. 1000 seed weight, seed yield (13.2%), oil yield (17.2%) and oil percentage (4.6%) increased significantly by sodium nitroprusside (100 µM) foliar application.
20 mM Ascorbic acid and 100 mM sodium nitroprusside concentration can introduced as the best treatment compound and it seems that the foliar application of sodium nitroprusside with appropriate concentration can be helpful in reducing stress intensity. which suggests that the protective effect of SNP is exerted through NO release. The protective effects of NO in drought stress may be due to its ability to counteract reactive oxygen species (ROS) and reduce the oxidative damages.