Effect of chitosan and nano-chitosan on agronomic properties and omega-3, 6 and 9 fatty acids in some cultivars of Nigella sativa L. under drought stresscondition

Water stress is one of the limiting factors of plant growth. In order to investigate the effect of chitosan and nano-chitosan on Nigella sativa L. under drought stress, a split plot experiment based on randomized complete block design was conducted in research Field of Islamic Azad University Arak Branch in 2016. The main plots consisted of spraying with chitosan, nano-chitosan and water as control and the sub plots consisted of cultivars Arak, Azerbaijan, Semirom, Yasuj and Torbat-e-Heydariyeh. Irrigation was performed regularly from the beginning of planting until flowering stage and then stopped and spraying was achieved. After 80% emergence of floret, plots were sampled and number of secondary branches, capsules per plant, plant height, 1000 seed weight and oil percentage were evaluated. Percentages of oil and fatty acids were measured by gas chromatography.Experimental results were showed that drought stress reduced the components of black cumin yield but improved qualitative factors such as oil and fatty acids percentage. The highest and lowest seed oil content was in Azarbaijan (28.76%) and Semirom (26.39%), respectively. Yasuj can be considered as a drought tolerant cultivar due to its high content of capsules, 1000-grain weight and weight/m2. The effect of nano-chitosan in moderating stress-induced effects was better than chitosan. Azerbaijan and Semirom cultivars had the highest amount of oleic acid (Omega 9), Yasuj cultivar had the highest amount of linoleic acid (Omega 6) and Torbat Heydariyeh and Arak cultivars had the highest amount of linoleic acid (Omega 3).