اثر فواصل آبیاری و ترکیبات ضدتعرق بر عملکرد، اجزای عملکرد و میزان روغن گیاه دارویی سیاهدانه (nigella sativa l.)

خشکی از جمله تنش های فیزیکی است که به‌عنوان عامل محدودکننده رشد گیاهان در بیشتر نقاط جهان شناخته شده است. به‌منظور ارزیابی اثر فواصل آبیاری و ترکیبات ضدتعرق بر عملکرد، اجزای عملکرد و میزان روغن سیاهدانه، تحقیقی در سال زراعی 1392- 1391 در دانشکده کشاورزی دانشگاه فردوسی مشهد در قالب آزمایش کرت های خرد شده با طرح پایه بلوک‌ های کامل تصادفی انجام شد. در کرت‌ های اصلی فواصل آبیاری (8 و 16 روز) و در کرت‌ های فرعی ترکیبات ضدتعرق کیتوزان (1، 5/0، 25/0 و صفر درصد)، موسیلاژ اسفرزه (5/1، 1، 5/0 و صفر درصد) و صمغ عربی (75/0، 5/0، 25/0‌ و صفر درصد) با سه تکرار قرار گرفتند. صفات اندازه گیری شده عبارت بودند از: عملکرد دانه، تعداد کپسول در بوته، تعداد دانه در کپسول، وزن دانه در بوته، وزن هزار دانه، تعداد دانه در بوته، شاخص برداشت و میزان روغن. نتایج حاصل از این پژوهش نشان داد که تیمار‌ های مختلف آبیاری و ترکیبات ضدتعرق تاثیر معنی داری بر تمامی صفات مورد مطالعه به‌جز وزن هزار دانه داشتند. افزایش فواصل آبیاری عملکرد، اجزای عملکرد و میزان روغن سیاهدانه را کاهش داد. ترکیبات ضدتعرق تاثیر معنی داری بر عملکرد، اجزای عملکرد و میزان روغن داشتند. در بین تیمار های مورد مطالعه، بیشترین عملکرد دانه (760 کیلوگرم در هکتار) و درصد روغن (05/27 درصد) و کمترین آن‌ها (419 کیلوگرم در هکتار و 57/23 درصد) به‌ترتیب در تیمار های ترکیب ضدتعرق کیتوزان 1 درصد با فاصله آبیاری هشت روز و تیمار صمغ عربی 25/0 درصد با فاصله آبیاری 16 روز حاصل شد.

effect of different irrigation intervals and anti-transpirants compounds on yield and yield components and oil of black cumin (nigella sativa l.)

introductionthe ever-increasing tendency to the use of medicinal plants in the world has grown concerns about their cultivation and production processes. as medicinal plants are more compatible with the nature, special interest and attention has recently been given to herb therapy, and use of medicinal plants, being limited by the rise of pharmaceutical drugs, has become again common and widespread due to a number of reasons. nigella sativa l. is one of the herbs that has a variety of uses and has been being used in iran’s traditional medicine since old times. today this plant is considered as one of the most important kinds of medicine. therefore, it is of great importance to conduct some researches on the herbs around the country due to different ecological requirements. n. sativa belonging to buttercup family, with the scientific name of ranunculaceae, is an annual, dicotyledonous, herbaceous plant. in several studies, n. sativa has been reported to have anti-oxidative, anti-inflammatory, strengthening of immune system, and anti-histamine and oil extract properties. furthermore, several effects such as lowering blood sugar, lipids, and hypertension, excretion of bile and uric acid, protection of liver, kidney and cardiovascular tissues as well as anti-seizure, anti-cancer, anti-microbial and anti-parasitic effects related to this plant have been reported. the aim of the present study is to improve the yield and yield components and oil of medicinal plant n. sativa by anti-transpiration compounds under drought stress conditions.                        materials and methodsan experiment was conducted at research station,faculty of agriculture, ferdowsi university of mashhad, in 2012-2013. the research was performed using a split plot experiment based on a randomized complete block design with three replications. the irrigation intervals (8 and 16 days) in main plots and anti-transpiration compounds of chitosan (0.25, 0.5 and 1%), plantogopsyllium mucilage (0.5, 1 and 1.5%) and arabic gum (0.25, 0.5 and 0.75 %) were put in subplots with three replications. also, the distance between the main plots in each block and distance between the two blocks were assigned as 100 cm and 200 cm, respectively; so that the moisture content of a plot had no effect on the adjacent plots. planting date was april16 and planting was performed by hand in 0.5cm-deep furrows. throughout the growing season, anti-transpiration compounds were applied concurrently with the imposition of drought stress, administered weekly at sunset until the flowering stage. subsequently, yield, yield components, and oil content were measured. results and discussion results showed that irrigation intervals had significant effects on all studied characteristics with the exception of 1000 seed weight. ncreasing irrigation intervals reduced percentage yield and yield components and oil of black cumin grains. anti-transpirants compounds did have significant effects on percentage of oil and yield and yield components of black cumin grains. there were significant difference between different anti-transpirants compounds in terms of oil and yield components yield and of black cumin grains. the 8 days irrigation interval produced more grain yield compared with 16 days irrigation intervals (621.56 vs. 484.23 kg/ha). the highest oil (27.74%) and lowest (21.74%), respectively, at treatment anti-transpirants compound chitosan1 percent with 8 days irrigation interval and gam arabic 0.25 percent was obtained with 16 days irrigation interval and chitosan stimulating abscisic acid synthesis in the treated plant would result in stomatal closure, reduction of stomatal conductance, transpiration rate and water content. they also pointed out that the anti-transpiration effect of chitosan was because of its stimulatory effect in increasing abscisic acid concentration in the treated leaves of bean plant. as the above compounds are natural and biodegradable, as well as safer and less expensive than other chemical anti-transpiration compounds, they can serve as a good alternative to the chemical compounds. cognition and expertise in water relations of plant and drought stress tolerance is considered as the main program in agriculture and the ability to withstand this stress is of great economic importance. conclusion the anti-transpiration compounds led to significant changes in terms of all the studied traits compared to the control, indicating the effectiveness of theses natural compounds. providing the appropriate conditions, 1% chitosan treatment can enhance the yield under drought stress. spraying by arabic gum did not improve the growth conditions. according to this experiment, 1% chitosan treatment and 1.5% plantago psyllium mucilage is considered the most appropriate strategy to enhance the yield of nigella sativa under drought stress.