ارزیابی صفات بیوشیمیایی و زراعی ارقام کنجد تحت اثر کاربرد نانو کود فسفر و کیتوزان در شرایط قطع آبیاری

به منظور بررسی اثر قطع آبیاری و محلول‌پاشی با کیتوزان و نانوکود فسفر بر عملکرد و اجزای عملکرد و کیفیت دانه ارقام کنجد بعد از کشت گندم، آزمایشی به صورت اسپلیت‌پلات فاکتوریل در سه تکرار در مزرعه پژوهشی دانشگاه شاهد تهران در سال‌های زراعی 95-1394 و 96-1395 انجام شد. عوامل آزمایش شامل قطع آبیاری در سه سطح براساس مراحل فنولوژیکی، عدم تنش (آبیاری نرمال)، قطع آبیاری در 50 درصد دانه‌بندی و گلدهی در کرت‌های اصلی و محلول‌پاشی در چهار سطح شامل عدم محلول‌پاشی، نانو کلات فسفر (دو در هزار)، کیتوزان (سه در هزار) و ترکیب نانو کلات فسفر+کیتوزان و دو رقم اولتان و ناز تک شاخه کنجد در کرت‌های فرعی بودند. نتایج نشان داد بیشترین وزن هزار دانه در سال اول آزمایش و رقم اولتان (3.10 گرم) به دست آمد. بیشترین عملکرد دانه در سال دوم، تحت شرایط بدون تنش و تنش متوسط و محلول‌پاشی با نانو کلات فسفر به‌تنهایی یا در ترکیب کیتوزان (به ترتیب 2821.8، 2572.4، 2808.4 و 2904.5 کیلوگرم در هکتار) مشاهده شد. به‌طور کلی در بین سطوح مختلف تنش خشکی، تنش شدید (آبیاری تا 50 درصد گلدهی) منجر به کاهش معنادار میانگین عملکرد دانه (بیش از 50 درصد) گردید، ولی تنش خشکی متوسط (آبیاری تا 50 درصد دانه‌بندی) به‌خصوص در شرایط استفاده از ترکیبات کیتوزان و نانو کود فسفر دارای بالاترین عملکرد دانه (5/2904 کیلوگرم در هکتار) بود. درصد روغن دانه در سال دوم تحت شرایط عدم تنش دارای بالاترین میانگین (57.02 درصد) بود. در مقایسه بین دو رقم، بیشترین و کمترین عملکرد روغن به ترتیب در رقم ناز و اولتان (858.4 و 731.7 کیلوگرم در هکتار) مشاهده شد. میزان اسیدهای چرب اشباع (پالمیتیک و استئاریک) در تیمار عدم محلولپاشی در رقم اولتان دارای بالاترین میانگین (به ترتیب 12.5 و 9.3) و برعکس، کمترین محتوای اسید چرب لینولئیک (24.88 درصد) در این تیمار مشاهده شد. به‌طورکلی استفاده از نانو کود فسفر به همراه کیتوزان باعث افزایش کمی و کیفی عملکرد دانه کنجد گردید و منجر به افزایش شاخص­های رشدی و کیفی در شرایط تنش خشکی شد.

Evaluation of biochemical and agronomic traits of sesame cultivars under application of phosphorus nanochelate and chitosan fertilizers under irrigation cutoff

Introduction Drought is a major environmental stress affecting plant morphology, physiology, and biochemistry. Two management strategies for controlling drought stress include the use of nutrients and planting resistant plants. Chitosan, known as elicitors, is considered a natural biopolymer modified from chitin, which is the main structural component of squid pens, cell walls of some fungi and crab shells. Nanotechnology provides a new interdisciplinary venture into agriculture and food sciences by converging science and engineering. In addition, nanoparticles have potential applications in agriculture system, viz., the pollutants detection, plant diseases, pests, and pathogens, controlled delivery of pesticide, fertilizers, nutrients, and genetic material, and can act as nano architects in forming and binding soil structure. Sesame (Sesamum indicum L.) is a source of excellent vegetable oil (3563%). Sesame is considered as drought tolerant crop, the productivity is heavily affected by severe drought stress mainly when it occurs during anthesis. Restricted water resources are considered as a limiting factor for irrigation applications around the world. Therefore, the present study aimed to evaluate the changes in the quality and yield traits of two sesame genotypes under drought stress and foliar application of chitosan and phosphorus nanochelate in second cultivation. Material and methods The present study was conducted to investigate the changes in the quality and yield traits related to two sesame genotypes under irrigation cutoff and foliar application of chitosan and phosphorus nanochelate in the second cultivation at research field of Shahed University in Tehran, Iran, during 201516 and 201617. The experiment was conducted during a twoyear factorial split plot experiment based on completely randomized block design with three replications. The research farm is located at geographical characteristics of latitude 31° and 36’ and longitude 48° and 53’ and the height of this area from sea level is equal to 1050 m. The experimental factors including irrigation treatments at normal irrigation as control (nonstress), mild stress (irrigation cutoff at 50% seed ripping) and severe stress (irrigation cutoff at 50% flowering) were in the main plots and spraying treatments including nonspraying (control), phosphorus nanochelate (2 ppt), chitosan (3 g.L1), and the combination of phosphorus nanochelate + chitosan and Oltan, and Naz single branch sesame cultivars were in the subplots. Number of capsules per plant, number of grain per plant, 1000grain weight, grain yield, biological yield, oil percentage and yield, and fatty acids composition (oleic, linoleic, palmitic, and stearic contents) was investigated. Result and discussion The results showed that the highest 1000grain weight was obtained in the first year of experiment and Oltan genotype (3.10 g) and the lowest mean was in the first year in Naz single branch genotype (2.51 g). The highest grain yield was observed in the second year of the experiment under without stress and mild stress conditions (irrigation up to seed ripening) and foliar application of phosphorus nanochelate alone or combined with chitosan. In general, between different levels of irrigation treatments, severe stress (irrigation up flowering) resulted in a significant reduction in the grain yield, but mild drought stress (irrigation up to seed ripening), especially in terms of using chitosan and nanofertilizer compounds, had a good grain yield. In the interactions effects of the year in drought stress, the highest seed oil percentage was obtained in the nondrought stress (normal irrigation) during the second year of the experiment (57.02%) and the lowest mean of this trait was observed in the second year under severe drought stress condition. Compared to the two cultivars, the highest oil yield was in Naz single branch cultivar (858.4 kg/ha) and the lowest mean of Oltan cultivar (731.7 kg/ha) was observed. The highest amount of saturated fatty acids (palmitic and stearic) was achieved in Oltan cultivar under nonfoliar aplication. In contrast, the lowest content of linoleic fatty acid (unsaturated fatty acid) was observed in this treatment. In general, the application of phosphorus nanochelate with chitosan increased the quantitative and qualitative characteristics of sesame seed yield and resulted in increased growth and quality growth factors in drought stress conditions. Summer planting of sesame plant is recommended in warm and dry climatic conditions (with end session drought stress) along with chitosan and phosphorus nano fertilizer.Conclusion Based on the aim of this research, the results showed that planting both Oltan and Naz single branch cultivars in the south Tehran climatic after wheat harvesting (as the second crop) had favorable results for grain and oil yield. In general, the results showed that coapplication of phosphorus nanochelate and chitosan fertilizers under mild drought stress (irrigation up to seed ripening) resulted in the moderate negative effect of drought stress and produced grain and oil yield. Also, the cultivation of this plant in warm and dry climates (similar to southern Tehran) under the mentioned conditions (coapplication of phosphorus nanochelate and chitosan fertilizers) is recommended under limited irrigation conditions (end of season drought stress).