تاثیر محلول‌پاشی برگی سیلیسیم‌دی اکسید نانو و غیر نانو بر عملکرد و توزیع مجدد ماده خشک گندم در شرایط تنش خشکی

به‌منظور بررسی تاثیر محلول‌پاشی سیلیسیم بر عملکرد و توزیع مجدد ماده خشک گندم در شرایط تنش خشکی، پژوهشی مزرعه‌ای در سال زراعی 95-1394 به‌صورت کرت‌های خردشده در قالب طرح پایه بلوک‌های کامل تصادفی در چهار تکرار در دانشگاه علوم کشاورزی و منابع طبیعی رامین خوزستان اجرا گردید. تیمار تنش خشکی شامل سه سطح آبیاری نرمال (بدون قطع آبیاری یا شاهد)، تنش خشکی از زمان ساقه‌روی تا گل‌دهی و تنش خشکی از گل‌دهی تا رسیدگی دانه به عنوان فاکتور اصلی و محلول‌پاشی سطوح دی‌اکسید سیلیسیم در هفت سطح شامل بدون سیلیسیم (شاهد)، کاربرد ذرات نانو و غیرنانو سیلیسیم در غلظت‌های 50، 100 و 150 میلی‌گرم در لیتر به‌عنوان فاکتور فرعی در نظر گرفته شدند. نتایج نشان داد که تنش خشکی در دوره ساقه‌روی تا گل‌دهی عملکرد دانه گندم نسبت به شرایط آبیاری معمول را در حدود 35 درصد کاهش داد. محلول‌پاشی سیلیسیم تا حدودی تاثیر منفی تنش خشکی بر عملکرد دانه را تقلیل داد. عملکرد دانه گندم با کاربرد غلظت 100 میلی‌گرم در لیتر سیلیسیم نانو (577.61 گرم در متر مربع) و 150 میلی‌گرم در لیتر سیلیسیم غیر نانو (527.73 گرم در متر مربع) به‌طور معنی‌داری بیشتر از سایر تیمارهای محلول‌پاشی شد. صرف نظر از تیمارهای محلول‌پاشی، توزیع مجدد ماده خشک در شرایط آبیاری معمول در حدود 11 درصد کمتر از شرایط تنش خشکی بود. بیشترین سهم توزیع مجدد از عملکرد دانه گندم مربوط به محلول‌پاشی با غلظت 100 میلی‌گرم در لیتر سیلیسیم نانو در شرایط تنش از گلدهی تا پایان دوره رشد بود. همچنین تنش خشکی سهم فتوسنتز جاری در پر کردن دانه‌ها را به‌طور معنی‌داری کاهش داد.

The effect of foliar application of nano and bulk silicon dioxide particles on grain yield and redistribution of dry matter in wheat under drought stress

Introduction Under water shortage, applying and adjusting of some elements concentration such assilicon (Si) can be used as a strategy to reducethe negative effects of stress on wheat(Triticum aestivum L.) growth and enhanced plant compatibility.Some of the studies showed that exogenousSi application increased crop resistance to environmental stresses such as drought (Ahmed et al., 2011; Maghsoudi and Emam, 2016). Likewise, macro and micro nano fertilizers application caused an increase in crop yield. Therefore, this study aimed to investigate the effect of foliar application of nano and bulk Si dioxide particles on yield and yield components of wheat and also to determine the contribution of different sources in grain yield formation. Materials and methods In order to investigate the effect of foliar application of silicon on yield and redistribution of wheat dry matter under drought stress conditions, a field experiment was conducted as split plots based on a randomized complete block design with four replications at Ramin Agriculture and Natural Resources University of Khuzestan. Drought stress periods included three levels of normal irrigation (full irrigation throughout growing season or control), drought stress from stem elongation to flowering and drought stress from flowering to maturity were considered as main plot and foliar application of silicon dioxide levels in seven levels including nonfoliar application (control), application of nano and bulk particles of silicon dioxide in concentrations of 50, 100 and 150 mg L1 were considered as subplots. Data analysis was performed using SAS software and GLM procedure, and means comparison was carried out using a protected LSD method at a 5% probability level. Results and discussion Drought stress from stem elongation to flowering reduced the number of fertile tillers, number of spikelets per spike and number of seeds per spike, thereby reducing seed yield by about 35% compared to full irrigation conditions. Drought stress in the grain filling period resulted in a 10% reduction in wheat 1000grains weight. Silica foliar application slightly reduced the effect of drought stress on grain yield.Wheat grain yield was significantly higher than other spraying treatments with the application of concentration of 100 mg L1 of nano silicon particles (61.71 g m2) and 150 mg L1 of bulk silicon particles (572.73 g m2). The efficiency of redistribution of dry matter in drought stress conditions from stem elongation to flowering (18.46%) was significantly higher than non stress conditions (14.07%) or stress induced from flowering stage to end of growth period (13.75%) Regardless of Silica foliar application treatments, redistribution of dry matter under full irrigation conditions was about 11% less than that of drought stress. The highest percentage of redistribution of dry matter from wheat grain yield was related to foliar application with concentration of 100 mg L1 of bulk silicon particles under drought stress from flowering to the end of the growth period. The contribution of current photosynthesis in grain filling in nonstress conditions (458.68 g m2) was significantly higher than drought stress conditions from flowering stage to end of growth period (399.68 g m2) and for this was also significantly more than that of the stress conditions from the stem elongation to flowering (261.98 g m2). The contribution of current photosynthesis in grain filling in spray treatment with a concentration of 100 mg L1 of nano silicon dioxide was the maximum (451.25 g m2) and in control treatment was at least (311.11 g m2). It seems that nano silicon particles application caused an increase in plant tolerance to drought stress due toincreasing water balance, photosynthetic efficiency, and seedling growth (Hattori et al., 2005). Conclusion In general, the present study showed that the presence of silicon and especially nano particles in drought stress has a significant role in improving yield and grain yield components of wheat as well as redistribution of dry matter. It seems that in order to reduce the negative effect of moisture stress during wheat growth season and increase grain yield and dry matter redistribution, application of 100 mg L1of nanosilica particles is recommended.