تاثیر محلول‌پاشی سالیسیلیک اسید بر کارآیی مصرف آب در جو در شرایط قطع آبیاری

به منظور بررسی تاثیر سالیسیلیک اسید بر کارآیی مصرف آب و برخی خصوصیات فیزیولوژیکی جو در شرایط تنش خشکی، آزمایشی در سال زراعی 1396 به صورت فاکتوریل در قالب طرح پایه بلوک‌های کامل تصادفی با سه تکرار در مزارع کیذور واقع در شهرستان سبزوار انجام شد. تیمارها شامل آبیاری در دو سطح قطع آبیاری (قطع آبیاری از مرحله آبستنی (کد 49 زادوکس) تا برداشت) و آبیاری کامل و تیمار محلول‌پاشی سالیسیلیک اسید در چهار سطح صفر (شاهد)، دو، چهار و شش میلی‌مولار در مرحله ساقه‌دهی (کد 39 زادوکس) روی جو اجرا شد. نتایج نشان داد که در هر دو شرایط آبیاری کامل و قطع آبیاری بیشترین تعداد سنبله، تعداد دانه در سنبله، عملکرد دانه و عملکرد بیولوژیکی در متر مربع به‌ترتیب در تیمار محلول‌پاشی دو تا شش میلی‌مولار سالسیلیک اسید و کمترین آن مربوط به تیمار شاهد بود. کمترین کارایی مصرف آب (0.38) در شرایط قطع آبیاری و بدون مصرف سالیسیلیک اسید حاصل شد و با مصرف سالیسیلیک اسید تا شش میلی‌مولار کارایی مصرف آب افزایش یافت. همچنین با افزایش مصرف سالیسیلیک اسید در شرایط قطع آبیاری در مقایسه با آبیاری کامل، کارایی مصرف آب افزایش بیشتری یافت. کمبود آب از یک طرف با تاثیر بر ساختار غشای سلول سبب افزایش نفوذپذیری غشا نسبت به یون‌ها و ماکرو مولکول‌ها شد (نشت الکترولیت برگ در شرایط آبیاری کامل و قطع آبیاری به‎ترتیب 0.45 و 0.58 بود) و از طرف دیگر، با افت شاخص کلروفیل، فتوسنتز را کاهش داد که در نهایت کاهش عملکرد و اجزای آن را به همراه داشت. از طرفی، اسید سالیسیلیک موجب تعدیل تنش خشکی از طریق کاهش نشت یونی (عدم مصرف و مصرف سالسیلیک اسید شش میلی‌مولار در شرایط قطع آبیاری به‌‎ترتیب 0.61 و 0.38 بود)، افزایش غلظت پرولین و شاخص کلروفیل در نتیجه بهبود عملکرد دانه گندم در شرایط قطع آبیاری در مقایسه با آبیاری کامل گردید.

Effect of Salicylic Acid Foliar Application on Barley Water use Efficiency in CutOff Condition

<p class= "8TEXTAbstract " style= "textalign: justify; textjustify: kashida; textkashida: 0%; direction: ltr; unicodebidi: embed; " > <strong >Introduction: </strong >Drought stress has osmotic and physiological effects on plants, resulting in reduced growth, metabolic disorders and oxidative stress in plants. Different plants use several strategies to cope with drought stress. External application of different compounds such as organic solvents and minerals is a solution to increase drought tolerance in plants. Salicylic acid is recognized as a plant hormone and its role in defense mechanisms against biological and nonbiological stressors is well defined. The purpose of this experiment was to evaluate the effect of salicylic acid on reducing the effects of drought stress on yield, water use efficiency and some physiological characteristics of the barely. </p >; <p class= "8TEXTAbstract " style= "textalign: justify; textjustify: kashida; textkashida: 0%; direction: ltr; unicodebidi: embed; " > <strong >Materials and Methods: </strong >This experiment was carried out as factorial experiment based on randomized complete block design with three replications in the Kizor fields located in the city of Sabzevar in 2017. The altitude of this area is 1195 m above sea level and is 36° 5 N latitude and 44° 3 ' E longitude. The treatments included irrigation at two levels of cutoff irrigation (irrigation cut from booting to harvesting stage) (Z39) and noncutoff irrigation and salicylic acid spraying treatment at four levels of zero (control), two, four and six mM at stage of shoots on barley. Data were analyzed with the SAS software ver 9.1 and the means were compared with LSD test. </p >; <p class= "8TEXTAbstract " style= "textalign: justify; textjustify: kashida; textkashida: 0%; direction: ltr; unicodebidi: embed; " > <strong >Results and Discussion: </strong >The results showed that in both conditions of noncutoff irrigation and cutoff irrigation, the highest number of spikes, number of seeds, seed yield and biological yield per m <sup >2 </sup > were obtained in two to six mM of salicylic acid, respectively, and the lowest was related to control treatment. The lowest water use efficiency (0.38) was obtained under noncutoff irrigation conditions without salicylic acid and with the consumption of salicylic acid up to six mM, water use efficiency increased. Also, salicylic acid spraying in cutoff irrigation conditions compared to noncutoff irrigation led to increase water use efficiency. In both conditions, noncutoff irrigation and cutoff irrigation, the highest and lowest grain yields were obtained from 6 mM salicylic acid and control treatments (without salicylic acid spraying), respectively. Under noncutoff irrigation and cutoff irrigation, spraying with 6 mM of salicylic acid increased the grain yield by 44% and 48% compared to control (without salicylic acid spraying). It seems that the effect of salicylic acid spraying in cutoff irrigation conditions was more effective than noncutoff irrigation conditions. The cause of higher water use efficiency in cutoff irrigation conditions in comparison with noncutoff irrigation was high waste of water due to evapotranspiration and deep penetration in noncutoff irrigation treatments. Spraying with salicylic acid by stimulating the growth of hair and subroots plays an effective role in increasing water use efficiency. In cutoff irrigation conditions, salicylic acid consumption has reduced the amount of electrolyte leakage so that the spray at a concentration of 6 mM of salicylic acid compared to the control (without salicylic acid spraying) decreased electrolyte leakage about 38 %. The reduction of membrane damage due to the use of salicylic acid is related to the production of antioxidants. Spraying with salicylic acid increases the stability of the membrane against oxidative stresses. </p >; <p class= "8TEXTAbstract " style= "textalign: justify; textjustify: kashida; textkashida: 0%; direction: ltr; unicodebidi: embed; " > <strong >Conclusions: </strong >Water deficit at first affecting the structure of the cell membrane, increased the permeability of the membrane relative to the ions and macromolecules and at second stage decreased the photosynthesis by decreasing the chlorophyll index, which finally reduced the yield and its components. Also, salicylic acid alleviate drought stress by reducing ion leakage, increasing proline concentration and chlorophyll index resulting to improved wheat grain yield under cutoff irrigation conditions compared to noncutoff irrigation. </p >