اثر مالچ پلی اتیلن شفاف بر تولید و کارآیی مصرف آب در کدوی تخم کاغذی (Cucurbita Pepo) تحت سطوح مختلف رطوبتی

منابع آب برای تولید محصولات کشاورزی بسیار محدود است. بنابراین استفادۀ بهینه از منابع آبی موجود و افزایش کارایی مصرف آب در بخش کشاورزی ضروری است. هدف از اجرای این تحقیق تعیین اثر مالچ پلی اتیلن شفاف بر عملکرد و کارایی مصرف آب در کدوی تخم کاغذی بود. آزمایش با چهار تیمار در قالب طرح بلوک های کامل تصادفی با سه تکرار در سال زراعی 1395 در بخش مرکزی شهرستان اصفهان منطقۀ براآن شمالی با عرض جغرافیایی 32 درجه و 32 دقیقه شمالی و طول جغرافیایی 51 درجه و 52 دقیقه شرقی و ارتفاع 1534 متر از سطح دریا انجام شد. تیمارهای آزمایش شامل آبیاری کامل+ مالچ پلاستیک (m+fw)، 75% آبیاری کامل+ مالچ پلاستیک (m+0.75fw)، 50% آبیاری کامل+ مالچ پلاستیک (m+0.5fw)، و آبیاری کامل بدون مالچ (fw) بودند. نتایج نشان داد که اثر سطوح مختلف رطوبتی و مالچ بر تعداد میوه در بوته، متوسط وزن میوه، عملکرد میوه، تعداد دانه در میوه، قطر میوه، وزن هزار دانه، عملکرد دانه، کارایی مصرف آب، میزان روغن و عملکرد روغن معنی‎دار بود. بیشترین و کمترین میزان تعداد میوه در بوته، متوسط وزن میوه، عملکرد میوه، وزن هزار دانه، عملکرد دانه، عملکرد روغن و درصد روغن به ترتیب به تیمارهای m+fw و m+0.5fw اختصاص داشت. تیمار m+0.75fw در اکثر صفات مورد بررسی، تفاوت آماری معنی داری با fw نداشت ولی کارایی مصرف آب آن بطور معنی‎داری بیشتر از fw بود. بنابراین، استفاده از مالچ پلاستکی در شرایط بدون محدودیت آب موجب افزایش عملکرد و در شرایط دسترسی کمتر به آب علاوه بر جلوگیری از کاهش عملکرد جهت صرفه جویی در مصرف آب در مناطق گرم و خشک کشور و افزایش کارایی مصرف آب اهمیت دارد.

Effect of Transparent Poly Ethylene Mulch on Production and Water Use Efficiency of HullLess Seed Pumpkin (Cucurbita pepo L.) under Different Levels of Moisture

Introduction: Water resources are very limited for agricultural production. Therefore, optimal use of available water resources and increased water use efficiency in agriculture are necessary. Application of poly ethylene mulch is one of the approaches that can be effective in increasing water use efficiency. The water deficient trend is increasing in agricultural lands of the Iran and, on the other hand, the yield components of hullless seed pumpkin are sensitive to drought stress. Therefore, the aim of this study was to determine the effect of transparent polyethylene mulch on the performance and water use efficiency of hullless seed pumpkin under different irrigation rates.Materials and Methods: This experiment was carried out in the central part of Isfahan, Northern Baraan (320 and 32/N, 510 and 52/ E, and 1534 m above sea level) in a randomized complete block design with three replications, during 2016. Treatments consisted of full irrigation+ poly ethylene mulch (M+FW), 0.75% full irrigation+ poly ethylene mulch (M+0.75FW), 0.50% full irrigation+ poly ethylene mulch (M+0.5 FW), and full irrigation without mulch (FW). In April, the cultivation operations include mechanical planting, mulch were done. The spacing of the rows was 150 cm and the spacing between plants was 70 cm. The irrigation was applied until the plant was fully established and then drought stress was begun based on above irrigation treatments. The studied traits were number of fruits per plant, average fruit weight (kg), fruit yield (ton ha1), number of seeds per fruit, fruit diameter (cm), 1000 grains weight (g), grain yield (kg ha1), water use efficiency (kg m3), oil content (%) and oil yield (kg ha1). Statistical analysis was performed using SAS software and comparisons of the means were made using the least significant difference (LSD) test at the 5% probability level.Results and Discussion: The highest number of fruits per plant belonged to M+FW treatment (with an average of 3.22) and the lowest was recorded in M+0.5FW treatment (with an average of 2.44). This difference between treatment FW and M+0.75FW can be due to the high moisture under the poly ethylene mulch. The highest fruit weight (3.60 kg) was obtained in M+FW treatments, which had a significant difference with other treatments. The difference weight of fruit in M + FW treatment was 14% compared to FW irrigation treatments. The highest fruit yield (95.72 ton ha1) belonged to M+FW treatment and the lowest one (79.78) belonged to M+0.5FW treatment. The difference in fruit yield in M+0.75FW compared to FW treatment was 6%, but it was not significant. The number of seeds per fruit in M+0.75FW compared to FW and M+0.5FW treatments showed a difference of 13% and 17%, respectively which they were significant only with M+0.5FW treatment. With increasing drought stress, the amount of photosynthetic assimilate decreased, which reduced the number of seeds per fruit. The highest 1000 grains weight (173.13 g) belonged to M+FW treatment and the lowest one belonged to M+0.5FW (156.18 g). 1000 seeds weight in FW treatment was not significant compared to M+0.75FW treatment. Drought stress during plant development decreased the leaf area index in the plant. Application of plastic mulch reduces the effect of drought stress on leaf growth and its photosynthesis by decreasing water loss by evapotranspiration and transpiration. The difference grain yield between two treatments M+0.75FW with FW was 7% and this difference was not significant. Only significant difference was observed among M+0.5FW treatment with other treatments. The effect of different levels of moisture on water use efficiency was significant at 1% probability level. The highest water use efficiency was recorded in M+0.5FW treatment and the lowest was recorded in FW treatment. The difference in water use efficiency between M+0.75FW with full irrigation (FW) was 0.99 kg m3, which was significant. Difference in water use efficiency between M+FW and FW was not significant for water use efficiency. The use of plastic mulch reduced water loss throughout the plant growth period and significantly increased water use efficiency. There was a significant difference among M+FW, M+0.75FW and FW for oil content. The highest and lowest oil contents belonged to M+FW and M+0.5FW, respectively. The maximum oil yield (558 kg ha1) belonged to M+FW and the lowest one (412 kg ha1) was obtained in M+0.5FW. Conclusion: Transparent plastic mulch under water stress conditions can reduce the effect of drought stress on hullless seed pumpkin by preserving water and other beneficial effects, including weeds reduction. Therefore, the use of this type of mulch is recommended for the cultivation of hullless seed pumpkin in the central areas of the country facing the water crisis.