نوع مقاله : مقاله پژوهشی
نویسندگان
چکیده
در زمینة سازگاری با کمآبی، راهکارهای مختلفی قابل پیشنهاد و اجرا ست که از آن جمله میتوان به اتخاذ سیاستهای مناسب، برای بهینهسازی مصرف آب، از طریق تعیین توابع بهینه تولید اشاره کرد. کمآبی و کاهش کیفیت منابع آب و خاک در کشور، از عوامل اصلی کاهش تولید است؛ از این رو، این تحقیق برای تعیین ضرایب حساسیت گیاه و تابع بهینه تولید آب- شوری- عملکرد برای شلغم، در کاشمر اجرا شد. آزمایش فاکتوریل در قالب طرح کاملاً تصادفی با سه تکرار شامل دو فاکتور شوری و آب آبیاری اعمال شد. چهار سطح شوری آب آبیاری شامل (آب شرب) 0.7= S1، 4= S2، 8= S3 و 12= S4 دسی‌زیمنس بر متر و سه سطح آب آبیاری شامل آبیاری کامل (100% نیاز آبی)= W1، W1 75%= W2 و W1 50%= W3 بود که در یک خاک با بافت لومی شنی اعمال شدند. دادههای عملکرد بر فرمهای مختلف توابع تولید (خطی ساده، خطی لگاریتمی، درجه دوم و نمایی) برازش داده و پس از آنالیز حساسیت، تابع بهینه تولید شلغم تعیین شد. سپس مقادیر کارآیی مصرف آب و ضرایب حساسیت گیاه تعیین شد. نتایج آنالیز حساسیت نشان داد که تابع تولید درجة دوم برای شلغم به‌عنوان تابع بهینة تولید، قابل توصیه است. بررسی مقادیر حداکثر خطا (ME) نشان داد که بیشترین خطا مربوط به توابع لگاریتمی و خطی ساده میباشد. تیمار شاهد (W1S1) و تیمار W2S1 (75% نیاز آبی) به‌ترتیب با 6.66 و7.42 کیلوگرم بر مترمکعب پربازدهترین سطوح آبیاری هستند؛ اما با افزایش تنش خشکی و شوری بهرهوری آب کاهش یافت. مقدار متوسط ضریب Ky در وضعیت تنش توأمان شوری و خشکی برابر با 1.731 محاسبه شد. همچنین ضریب حساسیت گیاه (Ks) با افزایش تنش شوری و خشکی کاهش یافت که کمترین مقدار آن (0.5) مربوط به تیمار W3S4 است. منحنیهای هم محصول نشان میدهند که با افزایش میزان آبیاری، میتوان از آب آبیاری با شوری بالاتری در آبیاری شلغم استفاده کرد؛ به گونهای که عملکرد نیز تغییر نکند.
کلیدواژه‌ها
عنوان مقاله [English]
Determination of the yield response factor to water (Ky) and the best function of water-salinity-yield of turnip in Kashmar
نویسندگان [English]
- mehdi mokari
- Meysam Abedinpour
- Hadi Dehghan
چکیده [English]
Water shortage and drought are two phenomena that are unavoidable due to the high variations in soil moisture in time and place during the entire growing season. Generally, the irrigation water depth varies under different conditions of land shortage, drought and salinity stress, or a combination of these conditions. When irrigation with this depth can be maximized, net income can be maximized. In order to determine the optimum depth, various tools such as the production function of the yield, irrigation water and its derivatives, initial and current costs, yield prices and information on the water and land are needed. The turnip (Brassica rapa L.), as a strong source of nutritional supplementation, contains a variety of antioxidants such as vitamins and schucosinolates (Norin et al., 2010). Turnips are used in fresh and dried forms for human feed.
Since there has been no research in the field of determining the optimal production function of water-salinity-turnip yield in the country, the aim of this study is to find the optimal function of turnip production in combination with salinity and drought so that the water consumption can be minimized by using saline water.
This experiment was conducted as a factorial based on completely randomized design with three replications including two factors of salinity and irrigation water. Four levels of irrigation water salinity including two factors of salinity and irrigation water were applied, with three replications. The four levels of saline irrigation water include: S1: 0.7 (as a control), S2: 4, S3: 8 and S4: 12 ds/m and three irrigation water levels were considered as W1: 100% of crop water requirement, W2: 75% of W1, and W3: 50%W1.
The statistical data of the performance of the project implementation were fitted with the SPSS software and various forms of production functions were determined. For this purpose, the optimal production function, a statistical sensitivity analysis, was performed and then the relevant statistics determined the role of each entity in generating functions quantitatively. To evaluate the validity of the obtained functions, the analysis of the remaining errors and the differences between the measurement and prediction values were used. The statistics required for this study were the maximum error (ME), root means square error (RMSE), the coefficient of determination (R2), modelling efficiency (EF), and residual coefficient of variation (CRM).
The results showed that the highest yield was obtained in control treatment (W1S1) and 75% W1 (W2S1) treatments at the rate of 6.66 and 7.42 kg/m3, respectively. In addition, by increasing the drought and salinity stress, the water use efficiency decreased. The Ky values at the same conditions of salinity and drought stress were more than Ky in drought stress and less than Ky in salinity stress conditions. Therefore, it can be concluded that the effect of salinity stress on reducing yield is more than drought stress. Subsequently, Ks values showed that by increasing salinity and drought stress, the crop evapotranspiration was decreased. In order to adapt to the water shortage, it can use the optimal production function for the turnip yield in Kashmar.
It can be stated that in drought stress conditions, evaporation and transpiration reduction is due to the water deficiency, and in salt stress conditions is due to the decreased water absorption because of decreasing osmotic potential of root zone. The results of the product curves showed that by increasing the amount of irrigation water, the water with higher salinity can be used.
کلیدواژه‌ها [English]
- drought stress
- Evapotranspiration
- Turnip
- Water use efficiency
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