تاثیر سطوح مختلف کیفیت آب آبیاری و کود سولفات آهن بر عملکرد و اجزای عملکرد گندم (.Triticum Aestivum L)

به منظور مطالعه تاثیر کیفیت آب آبیاری و مصرف خاکی سولفات آهن بر عملکرد و اجزای عملکرد گندم (رقم بم) آزمایشی در ایستگاه تحقیقاتی مرکز ملی تحقیقات شوری اجرا شد. این تحقیق دارای سه سطح کیفیت آب آبیاری (شوری 1.88 دسی‌زیمنس بر متر و نسبت جذب سدیم 5.76، شوری 7.22 دسی‌زیمنس بر متر و نسبت جذب سدیم 11.82، و شوری 14.16 دسی زیمنس برمتر و نسبت جذب سدیم 24.73) به عنوان فاکتور اصلی و چهار سطح کود سولفات آهن شامل صفر، 20، 40 و 80 کیلوگرم در هکتار به عنوان فاکتور فرعی بود. آزمایش در قالب طرح آماری بلوک‌های کامل تصادفی به صورت اسپلیت پلات با سه تکرار اجرا شد. نتایج نشان داد که با افزایش شوری آب آبیاری از 1.88 به 7.22 دسی زیمنس بر متر، عملکرد دانه و کاه گندم کاهش معنی داری نداشت. علت این مشاهده افزایش وزن هزار دانه و شاخص برداشت با افزایش شوری از 1.88 به7.22 دسی زیمنس بر متر بود. با افزایش شوری آب آبیاری به 14.16 دسی زیمنس بر متر عملکرد دانه و کاه حدود 50 درصد کاهش یافت. این کاهش به دلیل تاثیر منفی افزایش شوری بر طول سنبله، تعداد سنبلک بارور، تعداد دانه در سنبله و تعداد کل سنبلک‌ها و افزایش تعداد سنبلک عقیم با افزایش شدت تنش شوری بود. بررسی اثرات متقابل شوری و کود سولفات آهن نشان داد که بیشترین میزان عملکرد دانه در شوری‌های آب ابیاری 1.88، 7.22 و 14.16 دسی‌زیمنس بر متر به ترتیب از مصرف 40، 20 و صفر کیلوگرم در هکتار کود سولفات آهن حاصل شد. بنابراین، به نظر می‌رسد با کاهش کیفیت آب آبیاری (افزایش شوری و نسبت جذب سدیم) مقدار آهن مورد نیاز گندم جهت حصول بیشترین عملکرد کاهش می‌یابد.

Effects of irrigation water qualities and iron sulphate application rates on wheat (Triticum aestivum L.) yield and yield components

IntroductionThere is an increasing trend in salt affected lands and it plays a crucial role for reduced crop production. Associated with Social and economic dimentions such as employment losses and environmental degradation (Butcher et al., 2016), it is estimated that annual losses of yield due to salt induced land degradation is US$ 27.3 billion globally (Qadir et al., 2014). In addition, it is well documented that application of chemical fertilizers usually improve plant performance under saline conditons but results in plant fertilizer requirement under salt affected soils are contrary. While there is little evidence of yield benefits due to application of fertilizers in salinized fields at rates beyond optimal in nonsaline conditions, there is enough evidence indicating that soil salinity does not affect or decrease plant fertilizer needs (Hanson, 2006). These contradictory results can be attributed to the types of experiments (field, greenhouse or laboratory), composition of the saline substrate, studies conducted over the short term vs. the long term and many other differences in experimental conditions (Grattan and Grieve, 1999).The salinity stress may modify the Fe fertilizer management for wheat production under arid and semiarid conditions of Yazd peovince with wide range of irrigation water qualities. Accordingly, the objectives of this field study were to (a) evaluate the interactions between Fe nutrition and the salinity of irrigation water and their effects on wheat growth and (b) test the possibility of wheat improvement at saline conditions by applying higher levels of Fe fertilizer. Materials and methodsA field experiment was conducted on wheat at Sadooq Salinity Research Station, Ashkezar, Yazd, Iran. The soil at the experimental site was calcareous with 30.92% total nutrient value, sandy loam texture, pH 8.06 and 0.22 % organic carbon. Mean annual temperatue is 18°C and precipitation is 70 mm. The treatments, four potassium sulphate application rates (0, 100, 200 and 300 kg ha1) and three irrigation water qualities (1.88, 7.22 , 14.16 dS/m), arranged in a randomized block, split plot design with three repelications. Consisting 12 rows of wheat, each field plot was 3*5 m. All plots received common agricultural practices including tillage and fertilizer application. Rgarding typical recommendations and guidelines for this region and soil type (Balali et al., 2000: Moshiri et al., 2015), all fertilizers, except urea that applied in 4 splits, were soilapplied before plnating and included 100 kg ha1 triple superphosphate, 40 kg ha1 ZnSO4, 40 kg ha1 MnSO4 and 20 kg ha1 CuSO4. To model the relationship between plant properties and irrigation water salinity, the data were subjected to different regression models at the probability level of 0.01 and 0.05 with the help of the Sigmaplot software. The analysis of variance for different parameters was done following ANOVA technique. When F was significant at p ≤ 0.05 level, treatment means were separated using DMRT. Results and discussion The results showed that increasing irrigation water salinity to 7.22 dS/m did not significantly affect wheat graine yield. This is due to the positive effect of salinity on 1000 seed weight and harvesting index. At the same time, the results showed 50% decrease in wheat grain and straw yield due to the increase in the salinity of irrigation water from 1.88 to 14.16 dS/m. The heighest graine yield for treatments irrigated with irrigation water salinity of 1.88, 7.22 and 14.16 dS/m was obtained from application of 40, 20 and 0 kgha1 FeSO4, respectively. Overall, it was concluded that salinity stress beyond salt tolerance decreased wheat requirement to iron sulphate fertilizer.