Evaluation of crop water stress index and leaf water potential for deficit irrigation management of sprinkler-irrigated wheat

This study evaluated crop water stress index (CWSI) and midday flag leaf water potential (? ı ) on wheat (Triticum aestivum L. Adana 99) under the three different supplemental and conventional irrigation strategies using sprinkler line-source system during 2014 and 2015 in Adana, Turkey. The irrigation strategies were as follows: conventional irrigation (CI), supplemental irrigation (SI) during flowering (SIF), SI during grain filling (SIG), SI both during flowering and grain filling (SIFG). These strategies were tested under four irrigation levels 100, 75, 50, 25% and rain-fed. The CI 100 treatment achieved the highest grain yield in both seasons, followed by CI 75 and SIFG 100 . The CI 75 had the greatest water use efficiency of 1.20 kg m - 3 , and SIF 25 resulted in the lowest WUE. Grain yield and available soil water correlated linearly to CWSI. These relations could be employed in predicting the yield response to water stress. A higher grain yield was obtained when irrigation was applied at CWSI values less than 0.26, suggestingCWSI as a good indicator to improve irrigation timing for wheat. Prolonged drought in early grain filling stage led to a decline in ? ı in the advanced growth stage which in turn reduced grain yield. Significant correlations between ? ı and grain yield and CWSI were obtained, which could be useful in improving wheat irrigation water management. CI 100 is recommended when there is no water shortage; however, under water scarcity conditions CI 75 , SIFG 100 and SIFG 75 , with higher WUE and relatively higher yields, are recommended. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.Firat University Scientific Research Projects Management UnitAcknowledgements The authors would like to thank the Scientific Research Projects Unit of Cukurova University for its financial support to conduct this work

Evaluation of net return and grain quality characteristics of wheat for various irrigation strategies under the Mediterranean climatic conditions

This study evaluated the effect of different supplemental and conventional irrigation strategies on economical parameters, yield and grain quality characteristics of wheat (Triticum aestivum L., cv. Adana 99) using sprinkler line-source system during 2014 and 2015 seasons in the Mediterranean region. The irrigation strategies were Conventional irrigation (CI), Supplemental irrigation (SI) during flowering (SIF), SI during grain filling (SIG), SI both during flowering and grain filling (SIFG). These strategies were tested under four irrigation levels 100, 75, 50, 25% of crop water requirement, and a rain-fed treatment was included as control. Conventional full irrigation (CI100) treatment achieved the highest grain yield and maximum net return in both seasons. The higher deficit irrigation treatments resulted in negative net return in dry season but positive in wet season. SIFG100 and SIF100 generated a net return of 668.53 and 424.22 $/ha, respectively. CI75 produced more yield and net income in comparison with SIFG100 that although irrigation amount was less but the yield and net income were 26 and 7.65% greater; furthermore CI75 saved 23.3% of water with small grain yield reduction of 4.45% as compared to CI100. Therefore CI75 can be recommended to maximize yield and net income under scarce water conditions. In this study, higher water stress occurring in the dry year helped to improve the grain quality and made it richer than wet year. The findings showed positive response between the quality parameters such as protein content, wet gluten content and sedimentation volume, and water stress. SIFG75 treatment was the best irrigation strategy for high grain quality parameters (with small yield reduction as compared to CI100). It could be recommended to obtain high yield and good quality indicators under Mediterranean conditions. © 2018 Elsevier B.V