Investigation of irrigation by sugarcane drainage water on soil quality specifications and yield of 20 genotypes of wheat in south of Khuzestan

According to the growing human need for food production, using of unconventional water is defined as one of the strategies for overcoming the water crisis in the world. Drainage water recirculation for producing economic sustainable agricultural products can be very useful to management of drainage water environmental impact and adapt with water crisis in the world. For this purpose, overcoming on salinity stresses and preservation of soil quality during cultivation are so important. Studying on salinity effect of irrigation water on wheat yield and soil salts has a long history in the world but genotype and climatic conditions are very influential on the results, so do this research can be very useful. This research has been conducted to determination the best genotype of wheat and analysis of soil behavior in the study of solutes in it.

This research was conducted in 2018-2019 in an experimental farm of AmirKabir Agro-Industry Sugarcane Company using split plot design with randomized complete block with three replications, yield reaction of 20 genotypes of wheat to irrigation with sugarcane drainage water farms was investigated. Also applied water volume, farm water requirement and drainage water effect on soil salts were analyzed. Main plots was irrigation water quality with two quality: 1- fresh water with EC=1.3 dS m-1 and 2- sugarcane drainage water with EC=7.0 dS m-1. Sub plots were 20 genotypes of bread and durum wheat which is cultivated in 8 lines and 20 cm distance. Water requirement was determined by 10-years climate data and wheat crop coefficient and calculated using FAO Penman-Monteith method. Field irrigation management was performed based on water requirement information and considering soil physics, leaching requirements and effective rainfall. Extracted information included volume of applied water, salt and moisture soil samples, water and drainage water quality samples, physical soil specifications, grain yield, biological yield, spike per square meter, grain per spike, 1000-grain weight and flowering date. 

Results showed that using sugarcane drainage water reduced the mean yield by 9.7% and decreased irrigation water productivity from 1.08 to 0.97 kg m-3. There is no significant difference between Bow, Shoele, Narin, Bloudan, Sarang, Irna, Spn and Pishtaz varities for using Karun River and drainage water in terms of grain yield, biological yield, spike per square meter, grain per spike, 1000-grain weight and flowering date, so it can be concluded that these genotypes are stable in different environmental conditions. Stress tolerance index varied from 0.57 to 1.22 among different genotypes. 1-63-31 and Narin genotypes had the highest and the lowest tolerance indices, respectively. Bam and Shoele genotypes were in the mean group with 0.92 and 0.89, respectively. Overall, Sistan, 1-63-31, Bow, Shoele, Sirvan, Sarang, Irna, Khalil, Barat, and Pishtaz with an index above the mean index (0.90) are among the most tolerant and it can be concluded that they can be considered as the most tolerant figures. Also Barat genotype had maximum applied water and total water productivity with fresh water irrigation which were 1.35 and 1.14 kg m-3 and Sistan had maximum water productivity for drainage water in these parameters which were 1.16 and 0.98 kg m-3. Soil results showed that using agricultural drainage water for irrigation not only led to changing farm soil from non-saline to saline condition, it closes to become sodic. Under drainage water cultivation conditions, soil quality will be compromised, which will require new development of irrigation management, leaching and cropping patterns. In these conditions, accurate knowledge of the time and amount of water required for wheat, irrigation with high efficiency and application of appropriate amount of leaching water with proper field drainage, can be effective.

This research was conducted to reaction investigation of various genotypes of wheat in condition of using sugarcane drainage water. Due to the fact that in the middle of autumn and late winter, the drainage of sugarcane fields is low and in this period, most of wheat water requirement is supplied by rainfall and the most important irrigation events start after winter in Khuzestan, so wheat had been chosen for this research. Results showed that yield decrease in drainage water farm for 20 studied genotypes was about 9.8% which is varies between 30.6% for ChamranII to 8.6% for Sistan genotypes. Applying drainage water as irrigation water can cause negative effects on farm soil quality in short term and studying of this behavior by using simulating models can be very useful. For reduction of negative effect of drainage water on soil quality, it is necessary to pay enough attention to the amount and time of irrigation at the last 2 or 3 irrigation events.