Document Type : Original Article
Author
Assistant Professor, Department of Agricultural Engineering Research, Agriculture and Natural Resources Research and Education Center of Semnan (Shahrood), Agricultural Research, Education and Extension Organization (AREEO), Shahrood, Iran.
Abstract
Extend Abstract
Introduction
In order to increase water productivity, the use of modern methods of pressurized irrigation is one of the effective solutions. These methods can play an important role in conserving water resources by reducing water losses, increasing irrigation efficiency and allowing more accurate management of time and amount of applied water. Sprinkler irrigation is one of the suitable options for wheat fields in semi - arid regions. The Rain flat sprinkler irrigation system as a relatively new sprinkler method, requires less work pressure than conventional sprinkler methods and therefore energy consumption decreases. In addition, installation and operation of this system is simpler and faster and can be an appropriate option for irrigation management in water deficit conditions. Therefore, due to the limited water resources in Semnan province and the importance of wheat production and also for introducing the Rain flat sprinkler irrigation system, this study was conducted to investigate the effect of irrigation interval and different levels of water supply on yield and yield components of wheat.
Methodology
The aim of this study was to investigate the effect of irrigation interval and different water levels on yield and yield components of wheat in Rain flat sprinkler irrigation method for two years. The experiment was conducted as a split plot in randomized complete block design with three replications in Shahrud Agricultural Research and Education Center. Three irrigation intervals (4, 5 and 6 days) were allocated to main plots and three irrigation levels (100 ,80 and 60 %) in sub plots. Sprinkler irrigation pipes were placed at 4-meter intervals between planting rows. The length of planting rows was 8m. By using the Penman - Monteith method, water requirement of the plant was determined. At the end of growing season, wheat was harvested and yield was measured in each plot. Yield components including plant height, thousand grain weight and grains number per spike were determined for all treatments. Harvest index was calculated from the division of seed weight to total weight of vegetative and reproductive organs.
Results and Discussion
Results showed that the highest grain yield was achieved in irrigation interval of 4 and 5 days whereas irrigation interval of 6 days decreased yield. The effects of water supply, the treatments of 100 % and 80 % water supply had the highest yield and the 60 % water supply had the lowest yield. Therefore, it is possible to reduce water supply from 100 to 80 percent without significant reduction of yield, but decreases from 80 to 60 percent decrease grain yield by 39.17%. The interaction of interval and water supply showed that 4 days with 100 % water, 4 days with 80 % water and 5 days with 100 % water had the highest yield. The lowest yield belonged to 6 days with 60 % water, indicating a decrease of up to 60.35 % in adverse irrigation management. The highest plant height, grains number per spike and thousand grain weight was obtained in 4 days irrigation interval, but there was no significant difference between 4 and 5 days in grain yield and harvest index. Also, plant height, grains number per spike, thousand grain weight and harvest index were in the treatment 100 and 80 percent of water supply in the top group, while reducing water supply to 60 percent reduced the yield and its components significantly. The results show that in Rain flat sprinkler irrigation system, with appropriate management of irrigation interval and irrigation interval equal to 5 days and supplying 80 % water requirement, both yield and yield components can be maintained in desirable condition, while increasing irrigation interval or severe water reduction, both lead to significant decrease in yield and yield components.
Conclusions
The results of combined analysis showed that irrigation interval and its combined effect with water supply level had a significant effect on most of traits. The highest plant height, grains number per spike and thousand grain weight was recorded in 4 days irrigation interval, but there was no significant difference between 4 and 5 days in grain yield and harvest index. Also, plant height, grains number per spike, thousand grain weight, grain yield and harvest index were in 100% and 80% water supply in a statistical group, while reducing water supply to 60% reduced grain yield by 17.39%. Based on results, irrigation interval of 4 and 5 days with 80% water supply was the most suitable management to maintain wheat yield by reducing water use. The results of this study indicate that optimal water management in wheat cultivation can be achieved without yield reduction by reducing irrigation water by 20 percent and adopting a 5-day irrigation interval.
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