Document Type : Original Article
Authors
1 University of Birjand, Iran
2 Faculty of Agriculture, Shahid Chamran University of Ahvaz, Iran
Abstract
The main factor for managing and scheduling irrigation in dry zone, recognition of plant response to dryness stress. Most irrigation water in Birjand area have saline solution, therefore, salinity stress should be considered at the stimulatingly. Hens, this study was conducted in order to obtain the optimum depth of irrigation scheduling, considering dryness and salinity individually and stimulatingly during 2006 agriculture year, in agricultural research station at Birjand university. The experiment had three replications according to a randomized complete block design with split plot layout (factorial form), which considered three levels of water salinity (1.4, 4.5, 9.6 dS m-1) as main plot and four levels of irrigation water (50, 75, 100, 125 % of plant water requirement) and two wheat varieties as sub plot. The irrigation depth for different salinity levels and the two cultivars was determined. The crop yield under different conditions was determined using production functions, than the optimum irrigation area net income for available water (10000 m3) was assessed. The results showed that by increasing salinity stress, the irrigating depth of both wheat cultivars were a little decreased that was not reflected in real condition. The reason for reduction in irrigation depth is related to water price for different salinity levels that was accounted as constant, where, the crop yield during various salinity stress severities would be different. Also, under dryness stress, and increase salinity stress conditions for both wheat cultivars, the irrigation depth, were increased. The reason for this increase in irrigation depth was reduction in yield high levels of salinity stress that was resulted from changing of production function to the irrigating depth. Therefore, at high salinity stress levels, deficit irrigation would malfunction and would not be economically feasible. For all available water levels, the irrigation depth was higher for Ghods cultivar then Roshan cultivar. This factor was responsible for obtaining optimum irrigation area for Ghods cultivar compared to Roshan cultivar in various salinity levels and resulted that the net income of Roshan cultivar was more than Ghods cultivar in all levels. Overall, where the available water quantity is considered and quality is not favorable (saline) using Roshan cultivar is highly more economical in Birjand region.
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