the impact of reduction in growth season of autumn crops on sustainable use of groundwater resources

currently, a considerable amount of water usage in various sectors of the khorasan razavi province: agriculture and industry etc., is supplied through the restricted underground water resources. however, the current trend of water usage in the various sectors, including agriculture, is a cause for serious concerns regarding the durability of quantity and quality of available water to meet future. to achieve an approach for reducing water consumption in the agricultural sector of the province, and to determine the effects of changing the planting date on production potential of wheat, barley, and rapeseed, as the most important autumn crop in province, a study was carried out in the agriculture and natural resources research and education center of khorasan razavi. during the years that this study targets, replicated trials for all crops were carried out as split plots in a randomized complete block design with three replications, so that planting dates as main plots and a diversity of varieties of these crops were studied through subplots. results indicate that grain yield potential is considerable, with respect to the shortening of growth season for the aforementioned grains. however, compared to favorable grain yields a reduction in crop output was identified. however, it seems that a reduction in the growth season of wheat, barley, and rapeseed along with elimination of autumn irrigations is possible. in general, the outcome of the trial years results show that the optimal choice for the planting date of wheat, barley, and rapeseed, by eliminating irrigation in mashhad, is the pending culture (i.e., when a decrease in temperature stops the seeds from germinating and the seeds sprout after the passage of the winter cold). but for wheat and barley this period may continue until 20th of february, although the optimum planting date is still recommended.