Determination of water- salinity production function by taking time performance and the assesment production indexes of forage sorghum

The research in order to identify the best function salinity of sorghum forage yield and harvest time was carried out in the Sistan region.Testing in three levels of salinity (2, 5 and 8 ds/m) and four levels of irrigation water (50, 75,100and 120% water requirement) were conducted at three time points and four linear production function, cob-douglas, quadratic and transcendental evaluated. for each harvest production function was evaluated separately.Then, considering the time of harvest, evaluated and the best function was determined. After determining the best function to separate effects of salinity and irrigation water from the final production indicators of the depth and salinity of water, Marginal rate of technical replacement for salinity and water irrigation , the final output value of the irrigation water depth and salinity were used in each drawing. Final manufacturing index showed the depth of irrigation water for irrigation to increase water depth of one centimeter per impression, first impression least change operation (1.22) and third harvest the maximum amount (2.9) had. Final Manufacturing Index showed to salinity Reduction in salinity low performance in the second and third were less than first impressions and is the second largest fresh forage yield The final replacement rate the quality and quantity of water than fresh forage yield of forage sorghum showed For the performance does not change with increasing salinity units, should be 5.86 inches in the first harvest, 1.97 and 1.72 second harvest third harvest irrigation water depth increases.