Assesment of the water - salinity production function models - Canola application in the Mashhad area

Water shortage in nature، especially in arid and semi-arid regions، often related to a decrease in water quality. This research is applied in loamy gravely field area which is located in 25 km away from city center of Mashhad in 1390-1390 and 1391-1392 cultivate years. The followed experimental design was randomized in split- split plot complete block in which four different levels of salinity (0. 5، 5، 8 and 11 dS/m، are respectively in S1، S2، S3 and S4 levels) as the main plots، four irrigation levels as subplots (supply 125، 100، 80 and 50% water necessity، I1، I2، I3 and I4 Respectively) and two cultivars of canola (Hyola401 and RGS003) as the sub-sub plots in three places. Log -linear function of the entre salinity in I4 treatment yield higher is estimated grains application more than reality. Based on the results of quadratic functions and the higher order estimates are better than the other two functions. The coefficient of R2 determination values is shown that the rate of Hayola cultivars and RGS، quadratic function with R2=0/99 and R2 = 0/8 would be first level. In contrast، the minimum numbers of Hayola and RGS logarithmic and linear functions were respectively in the next ranking. The RMSE indices show that the total higher amount of Hayola cultivar and RGS are 12/5 and 8/17 percentage yield less (according to the CRM -positive) estimates of the real values while the quadratic function total amount of 11/7 and 6/4 % performance for less (due to the positive CRM) are have been estimated the actual values. Thus، according to the occurrence comparison these indices for different functions and a final ranking is assigned to a quadratic function، this function is optimized as a function of the combined conditions of low salinity and irrigation Cultivars of Hayola and RGS which would be introduced in Mashhad.