Determination and Validation of Diagnosis Norms of Nutrients for Wheat in Moghan Region

The diagnosis and recommendation integrated system (DRIS) and deviation of optimal percentage (DOP) methods are used for interpreting the results of leaf analysis. In the present study, leaf samples from 98 wheat fields were collected in Moghan region of Ardebil province in 2014-2015. The nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), manganese (Mn), copper (Cu) and boron (B) concentrations were determined. The wheat fields were grouped into high- and low-yielding subpopulation by using mean ± SD; then, the DOP and DRIS indexes were calculated. Based on the DOP and DRIS indices, the nutrient requirement order were determined as: Zn> Cu> Fe> Mn> P> N> K = Ca> Mg> B, and Zn> Mn = Fe = Cu> N = P> B > K> Mg > Ca, respectively. These results showed that there was a high degree of similarity between the two methods in interpreting the results of leaf analysis. After identifying the negative indices of some micronutrients (Zn, Fe, Mn, and Cu), a factorial field validation experiment was conducted with foliar application of Fe, Zn, Cu, and Mn using a randomized complete block design with three replications in two separate fields, with a total number of 96 plots, in 2015-2016. The results of the validation experiment showed marked decrease in the DRIS and DOP indices, indicating a more balanced concentration of nutrients. The order of the nutrients requirement in the DRIS method was Mg> P> N = K> Fe = B> Mn = Zn> Ca = Cu and in the DOP method Mg > N > Mn > P > K = Fe = Cu > Zn = B > Ca, which indicated the correct diagnosis of micronutrients deficiency by both studied methods. Micronutrients treatment in the validation test led to 28% increase in yield by balancing the nutrients. Since micronutrients, especially Zn, ranked the first priority of the deficiency for wheat in Moghan area, micronutrients should be used along with the phosphorus and nitrogen fertilizers.