Evaluation of Nutritional Status of Squash by Deviation from Optimum Percentage (DOP) Method in Khoy Region

 Deviation from the optimum percentage (DOP) is an important method for interpretation of the results of chemical analysis and diagnosis of nutritional status of plants. In order to evaluate the nutritional status of squash (Lagenaria Vulgaris) through DOP, 122 leaf samples were collected from squash fields of Khoy region and N, P, K, Ca, Mg, Fe, Mn, Zn, Cu and B were analyzed. The squash fields were divided into high and low yielding groups. The mean of nutrients concentration in high yielding-fields was selected as norms for the calculation of DOP indices. DOP indices showed that macro- and micro nutrients requirement as follow K>P>Mg>Ca>N and Zn>Fe>B>Cu>Mn respectively. So nitrogen had the most positive index but potassium and zinc had the most negative indices among nutrients. DOP nutritional balance index was much more than zero indicating nutritional imbalance in this region. Finally, it was concluded that K and Zn deficiencies are more critical in reduction of the squash yield and the application of their fertilizers can improve growth and yield of squash in the region.