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Abstract
The Diagnosis and Recommendation Integrated System (DRIS) has been proposed to determine nutrient balance in plants at different stages of growth. The DRIS index for each nutrient allows ranking of nutrients in order of their deficiency. Preliminary DRIS norms for potato (Solanwn tuberosum L.) were developed during the 1991 growing season in Damavand area located 70 km. northeast of Tehran. The soil and leaf samples at flowering stage (early tuber development stage) were collected from 50 different farms. Average concentrations of nutrients in both high‐ and low‐yielding populations were calculated. The following average foliar nutrient concentration were obtained from the high‐yielding populations: N = 5.22, P = 0.38, K = 4.20, Ca = 1.50, and Mg = 0.65 percent; and Fe = 150, Mn = 50, Zn = 40, Cu = 11, and B = 38 ppm. The average nutrient concentrations for the low‐yielding population were close to those in high‐yielding ones except for K which was 3.23 in contrast to 4.20‐percent. There was no significant relationship between different soil nutrient availability indices and yield except for K. The DRIS indices ranked K as the most limiting nutrient in the low yielding farms with only one exception. It seems high rates of N and P fertilization have created a lack of balance between these nutrients and K.
As a result of this study, the following appropriate norms for potato leaves are suggested for the calcareous soils of Iran: N = 4.5, P = 0.30, K= 5.00, Ca = 1.50, and Mg = 0.65 percent; and Fe = 150, Mn = 50, Zn = 40, Cu = 11, and B = 38 ppm. These results will be verified by field fertilizer experiments for N, P, K, Zn, and Fe which are some times deficient in potato soils.
Notes
This research was performed as a part of requirements for M.Sc. Thesis, presented to the Department of Soil Science, Tarbiat Modarres University, 1992.
Instructor, Agriculture Educational Center, Karaj, and Associate Professor, Soil Science Department, Tarbiat Modarres University, Tehran, Iran, respectively.