ارزیابی صفات کیفی و فیزیولوژیک سیب‌زمینی تحت تاثیر رژیم‌های آبیاری و سطوح کود نیتروژن

In order to study the effects of different levels of irrigation and nitrogen on tuber yield, qualitative and physiological characteristics of potato crop, a split plot experiment based on the randomized complete block design was carried out with four replications at Research Center of Agriculture and Natural Resources of Chahar Mahal va Bakhtiari province, in 2013. The levels of irrigation were Ir1, Ir2 and Ir3 (100, 75 and 50% of the water requirement of potato after emergence by the end of the growing season, respectively) as the main factors and nitrogen fertilizer treatments were N1, N2, N3 and N4 (100, 66, 33, and 0% of plant nitrogen requirement) as the secondary factors. Results indicated that marketable tuber yield was similar in Ir1 and Ir2 treatments (about 56 and 51 tons per hectare, respectively), but drought stress (Ir3) leads to the production of about 31.7 tones marketable tubers per hectare. Reducing nitrogen consumption also had a negative effect on tuber yield per unit area. Drought stress significantly raised tuber dry matter percentage. The content of soluble sugars and proline increased under drought stress condition but nitrogen treatments had no effect on these physiological indices. Leaf chlorophyll content decreased due to drought stress and reduction of nitrogen consumption. Drought and reduced nitrogen fertilizer application had a positive effect on the percentage of tuber starch. Nitrogen treatments had a significant effect on tuber nitrate content. Tuber nitrate varied from 29.32 to 52.04 mg per kg fresh weight of tubers (N4 and N1 treatments, respectively).