Phosphorus-zinc Interactions in Potato Production Cultivars.

It seems that the synergy between adding P and Zn together can substantially increase tuber yield and quality in situations where this phenomenon occurs. Previous research indicates negative effects on potato when excess phosphorus(P) fertilizer is applied. The standard grower practice is to uniformly apply P to an entire field, which results in 30%-45% of the field receiving excess P fertilizer. One possible approach is based on a physiological coupling of excess P inducing a zinc (Zn) deficiency. The objectives of this project were to evaluation the interaction effects of P and Zn fertilization on the yield of three potato cultivars. A two years field project was excuted. Treatments arranged in a split-plot randomized complete block design with three replications. Treatments were factorial combinations of three P2O5 rates(0, 75 and 100 kg ha-1) and three rates of ZnSO4 (0, 50 and 100 kg ha-1) as a subplot and three potato cultivars( Marfoona, Santee and Mara-dona, Early, middle and late season respectively) as a main-plot. Two years combined analysis of variances, resulted that Mara-dona cultivar had significantly maximum tuber yield. In Marfoona and Santee cultivars, tuber yield differences didn't significant. Significant responses were observed both for P and Zn fertilization, as well as a significant interaction between the two. The heights tuber yield resulted from 75 kg ha-1 (as P2O5) and 50 kg ha-1 (as ZnSO4). It was concluted if the soil test showed the critical soil aviable P and Zn, in Mara-dona cultivar, application of 150 kg ha-1 triple super-phosphate and 50 kg ha-1 ZnSO4 and 75 kg ha-1 triple super-phosphate and 50 kg ha-1 ZnSO4 in Marfoona and Santee recommended as soil application in tillage stage. Application of P without consideration of Zn nutrition is potentially a serious management problem for potatoes grown in Zn-limiting soils. Further research is needed to confirm this effect and to explore rate and ratio effects of adding P and Zn fertilizers.