A COMPARATIVE STUDY FOR IMPACT OF LOW PHOSPHORUS FERTILIZATION IN DIFFERENT COMBINATIONS WITH SULPHUR, GYPSUM AND PHOSPHOREIN ON TOMATO GROWTH, MINERAL STATUS AND PRODUCTIVITY.

Abstract

Two field experiments were conducted at Kalabshow district, Dakahlia Governorate during two successive summer seasons of 2007 and 2008 to study the effect of phosphorus fertilizers,i.e., super phosphate and rock phosphate in different combination with gypsum, sulphur and phosphorein on growth ,mineral composition and productivity of tomato cv. Super marmand . The experiment included fourteen treatments arranged in randomized complete block design. The treatments contained two sources of phosphorus (P) fertilizers [super phosphate (SP) and rock phosphate (RP) at 100% from recommended dose (RD),i.e,75KgP2O5] and different combination of SP or RP at low rate (65%),i.e,52.5 KgP2O5 of RD) with gypsum (G),sulphur (S)and phosphorein(Phn). The main results were as follows: 1- Addition of super phosphate(SP) at 65 % of the recommended phosphorus rate(RD) with gypsum(G) and phosphorein(Phn) as soil amendment had a significant effect on number of leaves per plant, plant height , roots& shoots and total dry weights per plant as well as relative dry weight (%)during the two seasons. 2-Application of rock phosphate (RP) at 65 % of the recommended phosphorus rate RD) resulted in significant decrease of foliage concentration of N and P as well as the N, P ,K total uptake from N,P,K in both seasons. 3- The highest significant N and P concentration and N, P and K uptake were resulted from application of super phosphate (SP) at 65 %from RD in the presence of gypsum (G) and phosphorein (Phn) at both seasons. 4- Addition of the recommended phosphorus rate as super phosphate(SP) or applying (SP) at 65% from RD with gypsum and phosphorein showed the most superior effect regarding average fruit weight, number of fruits and fruit yield of tomato plant as well as total yield per feddan. 5- Application of super phosphate (SP) at 65 %with gypsum (G) and phosphorein (Phn) resulted in 6.45 % increment in the total yield comparing to the control treatment (average of the two seasons) . 6- Applying super phosphate (SP) at 65% from RD with gypsum (G) and phosphorein (Phn) showed the superior significant values for most fruit quality, i.e., T.S.S %, Vit C and total carbohydrates content of tomato fruits. In general, this study demonstrated that it is possible to produce highest growth, yield and quality of tomato plants by applying super phosphate at 65 % of the recommended phosphorus rate with 2.5 ton/feddan of gypsum and 1 kg/feddan of phosphorein. Moreover, the phosphatic fertilization can be reduced by 35 % of the recommended rate beside reduction of chemical pollution.