RESPONSE OF THOMPSON SEEDLESS GRAPEVINES TO APPLICATION OF METHYLENE UREA AND SOME SLOW RELEASE N FERTILIZERS AS APARTIAL REPLACEMENT OF THE FAST RELEASE MINERAL UREA FERTILIZERS

Abstract

Thompson Seedless grapevines were fertilized with three slow release fertilizers namely P and S coated urea and methylene urea each at 25 & 50 % of N as a replacement of the soluble fertilizer urea. Application of any one of the three slow release N fertilizers (P & S coated urea and methylene urea) was superior than using urea the fast release N fertilizer in enhancing all growth aspects , leaf pigments, nutrients (N, P, K, & Mg), berry setting %, yield and berry quality of the berries. Slow release fertilizer treatments effectively lowered both nitrate and nitrite in berry juice when compared with using urea. The best slow release fertilizer in this respect was methylene urea. Sulphur-coated urea occupied the last position in this respect. Using any slow release N fertilizer above 25% of the suitable N had no material effect on all the investigated characteristics. Fertilizing Thompson Seedless grapevines with the suitable N (80 g. N/ yr.) as 25% N via methelen urea (89 g. N/ vine / yr.) is suggested to be beneficial for improving yield and quality of Thompson seedless grapevines.