Quality of tomato fruits fertigated with potassium in soil with black polyethylene mulch.

An experiment was conducted to determine the effects of potassium fertigation and black polyethylene mulch on tomato fruits composition and quality. It was carried out from September/1995 to January/1996, corresponding to the end of cold and dry season and beginning of hot and rainy period, on a cambic yellowish podzolic soil at the Federal University of Viçosa, in Brazil. Treatments were set out in a randomized block design, with five replications, as follows: (A) manual application of 40% of recommended K rate at seedling transplantation and manual sidedress application of 60% (control plot); (B) manual application of 40% of recomended K rate at seedling transplantation and 60% by fertigation; (C) manual application of 40% of recommended K rate at seedling transplantation and 60% by fertigation, with black polyethylene mulch; (D) application of 100% of K rate by fertigation and (E) application of 100% of K rate by fertigation, with black polyethylene mulch. Each plot constituted 28 plants, spaced 1,0 x 0,5 m, with data collected for the ten central plants. The dry matter percentage and N-NH₄ ⁺, N- N0₃ ^_, N-total, P, K, S, Mg concentrations and K/Ca ratio in tomato fruits were not influenced by fertigation and black polyethylene mulch. Ca concentration raised with total K fertigation and black polyethylene mulch use. On the other hand, the K/Mg and K/ (Ca+Mg) ratios in tomato fruits generally were smaller in treatments with total fertigation and black polyethylene mulch. Total solids, titratable acidity, flavor, pH and vitamin C in tomato fruits were not influenced by fertigation and black polyethylene mulch, while the lycopene and total carotenes, when the potassium fertigation was total, increased with the black polyethylene mulch.

Lycopersicon esculentum; chemical and organoleptics characteristics; plasticulture.