THE EFFECTS OF HUMIC AND BIO-FERTILIZERS ON GROWTH AND YIELD OF GREENHOUSE TOMATOES

Optimization of growth, yield and quality of vegetable crops in an integrated manner is achievable through efficient use of organic, inorganic and biological sources of nutrients. The present study aimed to evaluate the effect of foliar or soil application of humic and bio-fertilizers, on the growth and yield of greenhouse tomatoes. The experiment was carried out during three consecutive years in an unheated greenhouse at Maritsa Vegetable Crops Research Institute, Bulgaria. A commercially available humic fertilizer, produced from vermicompost, and bio-fertilizer, containing Lactobacillus casei, Lactobacillus lactis, Phodopseudomonas palistris, Sаccharomices cerevisiae were tested. Soil application of both fertilizers was performed only once, a week after transplanting, while the foliar application was conducted three times with 10-14 day intervals after transplanting. In order to assure uniform background of the experimental plots, the soil was supplemented with mineral fertilizers according to the recommendations following the soil analysis. The results indicated that soil application of both fertilizers stimulated the growth of tomato plants. The total tomato yield was increased with 19 and 21% after soil application and by 13 and 14% after foliar application of bio-fertilizer and humic fertilizer, respectively. The enhancement of the total yield was attributed to the enhancement of the mean fruit weight, which increased by 14-30 g per fruit. The early yield and the number of fruits per plant were not influenced by the applied humic or bio-fertilizers. The results indicated that the utilization of bio-fertilizer or humic fertilizer in fertilization practices can lead to higher yield of greenhouse tomato with improved market quality.