The main aim of the experimental work in this study is to assess the vegetative growth and yield of zucchini depending on the used foliar fertilizers. Field experiments were carried out during three successive growing seasons in the experimental field of the Department of Horticulture at the Agricultural University in Plovdiv, Bulgaria. Zucchini cv. Izobilna F1 and Black Beauty were used in the experiments. The field experiments were carried out by means of a randomized block design in four replications. The complex foliar fertilizers Hortigrow® (mineral) and Humustim® (organic), in three concentrations, were used. A random sample of the plants from each treatment was used for evaluating the stem length, number of leaves per plant, fresh weight of the plant (the sum of the stem fresh weight and leaf fresh weight). In order to establish the plant productivity, the early yield of the first 5 harvests was determined, where as the average total yield was recorded during the whole harvesting period.
The assessment of the plant growth development and yield indicated that the application of organic foliar fertilizer Humustim® 0.3% resulted in the longest stem, greatest number of leaves as well as in increasing the early and total yields. It is followed by the variant that used the water-soluble mineral fertilizer Hortigrow® – 0.2%. It is concluded that foliar fertilizers could enhance the productivity of zucchini and foliar fertilizer application could be employed for increasing the efficiency of early field zucchini production.