THE EFFECT OF NITROGEN FERTILIZATION LEVELS AND APPLICATION DATES ON THE VEGETATIVE GROWTH AND PRODUCTION CHARACTERISTICS OF ZUCCHINI SQUASH (Cucurbita pepo L.) (UNDER DRIP IRRIGATION SYSTEM)

Abstract

A field experiment was conducted for the two agricultural seasons 2014/2015 and 2015/2016 at a farm located in the Delta of Tuban in Lahij Governorate, Yemen, at latitude [North 16, 53, 44] and longitude [East 30, 02, 13]. The study aimed to find out the effect of nitrogen fertilization levels and their application dates on the characteristics of vegetative growth and total production of zucchini squash (Cucurbita pepo L.) under the drip irrigation system, in order to know the best level of nitrogen fertilization and to determine the best dates to add them to the characteristics of vegetative growth and total production of zucchini plants, use the complete sector design randomization in four replications, the study included 15 treatments consisting of five levels of nitrogen fertilization (Urea) (00, 50, 100, 150, and 200 kg Nitrogen/ha) and three dates of addition (one week after germination, at the beginning of flowering, and at the beginning of fruit setting). Nitrogen fertilization at 200 kg nitrogen per ha was significantly superior in plant height, number of leaves, leaf area plant compared to the control (without fertilization) during the two seasons of the study, and the dates of adding nitrogen fertilization had a significant effect on most studied growth characterizations. Where the first application date (one week after germination) gave the best results in the characteristics of plant height, stem diameter, number of leaves, leaf area, wet weight, dry weight, and total yield.