ESTIMATING OF CROP COEFFICIENT FOR WATERMELON AND ONION PLANTS UNDER DELTA NILE CONDITIONS

Abstract

The study was conducted to calculate scheduling irrigation and estimate the Kc for different growth stages for onion (Allium cepa L.) and watermelon (Citrullus lanatus) in Egypt. The study was carried out at the Experimental Farm of the Institute of Post-Graduate Studies and Research in Arid Lands, Ain Shams University in Shubra El Kheima, Qalyubia Governorate, Egypt. Two experiments were conducted in 2014/2015 and 2015/2016 seasons under the conditions of volumetric lysimeter. The experiments were laid out in a completely randomized design with three replications. Each experiment included three levels of crop evapotranspiration (75, 100, and 125% of ETc) for each crop and three types of soils (clay, sand, and sandy clay). Thus, the experiment consists of 27 plots (27 concrete lysimeters units) for each crop. Each unit is 1 x 1 x 1 m = 1m2. In onion experiment, each lysimeter contained two rows and contained 40 plants in total, while each lysimeter in watermelon experiment contained two plants. The statistical analysis was conducted using the CoStat Package Program (Version 6.303; Co Hort Software, USA). Data were subjected to the analysis of variance (ANOVA). The variances among means were compered by Duncan’s Multiple Range Test (Waller and Duncan, 1969). All statistical determinations were made at P ≤ 0.05. Growth characteristics recorded for onion were plant length, number of leaves, SPAD readings, bulb diameter, neck diameter, bulbing ratio, yield and yield quality (dry matter, T.S.S and concentrations of Ca and Cu in bulb as well as marketable bulb yield). Also, growth characteristics recorded for watermelon were plant length, SPAD readings, fruit size, fruit and pulp diameter, average of fruit weight, dry matter and humidity of fruit, yield and yield quality (total soluble solids percent, and concentrations of Ca and K) in fruit. In addition, crop water use parameters were recorded for both crops.