The effects of deficit irrigation on nitrogen consumption, yield, and quality in drip irrigated grafted and ungrafted watermelon

The aim of this study is to determine the effects of deficit irrigation on nitrogen consumption, yield, and quality in grafted and ungrafted watermelon. The study was conducted in Çukurova region, Eastern Mediterranean, Turkey, between 2006 and 2008, and employed 3 irrigation rates (full irrigation (I100) with no stress, moderate irrigation (DI70), and low irrigation (DI50); DI70 and DI50 were considered deficit irrigation) on grafted (CTJ, Crimson Tide+Jumbo) and the ungrafted (CT, Crimson Tide) watermelon. The amount of irrigation water (IR) applied to the study plots were calculated based on cumulative pan evaporation that occurred during the irrigation intervals. Nitrogen consumption was 16% lower in CTJ plants than in CT plants. On the other hand, consumption of nitrogen was 28% higher in DI50 plants than in DI70 plants while it was 23% higher in DI50 plants than in I100 plants. By grafting, the average amount of nitrogen content in seeds, pulps and peels for CTJ was 30, 43 and 56% more than those of CT, respectively. The yield and the quality were not significantly affected by the deficit irrigation. In this respect, grafting of watermelon gave higher yield, but, it had a slight effect on fruit quality. The highest yield values of 16.90 and 19.32 kg plant-1 in 2008 were obtained with I100 and in CTJ plants, respectively. However, DI50 treatment could be taken into account for the development of reduced irrigation strategies in semiarid regions where irrigation water supplies are limited. Additionally, the yield increased by applying CTJ treatment to the watermelon production. © 2015 Chinese Academy of Agricultural Sciences.Firat University Scientific Research Projects Management Unit: ZF2006D16, ZF2008BAP1The authors would like to gratefully acknowledge the University of Çukurova, Turkey, for providing funding through the Scientific Research Projects of Çukurova University (ZF2006D16 and ZF2008BAP1). The authors thank to Dr. Elif UZ, Department of Molecular Biology and Genetics, for her help in preparing the manuscript