Effect of deficit irrigation at different growth stages of two Iranian melon accessions ‎on growth, yield, fruit quality and water use efficiency ‎

To evaluate the effect of  deficit  irrigation stress at different growth stages of two Iranian melon accessions  on growth, yield and fruit quality, a split- split plot experiment was conducted based on randomized complete block design with three replications at University of Zanjan. Treatments were consisted of deficit irrigation in three levels (100, 80 and 60% ETc) as main plot, stage of water deficit application in two levels (flowering and 20 days after flowering (fruit development stage) as sub plot and melon accession in two levels (Khatooni and Ivanaki) as sub-sub plot. The results showed that deficit irrigation stress were conducted at two growth stages, reduced growths index and yield. The lowest leaf area, plant height, total plant yield (6.72 kg), marketable plant yield (5.47 kg), fruit flesh percentage (50.7%) and vitamin C (1.48 mg/100 ml were obtained under  60% ETc at flowering stage. The highest value of TSS was obtained in “Khatooni” (12.04%) and “Ivanaki” (11.42%)” by applying 80% ETc at flowering stage. The highest value of water use efficiency (WUE), was achieved in “Ivanaki” and “Khatooni under 80% ETc at flowering and” 20 days after flowering stage, respectively. The Ivanki accession showed higher tolerance to water deficit. According to the results, applying 80% ETc at the flowering stage improved the fruit TSS and resulted in 40% water usage, while reduced 6.61% of fruit yield.