Evaluation of drought stress tolerance and its effects on growth characteristics in some accessions of colocynth (Citrullus colocynthis (L.) Schrad)

Colocynth is one ofdrought tolerant species, which is widely distributed in desert regions of Iran. The experiment was performed in research field of University College of Agriculture and Natural Resources, University of Tehran placed in Karaj, as a split plot based on randomized complete block design which irrigation levels were as main plot in two levels (100% and 60% field capacity) and accessions were as sub plot in seven levels (Kerman, Sistan and Baluchestan, Khuzestan, Yazd, Hormozgan, Bushehr and Isfahan).At the end of growth period, yield, yield components and indices of drought resistance were evaluated in two stress and non-stress conditions for screening of colocynth accesstions. The highest yield in stress and non-stress conditions belonged to Kerman (5.73 kg/plant) and Isfahan (2.54 kg/plant) accessions, respectively. Yield components of Isfahan accession showed the lowest variation percent in stress and non-stress drought conditions. Investigation of drought resistance indices and correlation between yield and these indices and principal components analysis showed that Isfahan accession was tolerant with sustainable yield, Yazd and Hormozgan accessions were semi tolerant with relative sustainable yield and Kerman accession had high yield in non- stress and stress drought conditions.Khuzestan and Bushehr accessions were low yield and high sensitivity to drought stress and Sistan and Baluchestan accessions were low yield and relative tolerant to drought stress. Generally Isfahan accession had high tolerant to drought stress and useful for commercial watermelon breeding programs.