Impact of drought stress on morphological and physiological traits in some Iranian grape cultivars

Lack of rainfall and rising temperatures have caused problems in the agricultural crop cultivation in many areas. Grapevine is one of the most important economic products in horticulture. Due to the importance of grapes as important economic products in horticulture, identification and use of resistant cultivars to drought stress is one of the basic steps and the important goals this plant breeding programs. This research carried out in factorial experiment in randomized complete design with three replications in 2020. Experimental factors was include different levels of drought stress (level four 100, 75, 50 and 25% of water requirement) and grapvine cultivars (Gharashiliq (Ga), Rasmi (Ra), Aghshiliq (Ag), Copake Bogan (Co), Tukilgen (Tu) , Khalili (Kh)). The results of this study showed that with increasing drought stress level in 6 grape cultivars, plant growth parameters, relative leaf water content, photosynthetic pigment content decreased significantly (p <0.01), that the greatest decrease was observed at the stress level of 25% water requirement. Also, increasing drought stress levels the electrolyte leakage, malondialdehyde, total soluble sugars, proline and antioxidant enzymes activity content increased in more cultivars, significantly (p <0.01). Increasing drought stress to 25% field capacity, the highest and lowest leaf area decrease percentage compared to the control were observed in Copake Bogan (68%) and Gharashilig (45%) cultivars, respectively. Among the studied cultivars, the highest and lowest ion leakage content were observed in Aghshilig and Gharashilig cultivars, which had 36% and 32.8%, respectively. The highest proline content was obtained in Gharashilig cultivar (0.14 µmol g-1 FW) and the lowest was obtained in Copake Bogan cultivar (0.067 µmol g-1 FW). Also, The highest and lowest catalase enzyme content among the 6 studied grape cultivars were obtained in Gharashilig cultivar (3.02 µmol g-1 FW.min) and Copake Bogan (1.41 µmol g-1 FW.min). The highest peroxidase enzyme content was obtained in Tukilgen (5.86 µmol g-1 FW.min) and the lowest content in Rasmi (1.39 µmol g-1 FW.min) cultivar. The results showed, Aghshiligh and Copake Bogan cultivars were drought-sensitive and Garashiligh cultivars drought-tolerant and the rest are semi-drought sensitive cultivars.