Study of some morphological traits and selection of drought-resistant alfalfa cultivars (Medicago sativa L.) in Jiroft, Iran

In order to determine the effects of water deficit stress on some morphological traits of alfalfa cultivars in Jiroft, Iran, an experiment was conducted in the fields of Agricultural Research Center of Jiroft in 2005-2006. It was a split-plot experiment based on a Randomized Complete Block Design with three replications, in which water deficit stress at three levels [including severe stress (irrigation when soil moisture was 25% of field capacity), moderate stress (irrigation when soil moisture was 50% of field capacity) and mild stress (irrigation when soil moisture was 75% of field capacity)] made the main plot and alfalfa cultivars at five levels (Yazdi, Nikshahri, Ranger, Bami and Baghdadi) made the sub-plot. The results of six sequential cuttings showed that water deficit stress significantly affected all morphological traits except internode length. The effect of cultivar was significant at 1% level on all traits except leaf/stem ratio and node number. With the increase in the intensity of drought stress, fresh forage yield, dry forage yield, stem length, stem number/unit area, leaf area index, internode length and internode number decreased but leaf/stem ratio increased. Dry forage had the highest correlation with plant height, stem number/unit area and leaf area index. Leaf/stem ratio had a negative correlation with forage yield. Finally, the cultivars Nikshahri and Bami were selected as drought-resistant cultivars, Baghdadi and Yazdi were selected as semi-drought-resistant cultivars and Ranger was selected as drought-sensitive cultivar in the region.