بررسی تأثیر کم‌آبیاری بر صفات مورفولوژیک و تولید ارقام مختلف یونجه در شرایط آب‌ و ‌هوایی خوزستان - اهواز

In order to investigate the effect of water deficit on yield and morphological characteristics of four alfalfa cultivars an experiment was conducted as a split plot in randomized complete block design with 3 replications in Agriculture Research Center of Khuzestan, Ahwaz, Iran, during 201l-2012. Main plots included irrigation regimes (normal irrigation, irrigation at 50% available water content (AWC) depletion, 65% AWC depletion and 80% AWC depletion) and subplots were 4 cultivars of alfalfa (Baghdadi, Mesasirsa, Yazdi and Hamedani). The result of 5 cuttings showed that maximum hay forage yield was achieved under normal irrigation in all cultivars. The Baghdadi cultivar produced the highest hay yield at all irrigation treatments, though the hay yield decreased with delay in irrigation. The leaf/stem ratio increased by 22 percent when the cultivars where subjected to 50% AWC depletion. Stem height, LAI and the weight of single stem were decreased by delay in irrigation. Specific leaf area (SLA) decreased in all cultivars due to water deficit, though the extent of the decrease was greater for Baghdadi cultivar. The water deficit affected stem number in a cultivar-specific manner as it increased in Baghdadi and Mesasirsa cultivars and decreased in other cultivars. The Baghdadi and Mesasirsa appeared to be the most tolerant cultivars in Khuzestan conditions.