Payame Noor University, Karaj Center, Iran
As a perennial forage crop, alfalfa can be cultivated in marginal lands and has a high yield and good quality high-protein content. In Iran alfalfa is the main forage crop and is grown on about 618,000ha, where summer drought is relatively severe and sometimes alleviated by irrigation. In order to study the response of 10 different perennial ecotypes of alfalfa to water deficit at germination stage, an experiment was conducted in a controlled environment. The experiment was performed as a factorial, randomised complete block design with three replications. In this research the effect of six levels of osmotic potential (0, -4, -6, -8, -10 and -12 bar) resulting from polyethylene glycol 6000 were investigated on germination index of ten different perennial alfalfa ecotypes including six Iranian ecotypes (Gharah yonje, Hamedani, Farahane Arak, Synthetic Karaj, Mohajeran Karaj and Shorkat) and four foreigner ecotypes (Harp, Jolia, Deft and Dian). The following traits were measured: germination rate and percent, root and shoot lengths, seedling dry weight, and root to shoot dry weight ratio.
Analysis of variance showed that water deficit influenced all seed germination traits of alfalfa (p < 0.01). Also, there were significant differences among ecotypes for above-mentioned traits. In general there were not significant differences among ecotypes for seed germination traits at water deficit up to -4 bar. Root and shoot length and root and shoot weight of alfalfa seedlings increased with increasing water deficit up to -4 bar which resulted in seedling dry weight increase. Root to shoot dry weight ratio also increased in water deficit up to -4 bar. In high water deficit (between -6 and -8 bar) all above"=mentioned traits were severely decreased.
Keywords: Alfalfa, germination, Medicago sativa, seedling growth, water deficit