Effects of Water Stress on some Physiological Characters in Four Varieties of Alfalfa (Medicago sativa L.)

Abstract

Four different varieties of alfalfa (Medicago sativa L) were used to evaluate the effects of water stress on its physiological performance. These were Higazi, Srivir, Pioneer and Cuf 101. The experiment was conducted during the period February to July of 2011. A factorial experiment using a randomized complete block design with four replications was used to layout a pot experiment at the Nursery of Desertification Research Institute, National Center for Research. Four levels of water stress treatments using water interval as indicator. These were: two days, five days, ten days and fifteen days intervals between any two irrigations. The study was divided into two growth stages; before and after subjecting to water stress. Before subjecting to water stress, the plants were irrigated every two days. Data were collected on dry matter (%), protein content (%), chlorophyll content (mg/100g) and total available sugars (CHO %). Data were collected three times before water stress. These were: stage of emergence the third leaf (K1), 45 days after sowing (K2) and 70 days after sowing (K3). After subjecting to water stress the data were collected four times. These were 15 days (K4), 30 days (K5), 45 days (K6) and 60 days (K7). Before starting treatments, highly significant differences were revealed for protein content, chlorophyll content and CHO among varieties in the three stages of growth (K1, K2 and K3). After starting water stress treatments, most varieties of alfalfa showed tolerant under five and ten days intervals of watering treatments (W2 and W3, respectively). Higazi and Srivir were tolerant to drought conditions compared to the other ones. Hegazi was superior for CHO under five days (W2) and protein content under ten days (W3), whereas Srivir outscored for CHO under W3. Cuf 101 was superior for chlorophyll content under ten days (W3) and dry matter under W2 and W3. Pioneer outscored for protein content under two days (W1)