Harvest Time and Cultivar Effects on Growth, Physiological Traits, Yield and Quality of Alfalfa in Saline Condition

One of the most important forage crops in Iran is Alfalfa ( Medicago sativa L.). Cultivar selection is important for alfalfa hay production. This research was carried out in 2017 and 2018 to assess the effects of harvest time and cultivar on growth, physiological traits and yield of alfalfa in saline condition. These field experiments were carried out at the Research Farm of East-Azarbaijan Agricultural and Natural Resources Research and Education Center, Tabriz, Iran (Firuz Salar village located 4 km from Azarshahr city). Results showed that the synthetic cultivars (C 2 and C 3 ) and especially C 4 (Azar cultivar) has the highest forage yield and it attributed to high chlorophyll content, catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) activities, proline content, leaf area index (LAI), stem diameter, plant height and leaf to shoot ratio in these cultivars. However, the highest malondialdehyde (MDA) content related to C 1 cultivar (Gara-Yonjeh as a local cultivar). Maximum of fresh and dry forage yields were achieved in second and third harvest times and it have related to high chlorophyll content, enzyme activities (CAT, POD and SOD), LAI, stem diameter, plant height, leaf to shoot ratio, proline and MDA contents in these harvest times. The highest acid detergent fiber (ADF), neutral detergent fiber (NDF), protein content and digestibility were obtained from C 4 followed by C 3 , C 2 and C 1 cultivars. Value of ADF, NDF, protein content and digestibility were more during early harvests (H 1 and H 2 ) than during last harvests (H 3 and H 4 ). These findings have shown that suitable harvesting time of forage alfalfa is second stage for high yield and first stage for high quality. Synthetic cultivars and especially Azar cultivar was a superior cultivar. Thus, harvest time and cultivar selections can influence the yield and quality of alfalfa.