Physiological and biochemical changes of Alfalfa (Medicago sativa L.) cultivars at different growth stages

Physio-biochemical changes in plants are a principal practice to manage harvesting time. the present study was aimed to investigate the effect of flowering stages (10%, 50%, and 100% flowering) on physiological and biochemical properties in four cultivars of three- and four-year-old alfalfa (medicago sativa l.) plants (fasta, hamadani, meldor, and sovrana) based on a randomized completely block design (rcbd). results showed that four-year-old plants of hamadani cultivar had higher total phenolic content (tpc) and total flavonoid content (tfc) at middle flowering stages. catalase (cat) and superoxide dismutase (sod) activities increased by progressing the flowering stage and time of harvesting. proline content increased by advancing the flowering stage as its highest level was observed at late flowering stage in fasta cultivar. middle flowering stage (50% flowering) represented the greater chlorophyll (chl.) content compared with early and late maturity. relative water content (rwc) decreased by progressing the maturity as its highest level was observed at early flowering stage. rwc differed from 65% in four-year-old plants of sovrana at late flowering stage to 80% in three-year-old plants of meldor cultivar at early flowering stage. malondialdehyde (mda) content and total soluble sugar (tss) increased by advancing the maturity. four-year-old sovrana plants at late flowering stage contained higher mda and tss. heat map analysis showed the significant role of all physiological and biochemical traits except total chl. for clustering the cultivars. the study recommends hamadani cultivar because of high phenolic compounds and the minimum variations in biochemical properties at year four.