Abstract: Medicago falcata possesses an abundantly diverse array of phenotypic traits, which are influenced by habitat, and so are correlated with climatic gradients linked to altitude, latitude and longitude. This research aimed to characterise the genetic variation in M. falcata through study of correlation between the phenotypic characters of M. falcata and altitude. In this experiment, M. falcata (Variety Xinjiang) was used as the study material, and 18 phenotypic traits were studied, including plant height, number of branches, leaves, stems and flowers under the same latitude and longitude (N 43°43', E 86°94') over an altitude range of 2100-2350 m. These data provide a basis data for further research on genetic diversity and germplasm development in M. falcata. It was found that phenotypic traits are most variable with change in altitude. Plant height, leaf length, leaf width, internode length, stem diameter and floret length within inflorescences showed a trajectory across the altitude gradient of “declining-rising-declining” with decreasing altitude, with peak values at 2150 m of altitude. The values obtained for the phenotypic index ranged from 1.30%-22.83%, and the average coefficient of variation was 8.49%. There was a significant correlation between altitude and plant height, inflorescence length, petal length and keel width, with correlation coefficients of 0.490, 0.601, -0.449 and -0.421, respectively. Other phenotypic traits of M. falcata showed no significant correlation with altitude, and considering the data as a whole, an altitude of 2150 m is best suited for growth of M. falcata.

Key words: Medicago falcate, altitude, phenotypic traits, variation