| The seedlings of alfalfa were treated with CoCl2 to determine its optimal concentration to improve the growth of alfalfa under drought stress condition. The results showed that when the concentration was 0.000250.1 mmol/L, the plant height, number of branches, root length, leaf area, fresh weight of above-ground part, fresh weight of under-ground part, dry weight of above-ground part and dry weight of under-ground part were all increased to some degree, and most of the parameters were optimal at the concentration 0.005 mmol/L. It was proved that low concentration of CoCl2 was beneficial to the growth of alfalfa seedlings, but high concentration resulted in some injury effects. The relationship between plant height (y) and leaf area (x1), number of branches(x2), fresh weight of under-ground part(x3), dry weight of above-ground part(x4), root length(x5), fresh weight of above-ground part(x6), dry weight of under-ground part(x7) could be described by the multivariate linear regression equation: y=2.9153-0.4377x1+0.1227x2-4.9510x3-3.0736x4+226.4584x5+350.9114x6+342.4854x7. |