Effects of growth stage on yield and quality of leaf and stem

In order to get the optimal harvest period of alfalfa, three varieties Guanzhong alfalfa, Algonquin and Gold Empress were harvested at budding stage, early blooming, full booming, pod setting stage and maturing stage, respectively. Their stems and leaves were separated and dried, yield, stem to leaf ratio, plant height, branches and nutritional characteristics were measured. The results showed that, along with the growth of alfalfa, yield increased then decreased, yield were highest at pod setting stage. Stem to leaf ratio was higher than other periods at budding stage, but plant height and branches were the highest at maturing stage. Along with the growth period delaying, crude protein, crude fat and relative feeding value gradually decreased, crude fiber, neutral detergent fiber and acid detergent fiber gradually increased. Crude protein and relative feeding value at budding stage were significantly(P<0.05) higher than that of early blooming, full booming, pod setting stage and maturing stage; In leaves and stems, compared with the latter, crude protein increased by 4.52%, 8.28%, 12.06%, 14.70% and 12.59%, 9.38%, 11.19%, 28.18%, respectively; compared with the latter, relative feeding value increased by 6.55%, 6.60%, 29.07%, 40.25% and 3.84%, 6.09%, 4.88%, 10.99%, respectively; compared with the latter, crude fiber decreased by 29.88%, 20.19%, 20.98%, 3.31% and 3.81%, 0.70%, 1.92%, 1.04%, respectively. Budding stage was the best stage of cutting.