Effects Of Cutting On The Yield, Quality And Overwintering Ability Of Alfalfa

Due to the characteristics of high yield, strong resistance, high quality, good palatability and strong adaptability, alfalfa is well known as "the king of the grass" and plays a crucial role in the development of forage husbandry. Different cutting ways have an important influence on the reproducibility, quality and overwinter ability of alfalfa. In order to have a good understand on the dynamic variation regularity of yield and nutrition, explore the best way of cutting and provide guidance for the production of alfalfa in the northeast of China. In this research, Medicago sativa L. cv. Zhaodong that has grown for 12 years was selected, and the effect of cutting on alfalfa yield, the content of CP, NDF and ADF as well as overwinter rates was studied. The results were showed as follows:(1) For alfalfa in different growth periods, there were significant difference in the growth speed, yield and quality(P < 0.05). With the growth and development of alfalfa, its growth speed presented a tendency as increased in the primary period and then reduced, the ratio of straw and leaf increased and the ratio of fresh weight and dry weight reduced; both fresh weight and hay yield increased in the primary period and then reduced with reaching the maximum on July 2nd, the content of CP reduced while the content of NDF and ADF increased. Therefore, in order to get alfalfa with high yield and quality in the western of Jilin province, alfalfa should be cut early.(2) There was significant influence for cutting alfalfa in different growth periods on the regrowth speed and yield of alfalfa(P < 0.05). With the times of cutting increasing, the regrowth speed of alfalfa reduced and the regeneration ability became weak. In the same cutting period, the yield became reduced with the increasing of cutting times. When alfalfa was cut in the vegetative period, its yield in the second cutting was the highest, as 2.04 t hm-2. The order of total annual hay yield was: early flowering period(10.26 t hm-2) > squaring period(9.74 t hm-2) > vegetative period(6.97 t hm-2). There was no significant difference in total annual hay yield between early flowering period and squaring period, but the difference between early flowering period and vegetative period was significant. Therefore, the best cutting period to gain high yield is between squaring period and early flowering period.(3) Different cutting ways had significant effects on the quality of alfalfa(P < 0.05). When alfalfa was cut in the vegetative period, the content of CP was the highest and the NDF, ADF content were the lowest. Hence, the quality of alfalfa cut in the vegetative period was the best, that in the squaring period was lower, and that in the blooming period was the worst. When alfalfa was cut in the vegetative period, the quality of alfalfa was reduced with the increasing of cutting times. While when alfalfa was cut in the squaring period and early flowering period, there was no significant difference in the alfalfa quality in different cutting times.(4) There was significant influence for different cutting ways on the injured degree of alfalfa in the next year(P < 0.05). When alfalfa was cut in the squaring period and early flowering period, alfalfa could be cut for three times in the western of Jilin Province and all the alfalfa could overwinter safely. While when alfalfa was cut in the vegetative period, alfalfa could be cut for five times in the western of Jilin Province, but the growth of alfalfa in the next year was injured in different degrees and was significantly different from that in the squaring period and early flowering period. Therefore, in order to guarantee alfalfa to overwinter safely and be utilized sustainably, alfalfa in the western of Jilin province should be harvested less than 5 times per year.