Effects Of Water And Fertilizer Coupling On Yield,quality And Root Physiological Characteristics Of Alfalfa Artificial Grassland In Horqin Sandy Land

Aruhorqin banner,Chifeng City,Inner Mongolia is the main planting area of Alfalfa in China,which is of great significance to the development of animal husbandry in the north.However,the low level of water and fertilizer management has a great impact on the local alfalfa production,which limits the sustainable development of grassland and animal husbandry in this region.In view of the above situation,four irrigation levels(526,587,651,747 mm)and five fertilization levels(0,225,450,675,900 kg/hm~2)were set in this study.Through the measurement of yield,nutritional quality and root physiological characteristics,the effects of water and fertilizer coupling on Alfalfa yield,quality and root physiological characteristics in Horqin sandy land were discussed,so as to provide basis for water and fertilizer management of Alfalfa artificial grassland in Horqin sandy land.The results show that:1.with the increase of irrigation amount,the first and second crop yield and total yield of Alfalfa first increased and then decreased,and the yield was the largest under W2irrigation.With the increase of fertilizer application,the first crop yield,the second crop yield and the total yield of Alfalfa increased gradually.Under the coupling effect of water and fertilizer,the first crop yield,the second crop yield and the total yield of alfalfa were the largest under W2F3 treatment,which were 5716.84,6492.36 and 15148.48 kg/hm~2respectively.At this time,the irrigation amount was 587 mm and the fertilization amount was 450 kg/hm~2.2.the coupling effects of irrigation,fertilization and water and fertilizer had significant effects on irrigation water use efficiency and fertilizer partial productivity of Alfalfa(P<0.01);With the increase of irrigation amount,irrigation water use efficiency and fertilizer partial productivity of Alfalfa increased first and then decreased;With the increase of fertilizer application,the irrigation water use efficiency of Alfalfa gradually increased and then tended to be stable,and the fertilizer partial productivity decreased significantly.Under the coupling effect of water and fertilizer,the irrigation water use efficiency was the highest under W2F3 treatment,and its value was 25.81 kg/(mm·hm~2).At this time,the irrigation amount was 587 mm and the fertilization amount was 450kg/hm~2;The partial productivity of fertilizer is the largest under W2F2 treatment,and its value is 60.08 kg/kg.At this time,the irrigation amount is 587 mm and the fertilization amount is 225 kg/hm~2.3.irrigation treatment had a significant effect on the crude protein content of the third crop of Alfalfa(P<0.01).With the increase of irrigation amount,the crude protein content of the third crop of Alfalfa decreased.Fertilization had a significant effect on the crude protein content of each crop of Alfalfa(P<0.05).Increasing the amount of fertilization could increase the crude protein content of each crop;The coupling effect of water and fertilizer had a significant effect on the crude protein content of the second crop of Alfalfa(P<0.01).The crude protein content of the second crop of alfalfa was the highest under W2F3 treatment,and its value was 20.72%.4.with the increase of irrigation amount,the soluble sugar content in alfalfa roots decreased significantly(P<0.05),soluble protein content,free amino acid content,POD activity and CAT activity increased first and then decreased,MDA content decreased first and then increased,and there was no significant difference in the changes of starch content and SOD activity(P<0.05).Fertilization could significantly increase the soluble protein content and POD activity of alfalfa roots(P;With the increase of fertilizer application,the activities of SOD and cat increased gradually,and the content of MDA decreased first and then increased.The comprehensive evaluation of cold resistance of physiological indexes related to cold resistance in roots under different water and fertilizer coupling was carried out by using principal component analysis.The results showed that the cold resistance of Alfalfa under W3F2 and W2F3 treatment was the largest and the cold resistance was strong.