The Effects Of Ear Removed At Different Reproductive Stages On Photosynthetic Physiology,yield And Quality Of Leymus Chinensis

Songnen grassland plays an important role in the development of animal husbandry in northeast China.In recent years,the grassland in this area has been continuously degraded,resulting in a rapid decline in forage yield and quality.As a constructive species of Songnen grassland,Leymus chinensis,not only has bio-ecological characteristics such as drought tolerance,cold tolerance and saline-alkali tolerance,but also has high feeding value.Therefore,the yield and quality of Leymus chinensis is very important for the development of grassland animal husbandry in this area.Leymus chinensiswas taken as the research object,and the effects of ear removal at different reproductive stages on photosynthetic characteristics,carbon and nitrogen content,growth and forage yield,and quality on Leymus chinensis were studied in artificial grassland and natural grassland respectively in Songnen grassland.The aim is to provide theoretical basis for scientific management and production of Leymus chinensis grassland in this area.The conclusions are as follows:（1）In artificial grassland and natural grassland,the net photosynthetic rate,stomatal conductance,transpiration rate,intercellular CO₂ concentration and water vapor pressure deficit of Leymus chinensis were significantly improved by ear removal at different reproductive stages.This indicatedthat ear removal relatively improved the photosynthetic efficiency of Leymus chinensis,but had no significant effect on the leaf area index and chlorophyll content of the two grasslands.（2）In artificial grassland and natural grassland,the nitrogen content of Leymus chinensis was significantly increased by ear removal at the stages of milky ripeness and wax repeness.Compared with the treatment without ear removal,the nitrogen content of artificial grassland increased by 9%and 16%,and that of natural grassland increased by 20%and 32%respectively.Ear removal at different reproductive stages only significantly affected the carbon content of Leymus chinensis in natural grassland,and ear removal significantly reduced the carbon-nitrogen ratio of the two grasslands at the stages of milkky repeness and wax ripeness.（3）Ear removal at different reproductive stages tends to increase the agronomic characters and aboveground biomass of Leymus chinensis in artificial grassland and natural grassland,but the difference is not significant.However,it can significantly increase the underground biomass of Leymus chinensis in heading stage.（4）The crude protein content and crude fat content of Leymus chinensis in artificial grassland and natural grassland were significantly increased by ear removal at different reproductive stages.Compared with non-ear removal treatment,the crude protein content of Leymus chinensis at wax ripeness stage was increased by 26%and 22%,respectively.At the same time,the crude fiber,crude ash,neutral washing fiber and acidic washing fiber were all the minimum values during this period,which indicated that the feed quality of Leymus chinensis was the best after ear removal.In summary,ear removal at different reproductive stages promoted the vegetative growth and improved the quality of Leymus chinensis by adjusting the nitrogen distribution.The aboveground biomass and quality of the two grasslands reached the maximum at the wax ripenessstage of seed maturity,which was the best period for ear removal.