Effects Of Precipitation Regime,Nitrogen Deposition And Their Interaction On Trade-Off Between Sexual Reproduction And Vegetative Reproduction In Leymus Chinensis

Leymus chinensis(Trin.)is a typical perennial clonal grass species in Songnen plain of the Northeast of China,has high feeding valuable and drought-enduring,cold-resistant,and saline-alkaline tolerant.In recent years,phenomenon of global climate warming,precipitation rate changes and elevated nitrogen deposition is becoming more obvious as results from anthropic activities.As key factors limiting plant growth in semi-arid grassland,both nitrogen and moisture can affect plant growth in grassland.Trade-off between asexual and sexual reproduction is one of the key strategies adapting to environmental changes for clonal plants.Therefore,for better understanding the ecological adaption strategies under the background of global climate change,it is critical to explore the trade-off between asexual and sexual reproduction under precipitation rate change and elevated nitrogen deposition.This research as Leymus chinensis an experimental material to clarify the effects of precipitation regime and nitrogen deposition and their interaction on trade-off between Sexual Reproduction and Vegetative Reproduction by quantity the number of different module and each module's biomass in Leymus chinensis.The main results were as follows:(1)Under the treatments of increasing precipitation and precipitation with nitrogen addition,the rhizome and daughter shoot biomass of Leymus chinensis reached the highest.The number of daughter shoot and three types of daughter shoot also reached highest under this condition.Comparison between the inter-annual showed that under the condition of the interactions of high precipitation and nitrogen,the total number of daughter shoot increased significantly,and the daughter axillary rhizome shoot output was significantly reduced,the daughter axillary shoot output significantly increased.The daughter apical rhizome shoot changed was not significantly,the output number of differences between three types of daughter shoots showed that in the years of high precipitation and nitrogen interactions conditions happened to trade-off the relationship between three types of daughter shoots of Leymus chinensis.The high precipitation and nitrogen treatments number of axillary rhizome buds,and further increased the number of daughter axillary shoot,and suppressed the output of daughter axillary rhizome shoot.However,the effect of increasing nitrogen condition on the apical rhizome buds was greater than the precipitation changes.The axillary shoot buds was not significantly affected by the nitrogen and precipitation,which may be due to that more axillary shoot buds changeinto daughter axillary shoots.Nitrogen addition could significantly increase the spike biomass,and the high precipitation could decrease the spike biomass.Under the nitrogen and subtract precipitation conditions,the spike biomass of Leymus chinensis could achieve the optimal.The low precipitation could significantly increase the spike length.Whereas,nitrogen addition had no significantly influence on spike length of Leymus chinensis.The most of spikelet occurred at the treatment of adding nitrogen together with increase precipitation.Nitrogen addition significantly increased the number of florets and seeds number.Instead,changed in the precipitation was not significantly affected on the number of florets and seeds number of Leymus chinensis.Under the interactions of increased precipitation and nitrogen conditions,Leymus chinensis increased resource of rhizome and daughter shoot input on asexual reproduction.On the contrary,it decreased resource of spike input on sexual reproduction.Under high precipitation and nitrogen conditions,the reproduction countermeasure of Leymus chinensis was changed.Both sexual reproduction and asexual reproduction had the trade-off relationship.(2)The total biomass and leaf biomass could significantly increased with the precipitation and increased nitrogen.The changes of precipitation could significantly affect the stem biomass.However,the nitrogen fertilization had no effect on the stem biomass.Precipitation had no effect on the root biomass and nitrogen fertilization could increase the root biomass.Under the treatment of high precipitation with nitrogen addition,the total and leaf biomass was significantly increased.However,the stem biomass and root biomass were only influenced by the single treatment of precipitation or nitrogen.The increased precipitation and the interactions with nitrogen fertilization significantly increased the percentage of leaves to total biomass.Under such conditions,the leaves and stems occurs a trade-off relationship,made the resource input to the leaf and lead a decrease in stems biomass.However,different treatment had no significant effect on the resource input to roots in Leymus chinensis.