Effects Of Delayed Heading On Population Reproduction Of Four Common Steppe Plants

In the alkaline meadow of the Songnen Plain in Northeast China,the populations of Puccinellia tenuiflora,Chloris virgata,Hordeum brevisubulatum and Leymus chinensis are widely distributed,and all of them can form a single dominant species community under the habitat conditions of the alkaline patch,which has important scientific significance for the management and improvement of the saline-alkali meadow.Due to the difference of individual development time or growth location in clonal plant population,the plant size is different.At the same time,the flowering period usually has a certain time range,and the time to enter the reproductive growth stage is different.This study on the grass,of Puccinellia tenuiflora,Chloris virgata,Hordeum brevisubulatum and Leymus chinensis population reproductive tillers strains under different reproductive growth time used in the determination of a large sample of random markers and sampling,analysis and comparison to extend the time of reproductive growth of reproductive tillers of plasticity and the change law of growth of clonal plants and distribution strategies which provide scientific and rational utilization of grassland.The main results are as follows:The maximum variation coefficients of Puccinellia tenuiflora of tiller height and inflorescence length were 19.835% and 23.408% when reproduction was prolonged for 1 day and 5 days,respectively.The variation coefficients of tiller weight and inflorescence weight were 40.198% and 54.845% at 17 days of prolongation.The maximum variation coefficients of Chloris virgata of tiller height and inflorescence length were 15.43% and 16.208% at prolongation of reproduction for 4 days and 1day,respectively.The maximum variation coefficients of tiller weight and inflorescence weight were 32.812% and 41.198% when reproduction was prolonged for 4 days and 1 day,respectively.The variation coefficients of Hordeum brevisubulatum of tiller weight and inflorescence weight of wild barley were22.591% and 28.196% at 5 and 9 days of prolongation,respectively.The highest variation coefficients of Leymus chinensis of tiller height and inflorescence length were 17.082% and 24.796% at prolongation 13 and 1 day,respectively.The variation coefficients of tiller weight and inflorescence weight were the highest at 17 and 1 day,respectively,reaching 32.847% and 43.763%.This experiment through Puccinellia tenuiflora,Chloris virgata,Hordeum brevisubulatum and Leymus chinensis population reproductive tillers of the variation coefficient of each target is found that under the condition of the extension of the reproductive growth,inflorescence length plasticity were greater than its tiller height,biomass plasticity were greater than the tiller height and inflorescence length,and inflorescence weight plasticity were greater than tiller weight;The number of florets,seed number,seed weight and seed setting rate had strong plasticity.Reproductive allocation ? plasticity are the largest.The plasticity of reproductive growth ratio of Leymus chinensis was strong,but that of Puccinellia tenuiflora and Chloris virgata was weak.As the extension of reproductive time,Puccinellia tenuiflora of tiller height and reproductive allocation ? linearly increased;The reproductive growth rate decreased linearly.Inflorescence length,tiller weight,inflorescence weight,floret number,seed number,seed weight,thousand-grain weight,reproductive allocation ? and seed setting rate were increased exponentially;The reproductive allocation ? increase power function.As the extension of reproductive growth time,Chloris virgata of tiller height,floret number,seed number,seed weight,thousand-grain weight,reproductive allocation ?,reproductive allocation ? and reproductive allocation ?linearly increased;tiller weight and inflorescence weight increased by power function.Inflorescence length and seed setting rate increased exponentially.The reproductive growth rate decreased exponentially.Hordeum brevisubulatum of tiller weight,floret number,thousand-grain weight and reproductive allocation ? linearly increased;inflorescence weight,seed number,seed weight,reproductive allocation ?,reproductive allocation ? and seed setting rate linearly increased.Leymus chinensis of tiller height,inflorescence length,tiller weight,inflorescence weight,floret number,seed number,seed weight,thousand-grain weight,reproductive allocation ?,reproductive allocation ?,reproductive allocation ? and reproductive growth rate linearly increased;Seed setting rate increases as a power function.It was found that with the prolongation of reproductive time,the growth rules of tiller height and inflorescence length were the same,but the biomass accumulation rules were different.The variation of seed setting rate of reproductive tillers of Puccinellia tenuiflora,Chloris virgata and Hordeum brevisubulatum was the same,but the variation of reproductive distribution was different.The reproductive growth ratio of Puccinellia tenuiflora and Chloris virgata decreased gradually,but that of Leymus chinensis increased.In conclusion,under prolonged reproductive conditions,the growth and biomass plasticity of reproductive tillers in the populations of Puccinellia tenuiflora,Chloris virgata,Hordeum brevisubulatum and Leymus chinensis are strong.With the prolongation of reproductive growth time,the variation rules of reproductive quantity characteristics of the four species populations are similar and different.