Plasticity Of Growth And Production Of Chloris Virgata Reproductive Tillers On Different Sowing Dates In Songnen Plain

Chloris virgata is a tuft annual grass of Gramineae,The plant distributes widely in the degraded plains and saline meadows.Its growth period is short,and seeds germinate from spring to summer and it can complete the entire life cycle.Effect of different sowing time on growth and seed production of C.virgata reproductive tillers is of vital significance for theoretical and practical research.By experiment and measurement in plot with different sowing time in two years,characters of plasticity and regularity of growth,seed production,biomass allocation were analyzed in this paper.Based on the study,it could be provided for the accumulation of theories and research methods of plant reproductive ecology.The main findings are as follows:1.The number of reproductive tillers of C.virgata with different sowing time in two years had strong phenotypic plasticity.With the delay of sowing time,tiller height,inflorescence length,tiller biomass,inflorescence biomass and inflorescence branch decreased,reproductive growth ratio and reproductive allocation increased.Reproductive growth ratio of the third sowing(13 June)were significantly greater than the first sowing(25 May),reproductive allocation was similarly regular.One thousand-seed weight among the first three sowing was not significantly different,the fourth seeding(24 June)decreased significantly,but also significantly increased in the fifth seeding(3 July).Seed rate of five sowings remained at a high level,and the difference was not significant in 2014;the highest rate of seed came from the first sowing(25 May),and fourth seeded significantly reduced(24 June).2.For the same sowing time in two years,with the mature time delay,tiller height,inflorescence length,tiller biomass,inflorescence biomass and inflorescence branch decreased,but reproductive growth ratio and reproductive allocation increased.For delayed maturity time of 16 days tiller height in the first sowing was significantly decreased by 8.1% in 2014,and for delayed maturity time of 4 days tiller height was significantly decreased by 10.1% in 2015.With the delay of mature time,one thousand-seed weight of five sowing times significantly decreased sequentially in two years.One thousand-seed weight decreased by 30.4%,29.9%,23.2%,20.3%,18.1% in 2014 and decreased by 19.2%,32.1%,21.1%,18.8%,16.9% in 2015.Although seed rates were affected by mature time,it was not significantly different.3.The same mature time in two years,with the increasing sowing time delayed,tiller height,inflorescence length,tiller biomass,inflorescence biomass and inflorescence branch decreased,but reproductive growth ratio and reproductive allocation increased,Onethousand-seed weight fluctuated irregularly.When mature time delayed 22 days,seed rate of the fouth sowing(24 June)was significantly decreased by 7.9% in 2014,seed rate of other mature time declined slightly,but it was not significant.The growth time of tillers reduced because of delayed sowing.For the same delayed mature time,tillers of delayed sowing were not good to the growth of module,but one thousand-seed weight and seed rate were still able to maintain at a stable level.4.The comparing results of two years,about the number of reproductive tillers of C.virgata during five sowing time,were not consistent.Except for the second sowing(4 June),tiller height of other fourth sowings was higher in 2015 than the same period in 2014.One thousand-seed weight of all five sowings was higher in 2015 than the same period in 2014,sowing of four were significant different.Seed date of all five sowings was lower in 2015 than the same period in 2014,all of them was significant different.5.Reproductive allocation was significant negatively correlated to seed rate,tiller height,inflorescence length,tiller biomass and inflorescence biomass(P<0.05)in two years.The best-fit model that described the relationships between reproductive allocation and seed rate,inflorescence length,tiller biomass was linear.There was an exponential correlation between the reproductive allocation and tiller height,inflorescence biomass.In 2014,a value,the fitting equation parameter,of reproductive allocation and seed rate decreased by about 77.1%,and b value of the equation decreased by about 80.5%,a value of reproductive allocation and tiller biomass decreased by about 7.8% and b value of the equation decreased by about 46.2%,a value of reproductive allocation and inflorescence length increased by about 21.9% and b value of the equation increased by about 36.6%.In addition to seed rate and inflorescence length were not correlated significantly in 2015,seed rate was a significant positively correlated to tiller height,inflorescence length,tiller biomass,inflorescence biomass(P<0.05)in two years,and seed rate was significantly correlated to tiller height,inflorescence length,inflorescence biomass(P<0.01)in 2014.