| Chloris virgata is a fast-growing annual plant with strong alkali-tolerance.It is a pioneer species of grassland restoration succession and can form a single dominant community on alkalized meadows.C.virgata can complete the entire life history when germinating from the beginning to the middle-late in the growing season.The study on the plasticity and regularity in the growth of C.virgata clones and modules at different sowing time can provide scientific accumulation for intensive study of population regulation in annual plants,and it can also provide scientific basis for utilization and management of alkalized grassland.In this paper,a quantitative analysis of plasticity and variability in growth period,size and of module growth,the ralationships between quantitative characteristics of reproductive growth,root biomass allocation,and growth time at different sowing date were conducted by planting regularly in the plot.The main results are as follows:1.In seeding experiments,the earlier sowing,the longer growth period C.virgata was at different time in two years,which was 104 days in 2016 and 101 days in 2017;the growth period was the shortest in latest seeding time,which was 61 days and 54 days,respectively.As the sowing time was delayed,the vegetative period is shorter than the reproductive period.It revealed that the growth period of C.virgata had stronger phenotypic plasticity,and the time of vegetative growth was mainly used to ensure seed setting and seed ripening time.2.As the sowing time was delayed,the bunch diameter of C.virgata clones was the largest on the second sowing in two years,an average of 8.72 cm in 2016 and 17.52 cm in 2017;the bunch diameter was the smallest on the last sowing,which was 1.75 cm and 1.25 cm respectively.The number and biomass of both vegetative tillers and reproductive tillers,of C.virgata decreased gradually with the delay of sowing time in two different years;the heading rate reached the maximum at the last sowing,reaching 93.56% in 2016 and totally 100% in 2017.The quantitative characteristics of growth and production in C.virgata clones in 2017 were significantly higher(P<0.05)than that of 2016.It revealed that there was greater plasticity in growth of clones and their modules among the sowing times and between the two years.3.The inflorescences biomass in C.virgata reproductive tillers was the largest on the second sowing time in two years.Among them,the highest was 0.6335±0.0821 g in 2016 and 0.6319±0.1086 g in 2017.The smallest was 0.2593±0.0653 g and 0.2978±0.639 g,respectively,in the last sowing.The quantitative characteristics of reproductive tillers in 2017 were all higher than that in 2016,and most of them was significantly different(P<0.05).4.The root system of C.virgata clones also had greater plasticity at different sowing time.The longest root length and the largest root volume were observed at the second sowing time in two years,including 37.43 m and 5.54cm3 in 2016 and 109.01 m and 9.98cm3 in 2017;the shortest root length and the smallest root volume were found at the last sowing time,0.61 m and 0.01cm3,0.88 m and 0.02cm3,respectively.Compared with the first sowing,the root surface area reduced significantly at the third sowing(P<0.05).5.The quantitative characteristics of clones and their growth periods showed different regularities.There was a significant negatively linear correlation between tillers height,reproductive growth ratio and the growth time in two years(P<0.05);inflorescence length,inflorescence branch,reproductive allocation,one thousand-seed weight,and seed-setting rate were all conic functions and reached significant or extremely significant level.However,the root biomass allocation did not show a consistent regularities in two years.The root biomass first increased gradually and then decreased in conic in 2016,and increased in conic in 2017,and all reached extremely significant levels(P<0.01). |
PDF Full Text Request