Study On The Generality Of Wild Vetiver Grass Population In Western Guangdong Province

Vetiver(Vetiveria zizanioides) is an eminent tiller and has many uses. This paper researchon the growth,vegetative propagation,sexual reproduction,growing plasticity and densitydependent regulation in wild grassland and testing field, and find characteristic of populationand offer a theoretical guidance to "ecology engineering of vetiver". The results indicated:In August, the number of no jointing tillers of Vetiver population is 63.45% of total tillernumber in wild grassland. The biomass of jointing tillers and heading tillers is 78.8% of totaltiller biomass. In September, the number of white bud is 32.01% of total tiller number. ToDecember, the number and the biomass of white buds,no jointing tillers,jointing tillers andheading tillers reduced continuously. It means the sexual reproduction period has basicallyfinished and the number of each growth estate tillers held the line. From March to May of thenext year, the change of the number of tillers is inconspicuous.The increasing speed of the number of total tillers and no jointing tillers in wildgrassland is far more than that in testing field. The jointing tillers and heading tillers finishgrowth in wild grassland is earlier than that of in testing field by one month. In spring, youngtiller survival rate has been increased after cradled in winter at wild grassland. At the sametime, the cradle slowed the deposition of energy in spring, which delayed the jointing stageand heading period. The seeds production would be reduced.Because there is more than one ear per tiller, the number of ears was far more than thenumber of the heading tillers. The earring and fruiting rate was 11.56%. The number of thesprigs ,spikelets with stem and spikelets without stem were decreased by index function withthe nodes increase at 0.01 level, and were most at the basal ear of 21 nodes. The quantitativecharacter of the ear decreased most slowly with the nodes increase at the ear of 20 nodes. Thenumber of ear nodes was increased by linear function with the length of ear increase at 0.01levels. The number of sprigs on the ear was increased by power function with the length ofear increase at 0.01 levels. The number of spikelets with stem and spikelets without stem wereincreased by index function with the length of ear increase at 0.01 levels. The number ofspikelets with stem and spikelets without stem were increased by power function with thenumber of sprigs increase on the ear at 0.01 levels.The height of tiller and the number of laminas in wild grassland is significantly lowerthan that in testing field. There were not significant variations in the biomass of tiller,lamina,vagina and stem. The ecological plasticity of the quantitative character of vetiver in wildgrassland is bigger than that of testing field. The biomass of tiller,lamina,vagina and stemwere increased by index function with the height of tiller increase at 0.01 level. Theincreasing speed of biomass of tiller ,lamina,vagina and stem were higher in wild grasslandthan in testing field. The increasing speed on biomass allocation in stem and vagina washigher than lamina in wild grassland. Both the increased height and weight of tiller had stableregulation of allometron in two plots. The biomass of vagina and stem and lamina wereincreased by linear function with the biomass increase of tiller at 0.01 levels in both plots. Thecomparative growth of stem and leaf of tiller had stable regulation of allometron.The number of vetiver tillers that were planted in September was increased obviously inOctober and May of next year. The biggest density is 821 tillers per area, which density didnot restrain the increase of the tiller number. At the beginning of June, there was obviouslysignificant variations in the number of no jointing tiller,jointing tiller,heading tiller between80 tillers per area and other density spots. The biomass was increased by linear function withdensity at 0.05 levels. The number of no jointing tiller,jointing tiller, heading tillers, andtotal tiller were increased by power function with density at 0.01 level. The current densitydid not restrict growth of vetiver, but the increasing speed of tiller number has declinedobviously.