Abstract:

【Objective】 This study is to examine the effects of light intensity and fertilization on the growth of Poa crymophila in Alpine meadow and to provide insights into the proper utilization and the optimal management of the meadow. 【Method】 Through a factorial design in field, the experiment included eighteen 1.3 × 0.8 m plots with a total of 6 treatment combinations of light and fertilization. The intensity of light was divided into three levels: 100% of light (strong), 43.5% of light (medium) and 6.74% of light (weak). The treatment of fertilization included two levels: fertilized and non-fertilized. The parameters of plant growth (tiller numbers, plant height, above-ground biomass, specific leaf area, relative growth rate and the resource allocations to different plant parts) were measured to assess the adaptation of this herb to dissimilar circumstances. 【Result】 The results showed that the number of tiller and above-ground biomass of P. crymophila decreased as the light reduced, which could be compensated by fertilization. The plant reached its maximum of height under the medium intensity of light. The fertilization promoted the growth of plant under the strong and weak intensity of light. When the light weakened, the SLA increased but the RGR reduced, while fertilization had no effects on them at all. Root allocation and root/shoot ratio had no significant difference between treatments under medium and weak intensity of light respectively, but the fertilization could lead to the decrease of root allocation and root/shoot ratio under the strong light. When the intensity of light reduced, the leaf allocation increased while the reproduction allocation reduced, while fertilization had no influence on the leaf and the reproduction allocation. The stem allocation decreased with the reduced intensity of light under the fertilization treatment. Under the non-fertilized treatment, the stem allocation was the largest under the medium light treatment rather than the strong and the weak light intensity. 【Conclusion】 P. crymophila is sensitive to light as the decrease of light has an negative effect on its growth. The strong light and the fertilization can benefit the plant growth, while the medium light can weaken the effect of fertilization, and the negative effect of weak light can be compensated by the fertilization treatment. For the grassland under canopy dominated by P. crymophila, the fertilization is ineffective when the light intensity permeated through the gap of canopy can reach the medium level; however, if it achieves the low light level, the grass production can be increased by fertilization.

Key words: light, fertilization, tiller number, aboveground biomass, specific leaf area, Poa crymophila