栽培密度对薄荷生长策略和光合特性的影响

比较研究了不同栽培密度对薄荷生长策略及光合特性的影响。结果表明：（1）随着密度的升高，单株的株高、茎粗、分枝数、单叶面积、叶片厚度等下降；（2）提高栽培密度时，薄荷的光合色素含量、光合面积、净光合速率均降低，而PSII的最大光化学效率不变；（3）高密度下，单株的根、茎、叶及总生物量积累下降，而群体的生物量积累变化不明显，但地下部分的生物量分配比例均显著增加。进一步分析表明密植会通过降低薄荷单位面积的色素含量而导致光合速率下降：栽培密度提高时薄荷通过增加根生物量比来优先竞争矿质营养。

Effects of Planting Density on Growth Strategies and Photosynthetic Characteristics of Mentha haplocalyx Briq.

The main objectives of this study were to analyze the effects of planting density on growth strategies and photosynthetic characteristics of M. haplocalyx Briq. The results showed that： （1） the height, stem diameter, branch number, single leaf area and leaf thickness decreased with the increase in planting density. （2） The in- crease of planting density induced the decrease of chlorophyll content and net photosynthetic rate （Pn）, while the maximum quantum yield of photosystem II （Fv/Fm） was unchanged. （3） The biomass of root, stem and leaf as well as the total biomass of single plant decreased strikingly and the biomass of population kept constant with the increase in planting density, but biomass allocation of single plant and population was similar. Conse- quently, we thought that high planting density could depress photosynthetic capacity by affecting chlorophyll content in this study; the M. haplocalyx Briq could compete for mineral nutrients preferential by enhancing the root mass ratio with the increase of planting density.