不同土壤水分对幼龄梨树生理特性及生物量的影响

以山西省吉县地区幼龄梨树为研究对象,在盆栽试验的基础上,研究了不同土壤水分条件对幼龄梨树生长相关生理指标的影响。结果表明,幼龄梨树的蒸腾速率日变化趋势在SWC≤10%时,呈现双峰曲线,第一峰值出现在上午10时,第二个高峰出现在14时左右。SWC>10%时,蒸腾速率日变化为单峰曲线,在中午12时达到一天中的最大值;不同土壤水分条件下,幼龄梨树净光合速率日变化呈“S”形,在上午8时左右达到最大峰值,在12时左右出现“光午休”低谷,土壤水分缺失明显降低净光合速率。发挥较大水分利用效率的土壤含水量范围为10%～14%。单株幼龄梨树的生物量分布总体为干>根>叶>枝,土壤水分较为充足时幼龄梨树积累的干物质的分配有偏向于叶和枝的趋势;而在干旱的情况下幼龄梨树干物质分配有偏向于根和干的趋势。

Effects of Different Soil Water Conditions on Physiological Characteristics and Biomass of Young Pear Tree

Taking young pear trees in Jixian Country, Shanxi Province for an example, the paper analyzes the effects of different soil water conditions on physiological characteristics of young pear tree based on a potted exper-iment. The result indicates that the daily change in t ranspirat ion rate presents a single-peak or double-peak curve and the relat ionship between water consumption of pear tree and soil water content can be described significantly by a quadratic curve. Under different soil water conditions, daily chang e in net photosynthetic rate of young pear tree presents/S0 shape, which rises to a peak at 8: 00 am and appears a midday depression of photosynthesis at 12: 00am. Soil water deficient markedly reduces photosynthetic rate. Soil water content suitable for high w ater use ef f-iciency is 10% ~ 14%. The dried weig ht of leaves and total biomass of young pear tree has a downtrend w ith decreased soil water content. U nder the normal soil water condition, the proportions of biomass overground and underground are nearly the same, but the greater photosynthetic production of young pear tree tends to occur in the underground.