干旱胁迫对小叶杨幼苗生长的影响

目的]了解小叶杨的抗旱机理,为山西省北部半干旱风沙区小叶杨防护林建设提供科学依据。方法]通过在山西省苗圃基地盆栽模拟干旱试验,以小叶杨生长过程中的苗木株高和地径,根、茎、叶生物量,叶片相对含水量和水势,净光合速率、蒸腾速率等为生长和生理指标,研究干旱胁迫对小叶杨幼苗生长的影响。结果]干旱胁迫抑制了小叶杨幼苗的生长,包括地上部分和根系的生长;叶片相对含水量和水势随土壤相对含水量降低而下降;各干旱梯度下CK,T1,T2,T3,T4,T5的净光合速率、蒸腾速率也随干旱梯度加深而降低,但从CK(田间持水量,土壤含水量20.3%)到T3(田间持水量的40%,土壤含水量8.12%)净光合速率和蒸腾速率随干旱梯度加深降幅逐渐较小,并且干旱时也能保持较大的光合速率和蒸腾速率,表明小叶杨具有明显抗旱特性;当土壤水分进一步减少,T4(田间持水量的30%,土壤含水量为6.09%)时小叶杨开始出现干枯现象,T5(田间持水量量的20%,土壤含水量为4.06%)时小叶杨全部死亡。结论]山西省西南部及其周边地区进行小叶杨造林时,土壤水分应尽量要保持在6.09%(T4)以上。

Drought Stress Effects on Growth of Populus Simonii Seedlings

Objective] This paper aimed to explore the drought resistance mechanism of Populus simonii, and to provide a scientific basis for the construction of the shelterbelt in the northern of Shanxi Province.Methods] The effect of drought stress on Populus simonii seedling growth was studied based on the pot experiment conducted in the Taidu nursery base of Jixian Forestry Bureau in the southwest of Shanxi Province. The experiment simulated drought conditions and used the Populus simonii from a loess gully region as the provenance material. And height and ground diameter of the seedling, the biomass in leaves, stems and roots, the relative water content and water potential, net photosynthetic rate, transpiration rate and other growth and physiological indexes were measured in order to study the effects.Results] The results showed that drought stress inhibited the growth of the Populus simonii seedlings, including the aboveground parts and the root system; Leaf relative water content and water potential decreased with the reduction of the relative water content of soil. In different drought gradient treatments(CK,T₁,T₂,T₃,T₄,T₅), net photosynthetic rate and transpiration rate slowed down with the severeness of drought stress. However, in the treatments of CK(field capacity) to T₃ (40% of field capacity, soil water content is 8.12%), the declined rates were gradually smaller; in addition, the Populus simonii seedlings could maintain a relative large photosynthetic rate and transpiration rate, which indicated that Populus simonii had obvious drought resistance. When soil moisture further reduced, Populus simonii appeared to be drying in the period of T₄ (30% of field capacity, soil water content is 6.09%), and in T₅ (20% of feild capacity, soil water content is 4.06%) all died.Conclusion] In the southwest of Shanxi Province and the surrounding areas, soil water should be stayed above 6.09%(T₄) as far as possible while planting Populus simonii.