【摘要】 以云南松苗木为研究材料,采用称重法控制土壤含水量对苗木进行干旱胁迫,探讨不同干旱胁迫强度对云南松苗木生长形态指标、生物量及碳酸酐酶活性的影响。结果表明:(1)相对于针叶长来说,地径对干旱胁迫更为敏感,程度较小的干旱胁迫即可引起地径生长的显著降低;随着干旱胁迫程度的加大,主根长呈先增加后减小的变化趋势,中度干旱胁迫(T4)是主根长生长的转折点。(2)高强度干旱胁迫对苗木生物量的抑制效应在器官间表现不均衡,苗木根受到的抑制作用更强;中度干旱胁迫(T4)处理时苗木根生物量比最大,同时叶生物量比最小,一定程度的干旱胁迫有利于苗木对根和叶生物量比的调整。(3)随着干旱胁迫强度的增大,苗木根、茎、叶的碳酸酐酶活性皆呈逐渐下降的趋势,方差分析和多重比较表明,可根据根中的碳酸酐酶活性来初步筛选耐旱性更强的优良单株。总之,该年龄段苗木的地径越大、主根长越长、根生物量比越大、根部的碳酸酐酶活性越高,苗木的耐旱能力越强,越有利于苗木在石漠化生境中的成活和生长。更多还原

【Abstract】 This study examined the effects of drought stresses on the morphological indexes and carbonic anhydrase activity of Pinus yunnanensis seedlings. The results were as following: 1) The ground diameter was the most sensitive to drought stress compared with the needle length of the seedlings. The low level of drought stress can result in a significant decrease in ground diameter increment. The taproot length increased to maximum at medium treatment and then decrease along the levels of drought stresses. 2) The changes in roots, stems, leaves and total biomasses in P. yunnanensis seedlings generally decreased along the levels of drought stresses. The inhibiting effect of drought stress on root growth was greater than that on stems and leaves. The effect of drought stress on biomass proportion was ranked as leaves > stems ≈ roots. The roots were more sensitive to the increasing drought stress intensity with the highest adjustment of root ratio in the seedlings observed at the treatment of moderate drought stress. Whereas, higher levels of drought stresses were not conducive to the improvement of their resilience in terms of the biomass allocation. 3) The activities of carbonic anhydride in roots, stems and leaves of P.yunnanensis seedlings decreased with the increase of intensity drought stress. The results from variance analysis and multiple comparisons showed that the activity of carbonic anhydrase in roots was an important prediction for the drought tolerance.We concluded that longer taproot length, and higher ground diameter, root biomass, and carbonic anhydrase activity of roots may be important implication for the evaluation of drought-resistant ability, as well as the capacity of survival and growth of P. yunnanensis seedlings in rocky desertification habitat.更多还原