两种梭梭根部输导组织坚韧度及其抗旱性

Drought Resistance and Rigidity of Root Conductive Tissue of Two Species of Haloxylon Bunge

以梭梭和白梭梭一年生盆栽幼苗为试材,测定60%(对照)、40%和20%的土壤相对含水量(SRWC)处理20d后两种梭梭同化枝的电导率和含水量,地上和地下部水势,根部木质素、纤维素、半纤维素含量,根肉质化程度和根长度。结果表明:两种梭梭同化枝含水量随着SRWC的下降均保持较高的水平;SRWC为40%和20%时,两种同化枝电导率的变化不显著,且均保持较低的值;两种梭梭地下部与地上部水势差值随土壤含水量的降低而增大;SRWC为40%的土壤条件促进两种梭梭的根系生长,20%的SRWC条件下仍保持与对照一样的水平;不同SRWC条件下,梭梭和白梭梭根部的木质素、纤维素、半纤维素含量的变化幅度均较小,且保持很高的水平,总含量分别为46·9%～53·3%和50·6%～57·6%。由此推断,在干旱胁迫下两种梭梭的根系依赖于较强的根部输导组织坚韧度,往土壤深层扎根找水,适应干旱环境。

In this article, one-year-old potted seedlings ofHaloxylon ammodendron and H. persicum were used as experimental materials, and subjected tO 60%, 40% and 20% soil relative water contents （SRWC） for 20 d. Electric conductivity, water content of assimilating shoots, water potentials of roots and shoots, lignin, cellulose and hemicellulose contents of roots, root carnification extent and root length of seedlings of the two Haloxylon species were measured. The results indicated that the water content in assimilating shoots of the two species kept at a high level, while the SRWC was gradually decreased. The two species of Haloxylon did not show significant change and kept at lower levels of electric conductivity under 40% and 20% SRWC treatments. The difference in water potential between roots and assimilating shoots of the two Haloxylon species were increased with decreasing of SRWC. The root growth was accelerated by 40% SRWC condition, and it was maintained in the same level as control plants under 20% SRWC condition. There were small differences in lignin, cellulose and hemicellulose contents between H. ammodendron and H. persicum, and kept at high levels of those components. Total contents of lignin, cellulose and hemicellulose were 46.9%-53.3% and 50.6%-57.6% in H, ammodendron and H. persicum, respectively. It is deduced therefrom that the two Haloxylon species adapt to drought environment by growing of roots to deeper layers of soil depending on the strong rigidity of root conductive tissue to absorb more water under drought conditions.