Li Fang-Lan, Zhu Lin-Hai, Bao Wei-Kai
Chengdu Institute of Biology, Chinese Academy Sciences, Chengdu, China.
Ying Yong Sheng Tai Xue Bao. 2009 Aug;20(8):1825-31.
A field investigation was made to understand the seedlings root nodulation, biomass accumulation, root length, and fine root percentage of Sophora davidii, Indigofera lenticellata and Campylotropis polyantha along an altitudinal gradient on two contrasting sloped hills (north Zongqu and south Jingzhoushan) in the dry valley of Minjiang River. In the meantime, a greenhouse experiment was conducted to study the adaptation responses of 2 month-old S. davidii and C. polyantha seedlings root nodulation to different soil moisture regimes (80%, 60%, 40%, and 20% WHC). For the three test shrub species, fewer nodules were observed at lower altitude (1600-1950 m) areas, the nodule number per plant of S. davidii, I. lenticellata, and C. polyantha being 0.1 +/- 0.1, 0.9 +/- 0.5, and 5.7 +/- 1.9, and the non-nodulation plant accounting for 65.1%, 12.3% and 17.6%, respectively. The nodule number of the three species increased with increasing altitude, and correlated positively with root length and fine root percentage. However, there were no significant differences in the plant growth and biomass at different altitudes. When the soil moisture content was lower than 60% WHC, the nodule number and the fresh and dry mass of both S. davidii and C. polyantha decreased markedly, and at 20% WHC, no nodule and only 9.8 +/- 3.6 nodules were observed for S. davidii and C. polyantha, respectively, indicating that in this dry valley, the root nodulation capability of endemic leguminous shrubs was very low. Comparing with S. davidii, C. polyantha had higher root nodulation capability and drought-resistance. Prior to introducing these shrub species in forestation practices, to keep the soil moisture content higher than 40% WHC was recommended for relatively efficient biological nitrogen fixation.
在岷江干旱河谷两个截然不同的山坡（宗渠北部和荆州山南部），沿海拔梯度对绢毛槐、网叶马棘和多花杭子梢的幼苗根瘤形成、生物量积累、根长和细根比例进行了实地调查。同时，开展了温室试验，研究2月龄绢毛槐和多花杭子梢幼苗根瘤形成对不同土壤水分状况（80%、60%、40%和20%的田间持水量）的适应反应。对于这三种受试灌木物种，在低海拔（1600 - 1950米）地区观察到的根瘤较少，绢毛槐、网叶马棘和多花杭子梢单株根瘤数分别为0.1±0.1、0.9±0.5和5.7±1.9，未结瘤植株分别占65.1%、12.3%和17.6%。这三种物种的根瘤数随海拔升高而增加，且与根长和细根比例呈正相关。然而，不同海拔高度的植株生长和生物量没有显著差异。当土壤含水量低于60%的田间持水量时，绢毛槐和多花杭子梢的根瘤数以及鲜重和干重均显著下降，在20%的田间持水量时，绢毛槐未结瘤，多花杭子梢仅观察到9.8±3.6个根瘤，这表明在这个干旱河谷，乡土豆科灌木的根瘤形成能力非常低。与绢毛槐相比，多花杭子梢具有更高的根瘤形成能力和抗旱性。在造林实践中引入这些灌木物种之前，建议将土壤含水量保持在高于40%的田间持水量，以实现相对高效的生物固氮。
