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期 刊 ：应用生态学报 2009年 20卷 08期 页码：1825-1831

关键词：环境因子；干旱河谷；海拔梯度；生物固氮；水分胁迫；

Keywords:environmental factor, dry valley, altitudinal gradient, biological nitrogen fixation, water stress,

摘 要 ：

通过野外调查，分析了岷江干旱河谷海拔梯度上相同年龄段的白刺花、岷谷木蓝和小雀花幼苗根系结瘤、生物量积累、生物量百分比的变化及其相互关系；人为控制土壤水分（田间持水量(WHC)的80%、60%、40%和20% 4个水平）研究了干旱对2月龄的白刺花与小雀花幼苗结瘤能力的影响.结果表明：1)干旱河谷低海拔地段(1600～1950 m)幼苗的结瘤能力都很低，白刺花、岷谷木蓝和小雀花的平均结瘤数分别为每株(0.1±0.1)、(0.9±0.5)和(5.7±1.9)个，未结瘤的个体分别占651%、123%和176%；总体上随着海拔的升高，3种幼苗的根瘤数均呈增加趋势，且与细根百分比及根长正相关.2)土壤水分低于60% WHC时，白刺花与小雀花的根瘤数及生物量均明显减小；在20% WHC条件下，白刺花根瘤数为0，小雀花根瘤数为每株(9.8±3.6)个.综合分析发现，干旱河谷地区豆科灌木的结瘤固氮能力很低，土壤水分在40% WHC以上时其生物固氮才能有效发挥，与白刺花相比，小雀花结瘤能力较高，干旱忍受性较强.

Abstract:

A field investigation was made to understand the seedlings root nodula
tion, biomass accumulation, root length, and fine root percentage of Sophora d
avidii, Indigofera lenticellata and Campylotropis polyantha along an alt
itudinal gradient on two contrasting sloped hills (north Zongqu and south Jingzh
oushan) 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 thr
ee test shrub species, fewer nodules were observed at lower altitude (1600〖KG-*
2〗-〖KG-*7〗1950 m) areas, the nodule number per plant of S. davidii, I. lent
icellata, and C. polyantha being 01±01, 09±05, and 57±19, a
nd the non-nodulation plant accounting for 651%, 123% and 176%, respectiv
ely. The nodule number of the three species increased with increasing altitude,
and correlated positively with root length and fine root percentage. However, th
ere 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. davidi
i 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, respec
tively, indicating that in this dry valley, the root nodulation capability of en
demic leguminous shrubs was very low. Comparing with S. davidii, C. polyan
tha had higher root nodulation capability and drought-resistance. Prior
 to introducing these shrub species in forestation practices, to keep the soil m
oisture content higher than 40% WHC was recommended for relatively efficient bio
logical nitrogen fixation.

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