晋西北柠条长期种植对根系分布及土壤水碳的影响

[目的]探究晋西北不同种植年限人工柠条深层土壤水碳和根系的相互作用,为黄土丘陵区人工植被恢复提供一定的理论基础。[方法]以不同种植年限(20,40,60 a)柠条林为研究对象,对0—300 cm土层水分、有机碳和根系特征参数进行测定,分析了三者的相互关系。[结果](1)相较于荒草地,柠条长期种植(大于40 a),降低了剖面土壤水分含量,但增加了剖面土壤有机碳含量。土壤水分亏缺现象主要集中在0—60,200—300 cm土层中,而有机碳含量主要分布在0—60 cm土层中。柠条种植显著增加了0—60 cm剖面根系特征参数,其根系生物量占0—300 cm土层的50%。(2)在0—60 cm土层,有机碳与土壤水分显著负相关(p<0.01),与根体积密度显著正相关(p<0.05);在60—200 cm土层,土壤水分与有机碳、根表面积密度和根体积密度显著负相关(p<0.05);在200—300 cm土层,土壤水分与根系参数均显著正相关(p<0.05)。多元回归和通径分析结果表明根体积密度和土壤水分是影响有机碳的主要因素,较高的根体积密度和较低的土壤水分有助于增加土壤有机碳。[结论]晋西北黄土丘陵区长期种植柠条后,对表层根系特征参数的增加促进了土壤有机碳积累,但加剧了表层土壤水分消耗,并促使根系向深层生长以适应水分条件。在区域进行植被建设时有必要综合考虑植被种植年限和土层深度对土壤水分、有机碳和根系特征的综合影响。

Effects of Gradual Water Deficit Stress on Phenological and Morphological Traits in Chickpea （Cicer arietinum L.）

The aims of this study were to investigate the effect of gradual water deficit stress on some phonological and morphological traits and grain yield of desi and kabuli chickpea cultivars. This study was carried out in 2007 and 2008, to evaluate responses of three chickpea cultivars （Hashem and Arman from kabuli and Pirooz from desi type） under well watering （I1： 70mm evaporation from class A pan）, gradual water deficit （12 and 13： 70→90→ 110→130 and 70→100→130mm evaporation from class A pan, respectively） and severe water stress （14： 130mm evaporation from class A pan）. Result showed that days to flowering and plant height were decreased, as water limitation increased. This reduction was significant under gradual water stress （I2 and I3） and Severe water deficit （I4）, compared with control （I1）. There were no significant differences in grain filling period and grain yield among I~, I2 and I3 irrigation treatments. No significant differences in days to physiologic maturity and number of sub branches were recorded among irrigation treatments. Interactions of year×cultivar for days to physiologic maturity, grain filling period and grain yield （P≤0.01） and for days to flowering and plant height （P≤0.05） were significant. The superiority of Arman in producing comparatively greater grain yield could be attributed to higher grain filling period of this cultivar in both years.