在退化土壤上施用膨润土-腐植酸能改善土壤物理性质和水文特性，因其有改善土壤结构、提高水分和养分保蓄能力，但是缺少对土壤理化性质和生物学特性及籽粒品质的影响。本文主要研究了在中国半干旱地区沙地上施用30吨/公顷的膨润土-腐植酸后1、3、5和7年的影响。施用膨润土-腐植酸显著提高了土壤充水空隙度和土壤有机碳，尤其是在施用后第3年和5年。沙地上施用膨润土-腐植酸也提高了土壤微生物生物量碳、氮、磷和脲酶、蔗糖酶、过氧化氢酶和碱性磷酸酶的活性。玉米生育时期可分别解释土壤微生物生物量和酶活性总变异度的58%和84%。相比而言，施用膨润土-腐植酸解释了8%的总变异度。膨润土-腐植酸显著改善了半干旱地区土壤性质和玉米对氮磷的吸收。膨润土-腐植酸的利用可成为中国东北及世界上与之有相似土壤和气候的地区修复退化沙地土壤和促进可持续农业发展的一种有效的管理策略。

Alkali stress can cause severe crop damage and reduce production. However, physiological processes involved in alkali stress in oat seedlings are not well understood. In this study, physiological responses and yield of oat to alkali stress were studied using the alkali-tolerant oat genotype Vao-9 and the alkali-sensitive oat genotype Baiyan 5. The results were: (i) low concentrations of alkali stress (25 and 50 mmol L-1) significantly reduced the yield and grain weight while increased the oat grain number per spike. A negative correlation between yield and malondialdehyde (MDA) content at the jointing and grain filling stages and positive correlations between yield on one hand and superoxide dismutase (SOD), and peroxidase (POD) activities on the other at the jointing stage were observed. There was a positive correlation between MDA and soluble sugar at the grain filling stage; (ii) soluble sugar content was increased at the jointing and grain filling stages and decreased at the heading stage by alkali stress; (iii) alkali stress increased the SOD activity during the heading and grain filling stages, and increased the POD activity at the heading stage. As compared to the control, the increase of MDA contents in alkali-treated oat was observed, during the jointing, heading and grain filling stages; (iv) under alkali stress, the oat genotype Vao-9 showed higher antioxidant enzyme activity and lower soluble sugar contents during the heading stage, and lower MDA contents than those in the oat genotype Baiyan 5 under alkali stress. The result suggested that the high ROS scavenging capacity and soluble sugar levels might play roles in oat response to alkali stress.