盐胁迫对棉田土壤微生物数量与酶活性的影响

Effects of Salinity Stress on Cotton Field Soil Microbe Quantity and Soil Enzyme Activity

在盆栽条件下模拟滨海盐土组成,研究土壤盐胁迫对不同耐盐性棉花品种"中棉所44"和"苏棉12号"土壤微生物数量和土壤酶活性的影响。结果表明:从苗期到吐絮期,两个品种的土壤细菌、真菌和放线菌数量,以及土壤脲酶、蔗糖酶、碱性磷酸酶和纤维素酶活性均随土壤盐分的增加呈现逐渐下降的一致趋势,处理间差异均达显著水平。土壤水分亏缺加重盐胁迫影响,相同盐分水平下,正常灌水处理的土壤微生物数量和酶活性显著高于相应干旱处理。棉株的生长发育亦受到土壤盐分的显著抑制,根系活力、根重、生物量和籽棉产量均随土壤盐分水平升高而一致降低,根冠比则相反。耐盐性品种中棉所44各项测定指标的下降幅度均小于苏棉12号。相关性分析表明,各菌类数量和酶活性与籽棉产量之间存在显著的正相关关系,同时各菌类数量和酶活性之间密切相关,其中碱性磷酸酶和纤维素酶活性与各菌类数量之间的相关系数均达到极显著水平。说明土壤微生物与土壤酶活性对盐胁迫反应极为敏感,并与棉花产量密切相关,是盐胁迫下棉花显著减产的一个重要原因,可作为土壤盐胁迫过程中的重要指标。

The two-year experiment was conducted in pot with Sumian 12 （salinity-sensitivity） and CCRI-44 （salinity-tolerance） at Pailou experimental station in Nanjing agricultural university.Simulating the salinity component of seashore saline soil,setting five soil salinity rates （0%,0.35%,0.60%,0.85%,1.00%）and two soil water treatments including well-watering （（75±5）%）and water stress（ （55±5）%）,the objective of this study was to evaluate the effects of soil salinity on soil microbes and enzyme activities at different growth stages of cotton.The results showed that under the same soil water treatment,with increasing of soil salinity,the number of bacteria,fungi and actinomyces,and the activity of urease,invertase,phosphatase,celluloytic enzyme decreased.At the same time,the growth of cotton was inhabited by soil salinity stress.Root vigor,root dry weight,biomass,and seed cotton yield all declined with the increase of soil salinity,but R/S-ratio improved.Under the same soil salinity,the number of soil microbe and activity of soil enzyme were much higher in well-watering treatment than in water stress treatment.Soil water stress aggravated the effects of soil salinity stress.Compared to Sumian 12,CCRI-44 was less affected by soil salinity at different growth stages of cotton.Correlation analysis showed that the seed cotton yield had a significant positive correlation with soil microbe and soil enzyme,and the number of soil microbe was closely related with activity of soil enzyme,especially in phosphatase and celluloytic enzyme.Soil microbe and soil enzyme,which are sensitive to soil salinity stress and closely related with cotton yield,are the important reasons of cotton yield decreasing and important indices to extent of soil salinity stress.