【作者】 路海玲；

【导师】 孟亚利；

【作者基本信息】 南京农业大学 ， 作物栽培学与耕作学， 2011， 硕士

【摘要】 目前,我国土壤盐渍化面积日益扩大,严重影响了我国农业的发展,因此盐碱化土地的合理利用和改良对农业发展具有重要的意义。本研究采用盆栽方法模拟滨海混合盐土成分,以耐盐品种中棉所44和盐敏感品种苏棉12号为材料,于2008-2009年在江苏南京(118°50’E,32°02’N)南京农业大学牌楼试验站设置盐浓度处理(0:1.25 dS m-1、0.35%:5.80 dS m-1、0.60%:9.61 dS m-1、0.85%:13.23 dS m-1和1.00%：14.65 dS m-1)和水分处理(土壤相对含水量分别为75%和55%)试验,研究在正常灌水和轻度干旱条件下,不同程度盐胁迫对棉田土壤养分、土壤微生物生物量、土壤微生物群落多样性及土壤微生物数量、土壤酶活性的影响,探索盐胁迫抑制棉花生长的土壤生物学机制,为盐碱地棉花高产栽培调控提供理论依据。主要结果如下：1土壤盐分对棉田土壤微生物生物量和土壤养分的影响土壤盐胁迫显著抑制棉花生长,随着盐浓度的升高,棉株生物量、根重、铃数、铃重及籽棉产量均呈显著下降的趋势。在棉花整个生育期,棉田土壤微生物量碳、氮、土壤基础呼吸强度均随着盐浓度的升高而呈逐渐显著降低趋势,花铃期达到最大,而微生物量碳氮比则随盐浓度程度的增加有所增大。土壤中有机质、全氮、速效氮、有效磷、速效钾等养分含量的变化趋势与土壤微生物量碳、氮基本一致,但降幅较小。土壤微生物量碳与土壤有机碳的比值、土壤微生物量氮与土壤全氮的比值均随着盐浓度的升高而呈逐渐下降趋势。正常灌水条件下不同盐度处理的各项指标值均显著高于相应干旱处理的,干旱加重了盐分对土壤微生物量和土壤养分的抑制效应。相关分析表明：土壤微生物量与土壤速效氮、速效钾、有效磷之间呈显著正相关关系,与土壤pH值之间存在显著负相关关系。总体来说,土壤微生物量碳、氮受盐胁迫的影响大于土壤有机碳和全氮,土壤微生物对土壤有机碳和全氮转化效率显著降低。两个品种之间也存在一定的差异,在不同的盐分处理之下,中棉所44要比苏棉12号的各指标值要高一些。2土壤盐分对棉田土壤微生物群落多样性的影响采用Biolog微平板方法分析盐胁迫下棉田土壤微生物群落结构与代谢功能的变化,结果表明随着盐浓度的升高,土壤微生物群落平均吸光度值(AWCD)逐渐降低,棉田土壤微生物群落多样性Shannon指数和丰富度指数均随着盐浓度的升高而逐渐降低,各处理之间达到显著差异,说明盐胁迫引起土壤微生物群落发生明显变化,土壤微生物种类减少、代谢活性和功能多样性降低。正常灌水处理的AWCD值高于相应干旱处理,中棉所44的AWCD值高于苏棉12号,并且棉花花铃期的AWCD值要高于吐絮期。主成分分析表明：六大类碳源在各盐分处理之间利用率不一样,其中碳水化合物和氨基酸和羧酸三类碳源被利用的最多。对照处理要比各盐分处理利用的碳源种类多,正常灌水处理利用的碳源种类也要高于相应的干旱处理。3土壤盐分对棉田土壤微生物数量和土壤酶活性的影响盐胁迫加重了土壤中Na+、K+ Cl-、Mg2+、Ca2+的含量。棉田土壤微生物数量(细菌、真菌、放线菌、氨化细菌)均是随着盐浓度的升高而呈逐渐降低趋势,棉田土壤脲酶、碱性磷酸酶、过氧化氢酶均是随着盐浓度的升高而呈下降趋势。土壤水分的亏缺加重了盐胁迫的程度,中棉所44在不同盐分处理下各指标均要高于苏棉12号。相关分析表明：土壤微生物数量(细菌、真菌、放线菌、氨化细菌)、土壤酶(脲酶、碱性磷酸酶、过氧化氢酶)、土壤微生物量在棉花花铃期与棉田土壤Na+、K+、Cl-、Mg2+、Ca2+呈显著负相关关系。更多还原

【Abstract】 Soil salinization more and more stress in the china, and the soil salinization is a key environmental stress factor that limits crop growth and population development, it is very important to exploit and utilize this soil. Two cotton cultivars with different salt-tolerance (CCRI-44, Sumian 12) were used, and five salinity rates (0:1.25 dS m-1、0.35%:5.80 dS m-10.60%:9.61 dS m-1、0.85%:13.23 dS m-1 and 1.00%:14.65 dS m-1), standing for five levels respectively were applied. The study focused on:(1) Effects of salinity stress on cotton field microbial biomass and soil nutrient content at different growth stages in cotton field; (2) Effects of salinity stress on cotton field soil microbial community diversity at different growth stages in cotton field; (3) Effects of salinity stress on cotton field soil iron content and microbe quantity and soil enzyme activity at different growth stages in cotton field. The main results were as follows:1 Effects of salinity on soil microbial biomass and soil nutrient content at different growth stages in cotton fieldUnder the same soil water treatment, with increasing of soil salinity, the content of soil microbial biomass C, N was decreased. At the same time, the growth of cotton was inhabited by soil salinity stress. Root dry weight, biomass, and seed cotton yield all declined with the increase of soil salinity, and the soil organic matter, total nitrogen, available nitrogen, available phosphorus and rapidly available potassium was decreased, but soil metabolic quotient was go up with the increase of soil salinity. Under the same soil salinity, the content of soil nutrient were much higher in well-watering treatment than in water stress treatment. Compared to Sumian 12, CCRI-44 was less affected by soil salinity at different growth stages of cotton. Correlation analysis showed that the soil microbial biomass C,N had a significant positive correlation with soil nutrient content(available nitrogen, available phosphorus and rapidly available potassium), and had a significant negative correlation with soil pH. 2 Effects of salinity on soil microbial community diversity at different growth stages in cotton fieldUnder the same soil water treatment, the average well color development with incubation times was increased, but average well color development, shannon index and richness index were decreased with increasing of soil salinity. Under the same soil salinity, the average well color development, shannon index and richness index 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. Principal component analysis showed that six kinds of carbon source utilization rate was not the same affected by soil salinity at different growth stages of cotton, the carbohydrate was most.3 Effects of salinity on soil iron content, soil microbe quantity, soil enzyme activity at different growth stages in cotton fieldUnder the same soil water treatment, with increasing of soil salinity, the Na+, K+,C1-,Mg2+,Ca2+ content increased. But the the number of bacteria, fungi and actinomyces, ammonifying bacteria, the activity of urease, phosphatase, catalase decreased. At the same time, the growth of cotton was inhabited by soil salinity stress. Under the same soil salinity, the activity of soil enzyme, soil microbe quantity 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 activity of soil enzyme, soil microbe quantity had a significant negative correlation with soil Na+,Cl-, K+,Mg2+,Ca2+ content.更多还原