盐胁迫对棉田土壤微生物量和土壤养分的影响

Effects of Salt Stress on Soil Microbial Biomass and Soil Nutrients in Cotton Field

以耐盐品种中棉所44为材料,模拟滨海混合盐土成分,研究了正常灌水(土壤相对含水量保持在75±5%)和轻度干旱(55±5%)下,不同程度盐胁迫(0,0.35%,0.60%,0.85%,1.00%)对棉田土壤微生物量和土壤养分的影响。结果表明,棉花产量及产量构成(铃数和铃重)、生物量、根重均随着盐浓度的升高而显著递减。棉田土壤微生物量C和N在棉花各个生育期内均随着盐浓度的升高而显著降低,花铃期达到最大,土壤有机质、全氮、速效N、有效P、速效K等养分含量的变化趋势与土壤微生物量C和N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、土壤微生物量氮与全氮的比值均随着盐浓度的升高而呈现逐渐下降的趋势,表明了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,也表明了土壤微生物对土壤有机碳和全氮转化效率的显著减低。正常灌水条件下各盐分处理的棉花生物量、铃数、铃重、根重、土壤微生物量和土壤养分含量均显著高于相应干旱处理,干旱加重了盐分对土壤微生物量和土壤养分的抑制效应。土壤微生物量C和N与土壤pH值之间存在显著负相关,与土壤有机质、全氮、速效N、有效P、速效K之间均存在显著正相关。

The experiment was completed in pot with CCRI-44（salinity-tolerance） at Pailou experimental station in Nanjing Agricultural University.By simulating the salinity component of seashore saline soil,setting five soil salinity rates（0%,0.35%,0.60%,0.85%,1.00%）,two soil water treatments including well-watering（soil relative water content is 75±5%） and water stress（soil relative water content is 55±5%）,this study aims to assess the effects of soil salinity stress on soil microbial biomass C and N,and soil nutrient in cotton field.The results showed that seed cotton yield,boll number,boll weight,biomass and root weight significantly declined with increasing soil salinity.At the same time,the soil microbial biomass C and N significantly declined with increasing soil salinity at different growth stages of cotton.For each salinity rate treatment,the microbial biomass C and N at the flowering and boll-forming stage were the highest in all four stages.Compared with CK（soil salinity rate is 0%）,the microbial biomass C in different salinity rates decreased by 14.69%~64.32%,and the microbial biomass N decreased by 7.59%~56.81% at flowering and boll-forming stage under the well-irrigated.Soil organic matter,total N,available P,rapidly available N,and rapidly available K were all reduced with increasing soil salinity at different growth stages of cotton.At the same time,soil water stress aggravated the effects of salinity stress on seed cotton yield,boll,boll weight,biomass and root weight,soil microbial biomass and soil nutrients.Correlation analysis demonstrated that soil microbial biomass C and N were significantly positively correlated with soil organic matter,total N,available P,rapidly available N,rapidly available K,seed cotton yield,biomass,and root weight,but significantly negatively correlated with soil pH.