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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。
With salt-tolerant Zhongmiansuo 44 as the material, the composition of coastal mixed saline soil was simulated to study the effect of salt stress on soil salinity under normal irrigation (soil relative water content kept at 75 ± 5%) and light drought (55 ± 5%), 0,0.35%, 0.60%, 0.85%, 1.00%) on soil microbial biomass and soil nutrient in cotton field. The results showed that cotton yield and yield components (boll number and boll weight), biomass and root weight all decreased significantly with the increase of salt concentration. Soil microbial biomass C and N decreased significantly with the increase of salt concentration in cotton at all growth stages and reached the maximum at the flower-boll stage. The changes of soil organic matter, total nitrogen, available N, available P, available K The trend is basically the same as that of soil microbial biomass C and N, but the decline is small. The ratios of soil microbial biomass carbon to soil organic carbon and the ratios of soil microbial biomass nitrogen to total nitrogen all decreased gradually with the increase of salt concentration, indicating that soil microbial biomass carbon and nitrogen was more affected by salt stress than soil organic Carbon and total nitrogen, also showed that soil microorganisms significantly reduced the conversion efficiency of soil organic carbon and total nitrogen. Under normal irrigation conditions, the soil biomass, boll number, boll weight, root weight, soil microbial biomass and soil nutrient content under different salt treatments were significantly higher than those under drought stress. Drought aggravated the inhibitory effect of salt on soil microbial biomass and soil nutrient . There was a significant negative correlation between soil microbial biomass C and N and soil pH, and there was a significant positive correlation with soil organic matter, total nitrogen, available N, available P and available K.