盐分对棉花光合特性及根际土壤CO_2浓度的影响

Effects of Salinity on Photosynthetic Characteristics of Cotton and CO_2 Concentration in Rhizosphere Soils

为了探寻不同盐分含量土壤棉花生长根际CO2浓度与光合指标之间的关系,通过桶栽试验,对4种盐分(CK:0%,F1:0.2%,F2:0.4%,F3:0.6%)处理下2种质地(砂土和壤土)土壤CO2浓度和棉花光合特征的变化规律进行了研究。结果表明:随着棉花生育期的推进,壤土和砂土的土壤CO2浓度均呈先升高后降低的"单峰"曲线变化趋势,峰值出现在花铃期,分别高达17 061.95,17 572.00μmol/mol。在盐分处理下不同质地土壤CO2浓度随土层深度的增加而增加,50cm处土壤CO2浓度均值为13 540.32μmol/mol,是表层10cm处的近2倍。随着盐分含量的增加,2种质地土壤CO2浓度差异显著,均呈下降趋势,且壤土CO2浓度明显高于砂土;盐分和土壤质地类型的相互作用对棉花净光合速率(Pn)达到极显著水平(P<0.01)。同一土壤质地类型条件下,各生育期棉花Pn随着盐分含量的增加而减小,均在F3处理下达到最小值,盐分含量较低时对棉花光合指标的影响不显著(P>0.05);同一盐分处理下,不同土壤质地棉花Pn差异显著,表现为壤土>砂土。不同盐分处理下2种质地土壤CO2浓度与棉花净光合速率之间密切相关,棉花Pn能够解释根际土壤CO2浓度变化的81.2%,说明盐分和土壤质地类型通过棉花净光合速率影响土壤CO2浓度的大小。研究结果可为作物生长环境提供理论参考。

In order to explore the relationship between photosynthetic index and the variation of CO2 concentration in the rhizosphere of cotton soils with different salinity contents,four different salinity treatments (CK:0%,F1:0.2%,F2:0.4%,F3:0.6%) were set,and the variation of soil CO2 concentration and photosynthetic characteristics of cotton under two soil texture (sandy soil and loam soil) were studied in barrel cultivated cotton.The results showed that with the development of cotton growth period,the CO2 concentration of the two soil textures both increased first and then decreased,and the peak values appeared at the flowering and boll stage,and the maximum CO2 concentration was 17 061.95 μmol/mol in loam and 17 572.00 μmol/mol in sandy soil.Under the salt treatments,the soil CO2 concentration of the two soil textures both increased with the increasing of soil depth.The average value of soil CO2 concentration at 50 cm soil depth was 13 540.32 μmol/mol,which was nearly two times that of the surface layer at 10 cm depth.With the increasing of salinity content,the difference of CO2 concentration between the two texture soils was significant,both of them showed a downward trend,and the CO2 concentration of loam soil was significantly higher than that of sandy soil.The interaction between salinity content and soil texture had extremely significant effects on net photosynthetic rate (Pn) of cotton (P<0.01).Under the same soil texture condition,Pn of cotton showed a downward trend with the increasing of salinity content at different growth stages,and reached the minimum value in F3 treatment,but the effect of low salinity content on cotton photosynthesis index was not significant (P>0.05).Under the same salinity treatment,there was significant difference in Pn of cotton between different soil textures,showing loam > sandy soil.There was a close correlation between CO2 concentration of two soil textures and cotton net photosynthetic rate under different salinity treatments,and cotton P n could explain 81.2% of the variation of CO2 concentration in rhizosphere soil,which indicated that salinity content and soil texture type affected soil CO2 concentration through cotton net photosynthetic rate.The results could provide a theoretical reference for the growth environment of crop.