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为探讨不同深耕时间对土壤理化性质及棉苗光合生产的影响,于冬前(T1)、开春(T2)、播前(T3)对滨海重度盐碱棉田进行深耕,测定棉花苗期叶面积指数(LAI)、光合特性、叶绿素含量(SPAD)以及干物质积累和分配情况,并对0~40 cm土层土壤含盐量、含水率和容重进行分层测定。结果表明,与T0(免耕直播)处理相比,T1处理各土层含盐量和含水率无明显变化,容重下降4.0%~9.1%,棉苗叶片SPAD、LAI以及根冠比增大8.0%~29.4%,光合参数增大4.1%~14.8%,棉苗总干质量增大9.8%;T2处理各土层含盐量降低47.2%~50.9%,10~40 cm土层含水率无显著变化,容重下降9.6%~18.2%,棉苗叶片SPAD、LAI以及根冠比增大23.6%~56.0%,光合参数增大14.2%~49.4%,棉苗总干质量增大45.6%;T3处理各土层含盐量增加14.5%~57.7%,含水率降低2.4%~8.7%,容重下降18.5%~25.4%,叶片SPAD和LAI分别降低13.0%和24.0%,光合参数降低21.4%~64.6%,棉苗总干质量降低21.9%。可见,开春深耕(T2处理)可有效改良滨海盐碱土壤,更有利于棉苗光合特性提高及其正常生长发育。
In order to investigate the effects of different deep plowing times on soil physical and chemical properties and photosynthesis of cotton seedlings, coastal salinity-salinized cotton fields were deeply plowed before winter (T1), open spring (T2) and before sowing (T3), and the leaf area index (LAI), photosynthetic characteristics, chlorophyll content (SPAD) and dry matter accumulation and distribution. Soil salinity, water content and bulk density were measured in 0 ~ 40 cm soil layer. The results showed that compared with T0 (no tillage and direct sowing), the salinity and water content of T1 soil did not change obviously, the bulk density decreased 4.0% ~ 9.1%, the SPAD, LAI and the ratio of root to shoot increased % ~ 29.4%, photosynthetic parameters increased by 4.1% ~ 14.8%, the total dry weight of cotton seedlings increased 9.8%; salt content of T2 treatment decreased 47.2% ~ 50.9% The content of SPAD, LAI and root-shoot ratio of cotton seedlings increased by 23.6% -56.0%, photosynthesis parameters increased by 14.2% -49.4%, and the total dry weight of cotton seedlings increased by 45.6%. T3 treatment Soil salt content increased by 14.5% -57.7%, water content decreased by 2.4% -8.7%, and bulk density decreased by 18.5% -25.4%. Leaf SPAD and LAI decreased by 13.0% and 24.0%, while photosynthetic parameters decreased by 21.4% -64.6% , Cotton seedling total dry mass decreased 21.9%. Can be seen that spring plowing (T2 treatment) can effectively improve coastal saline soil, more conducive to cotton seedling photosynthetic characteristics and their normal growth and development.