大豆光合速率对光照度和土壤水分的响应

Effects of Soil Moisture and Light Intensity on Photosynthetic Rates of Glycine max

为了探讨光照度（PAR）和土壤水分（SRWC）对大豆叶片净光合速率（Pn）的综合影响,构建Pn与相关环境因子的数学模型,设定6个SRWC梯度（相对含水量30%~80%）,盆栽大豆,测量光响应参数、Pn等。结果表明,SRWC为40%~80%,大豆叶片Pn与SRWC呈显著的正相关关系,但PAR对Pn的影响程度是随着SRWC的变化而改变的;不同SRWC处理之间,Pn对PAR响应变化的趋势相同,均随着PAR的增大先快速增大然后增大速度变缓并伴随光饱和现象的发生;SRWC较低时,SRWC对Pn的影响占主导地位,在SRWC较高时,PAR对Pn的影响占主导地位;SRWC和PAR对Pn的综合影响可以用数学模型来表达,影响大豆Pn的主导因子由SRWC过渡到PAR,土壤水分的临界值为63.19%。

In order to explore the combined effects of light intensity （PAR） and soil moisture （SRWC） on net photosynthetic rate （Pn） of Glycine max leaves,and to construct the mathematical model of Pn and environmental faetors,a gradient of SRWC content at an interval of 10% within the range of 30%-80% was installed for Glycine max in a pot culture experiment,with the light response parameters,Pn and several other parameters measured. The experimental results showed that there was a significant positive correlation between Pn and PAR when the SRWC holding capacity was in the range of 40%-80%.Both PAR and SRWC had impacts on Pn,and the affecting magnitude varied with SRWC content.Among the SRWC treatments,the response of Pn to PAR showed the same change trend.In general,Pn increased rapidly firstly and then increase speed became slow along with the light saturation phenomenon.At low SRWC, SRWC influence on Pn dominates,at higher SRWC,PAR affect Pn of the dominant.The comprehensive impacts from PAR and SRWC to Pn could be expressed by a exponential, mode,and the dominant factor affecting Pn translate from SRWC to PAR. Using the constructed mode, we found that the threshold of appro- priate soil moisture content for Glyeine max was 63.19%.