施氮量对套作大豆花后光合特性、干物质积累及产量的影响

在“玉米-大豆”套作模式下,以贡选1号为材料,研究了施氮量对套作大豆花后光合特性、干物质积累量及产量的影响。结果表明,花后Chl a含量、Chl a/b值、净光合速率、叶、叶柄、茎和荚的干重以及地上部干物质积累总量均以低氮处理(纯氮32.4 kg/hm²)最优,其次为中氮处理(纯氮64.8 kg/hm²)。套作大豆的产量和有效荚数均以低氮处理最高,分别较对照(不施氮)高18.22%和17.37%,差异极显著;其次为中氮处理,与对照差异显著;高氮处理(纯氮97.2 kg/hm²)则显著低于对照,这是由于经高氮处理的大豆植株花后叶面积指数(LAI)过高,影响通风透光,落花落荚严重所致。可见,合理施用氮肥(纯氮32.4, 64.8 kg/hm²)能提高套作大豆花后叶片的净光合速率,地上部干物质积累量,进而提高大豆产量。

Effects of different nitrogen levels on photosynthetic characteristics, dry matter accumulation and yield of relay strip intercropping Glycine max after blooming

In the relay strip intercropping system of "Zey mays-Glycine max",the G.max cultivar,Gongxuan 1,was used to study the effects of different nitrogen levels on photosynthetic characteristics,dry matter accumulation and yield of G.max after blooming.The results showed that the optimal treatment on the Chl a content,Chl a/b ratio,net photosynthetic rate(Pn),the dry weight of leaf blade,leaf stalk,stem and pod and the total above-ground biomass after blooming was the lower nitrogen level(32.4 kg/ha),followed by the middle nitrogen level(64.8 kg/ha).The optimal treatment on the yield and number of pods was also the lower nitrogen level,which were 18.22% and 17.37% higher than those in the controls respectively,the difference was very significant;followed by the middle nitrogen level;those of the higher nitrogen treatment(97.2 kg/ha) were significantly lower than those in the controls,which was due to the higher leaf area index(LAI) for high nitrogen treatment to result in hindering ventilation and transmission light.So,the appropriate nitrogen(32.4,64.8 kg/ha) could improve the net photosynthetic rate(Pn) and the total above-ground biomass,accordingly improve yield.