生殖生长期遮光处理对大豆叶片光合生理和衰老的影响

Effects of Shade on Photosynthetic Physiology and Senescence of Soybean Leaves during Reproductive Growth Period

大豆是我国重要的粮食作物和油料作物,在我国粮食安全中占有重要地位。生殖生长期是大豆产量形成的关键时期,该时期遮光限制带状间作大豆的产量。以不同耐荫大豆品种为试材,设置不同的遮光处理(0,50%和75%遮光),研究生殖生长期遮光对大豆叶片光合生理和衰老的影响。结果表明:生殖生长期遮光显著降低了大豆的单株叶面积、叶片光合速率、初始荧光强度(F0)、PSⅡ实际光化学效率(ΦPSⅡ)和叶绿素荧光光化学淬灭系数(qP),且均随着遮光程度的增加而降低;遮光会增加大豆叶片的叶绿素a、b和a+b含量,且随着遮光程度的增加而增加。表明遮光条件下,大豆叶片通过增加叶绿素含量提高对光能的捕获能力,但光合速率和光合面积的下降导致其整体的光能截获能力和转化能力变弱。遮光显著增加叶片的丙二醛(malondialde⁃hyde,MDA)含量和抗氧化酶活性;显著的降低了光合势,表明遮光促进了大豆叶片的衰老。耐荫品种具有更强的光合能力和较低的叶片衰老速度,这有利于其在遮光条件下获得更高的产量。

Soybean is one of the most important food crops as well as oil crops,and occupies an important place in the food security.The reproductive growth period is the key period of soybean yield formation,which restricts the yield of intercropping soybean.Different shade-tolerant soybean cultivars were used,and different shading treatments(0,50%and 75%)were set up to study the effects of shading on photosynthetic physiology and leaf senescence during reproductive growth period.The results showed that shading significantly reduced leaf area,leaf photosynthesis rate,initial fluorescence intensity(F0),PSII actual photochemical efficiency(ΦPSⅡ)and photochemical quenching of chlorophyll fluorescence(qP)of soybean.The amount of chlorophyll a,b and a+b in soybean leaves increased with the increase of the shade.It suggested that the photoenergy capture ability of soybean leaves increased by increasing chlorophyll content,but the decrease of photosynthetic rate and photosynthetic area led to the decrease of photoenergy capture and transformation ability.Malondia dehyde(MDA)content and antioxidant enzyme activity were significantly increased by shading.The leaf area duration was significantly reduced,indicating that the shade promoted the leaf senescence.Shade-tolerant cultivars have higher photosynthetic capacity and lower leaf senescence rate,which is conducive to higher yield under the condition of shading.