孕穗期低温对冬小麦光合、干物质转运和产量的影响

Effects of Low-temperature at Booting Stage on Photosynthesis,Dry Matter Transport and Grain Yield of Winter Wheat

为探明低温对冬小麦光合作用、干物质转运和产量的影响,以西农979、小偃22和商麦5226为试验材料,在孕穗期进行不同强度的低温处理,测定光合特性、干物质积累、转运和分配及产量等性状变化。结果表明:(1)低温处理后,供试品种叶片净光合速率、蒸腾速率和气孔导度均显著下降,胞间CO_(2)浓度显著增加。(2)低温处理降低了开花期和成熟期单株干物质积累量、籽粒干物质积累量、茎秆+叶鞘+叶片干物质积累量、花前干物质转运量、干物质转运效率、干物质贡献率、花后干物质积累量和籽粒干物质分配比例。茎秆+叶鞘+叶片干物质分配比例、穂轴+颖壳干物质分配比例和花后干物质贡献率较对照有不同程度的增加。(3)低温处理显著降低了单株产量和穗粒数,连续3 d低温处理下西农979、小偃22、商麦5226单株产量分别下降38.2%、48.5%和75.9%,连续6 d低温处理下依次下降62.7%、76.6%和87.5%;低温胁迫也降低了单株穂数和千粒质量。孕穗期低温处理降低了小麦光合性能、营养器官干物质积累量和向籽粒的转运与分配,导致穗粒数和千粒质量大幅下降,是造成小麦减产的主要原因。综合来看,3个品种的孕穗期抗寒性表现为西农979>小偃22>商麦5226。

To quantify the effect of low temperature on photosynthesis,dry matter transport and grain yield of winter wheat,Xinong 979,Xiaoyan 22 and Shangmai 5226 were used as experimental materials.Different low temperature treatments were carried out at the booting stage and photosynthetic characteristics,dry matter accumulation,transport and distribution and grain yield were measured.The results showed that:(1)After low temperature treatment,the net photosynthetic rate,tran-spiration rate and stomatal conductance decreased significantly,while the intercellular CO_(2)concentration increased signifi-cantly.(2)Low temperature treatment reduced the dry matter accumulation of anthesis and maturity per plant,grain dry matter accumulation,stem+sheath+leaf dry matter accumulation,pre-anthesis dry matter translocation amount,dry matter translocation rate,dry matter contribution rate,after-anthesis dry matter accumulation and the distribution rate of grain dry matter.While the stem+sheath+leaf dry matter distribution rate,spike axis+glume dry matter distribution rate and post-an-thesis dry matter contribution rate increased to different degrees compared with the control.(3)Low temperature treatment significantly reduced the grain yield per plant and the number of grains per panicle.The yield per plant of Xinong 979,Xi-aoyan 22 and Shangmai 5226 decreased by 38.2%,48.5%and 75.9%under low temperature treatment for 3 consecutive days,and decreased by 62.7%,76.6%and 87.5%under low temperature treatment for 6 consecutive days.Meanwhile,low temperature stress reduced spike number per plant and the 1000-grain weight.Low temperature treatment at booting stage reduced the photosynthetic performance,dry matter accumulation in vegetative organs and the transport amount and distribution rate of dry matter to grain,resulting in a significant decrease in the number of grains per panicle and thousand-grain weight,which was the main reason for the reduction in wheat grain yield.On the whole,the cold resistance of the three varieties at booting stage was Xinong 979>Xiaoyan 22>Shangmai 5226.