不同穗型小麦品种旗叶光合作用日变化的研究

在大田条件下，对多穗型小麦品种豫麦49和大穗型小麦品种周麦13的旗叶净光合速率（Pn)及基影响因素，包括叶温（T1）、光合有效辐射（PAR）、蒸腾速率（Tr)、气孔导度（C）、细胞间隙CO2浓度（Ci)等日变化的测定结果表明，开花期2品种都存在光合“午休”现象，豫麦49Pn日变化呈双峰曲线，峰值出现在10：00和14：00，周麦13Pn日变化为单峰曲线，峰值在10：00。相关分析表明，开花期的温度和光照对豫麦49旗叶光合已造成一定程度的影响，此期的光温条件较有利于周麦13旗叶的光合作用。灌浆中期2品种均表现出一降不起型的严重“午休”现象，在强光、高温下，豫麦49旗叶Pn比周麦13降低明显。

Study on diurnal changes of flag leaf photosynthetic rate for two spike-type cultivars of wheat

Under field conditions,two winter wheat cultivars,Yumai 49 and Zhoumai 13,were used to determined the diurnal changes of flag leaf net photosynthetic rate (Pn) and its major affecting factors,i.e.leaf temperature (Tl),photosynthetically active radiation (PAR),transpiration rate (Tr),stomatal conductance (C) and intercellar CO 2 concentration (Ci).The results indicated that the Pn of both the two cultivars showed midday depression phenomenon at anthesis.The Pn of Yumai 49 varied as a two-peaked curve,whose peak values reached at 10:00 and 14:00,but Zhoumai 13 varied as a single-peaked curve with peak value reached at 10:00.The relationship between the Pn and its affecting factors were analysed by the correlation analysis,the temperature and solar radiation at anthesis had affected the Pn of Yumai 49 in some degree,but which avail to that of Zhoumai 13.Both the two cultivars showed serious midday depression phenomenon at middle-filling,and the Pn of Yumai 49 decreased more serious than that of Zhoumai 13 at this stage.