中文摘要：

经长期观察发现,某些小麦品种的部分主茎或分蘖（异常茎）具旗叶较倒二叶先衰老的特征,与常见的叶片衰老次序相反。为揭示这类品种的生物学特性,探讨其理论意义和应用价值,2005—2011连续6年,以正常小麦为对照,对其异常茎的叶绿素含量、光合特性参数、灌浆速率和粒重进行了比较研究。结果表明,旗叶先衰型小麦异常茎的叶绿素含量、蒸腾速率、净光合速率在结实期的一定阶段呈现倒二叶超越旗叶;异常茎上的根、茎、叶较正常茎发育充分且较为发达,其灌浆速率也比正常茎快,因而一些重要农艺性状较正常茎为优。上述表型的出现可能与特殊的灌浆机制相关,不同于正常小麦旗叶作为向籽粒输送养分的主源于结实全程发挥作用的模式,并最终造成它们的籽粒体积、千粒重和穗粒重分别比正常小麦高9.64%、10.35%和8.43%。对这类小麦的深入研究有助于完善小麦生长发育、灌浆结实以及衰老机制理论,促进小麦产量的进一步提高。

英文摘要：

A type of wheat has been discovered by the long time observation that the flag leaf senesces earlier than second and third leaves from top, differing from the conventional understanding for leaf senescing sequence in the majority of wheats. To reveal the biological characteristics of the type of wheat and its possible utilization in theoretical study and practice, we carried out an experiment of the type of wheat with presenile flag leaf, using normal wheat as the control in 2005-2011. The results showed that ： in the type of wheat with presenile flag leaf, the leaf chlorophyll content, transpiration rate and net photosynthetic rate were higher in the penultimate leaves, the roots, stems, and leaves were more developed, its grain filling rate was faster, and some important agronomy traits caused by above-mentioned factors were excellent, as compared with normal wheat. The grain volume, 1000-grain weight and weight of grain per spike of this type of wheat were 9.64%, 10.35%, and 8.43% higher than those of the normal wheat, respectively, and this may be closely related to the special grain filling mechanism differing from that of the normal wheat whose flag leaves work as the main nutrient sources for grain filling in the whole fruiting process. This study provided an new approach to research wheat growth, fruiting and senescence theory, further increasing wheat yield.