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为了解水分亏缺下小麦穗部光合对产量的贡献，采用盆栽试验及¹⁴C 同位素示踪方法，研究了水分亏缺对不同抗旱性小麦花后穗部光合及穗光合产物向籽粒转运及产量的影响。结果表明，与正常供水处理相比，水分亏缺后，旱地品种西农1043灌浆前期穗部净光合速率、颖壳中可溶性总糖含量、籽粒¹⁴C 同化物分配率增加，而水地品种陕253均下降。收获后，水分亏缺显著降低了陕253颖壳及内外稃中光合同化物滞留率、籽粒产量和水分利用效率(P<0.01)，而对西农1043的影响不明显（P>0.05)。说明适度水分亏缺会提高旱地小麦灌浆前期穗部的碳同化能力，加速灌浆前期穗部光合产物向籽粒的转运，以维持一定的产量水平。

英文摘要:

A pot experiment with ¹⁴C isotope labeling technique was used to investigate the photosynthetic characteristics,accumulation and transportation of ¹⁴C assimilates of wheat ears during early grain filling stage under water deficit condition.The results showed that net photosynthetic rate of wheat ears,soluble sugar content of glumes and lemmas in dryland variety Xinong 1043 under middle water deficit were raised during early grain filling stage,while in irrigation land variety Shaan 253 fell into a reverse trend.¹⁴C isotope labeling experiments showed that the ¹⁴C assimilates of wheat ears was largely transported to the seed under water deficit in the mid grain filling stage.And accumulation of ¹⁴C assimilates in the seed of Xinong 1043 under middle water deficit (74.11%) was significantly higher than that of the control (64.61%),but ¹⁴C assimilates in the seed of Shaan 253 under middle water deficit (60.73%) was significantly lower than that of the control (69.75%).It indicated that middle water deficit can accelerate the transportation of ¹⁴C assimilates in ears of Xinong 1043 to the seed during early grain filling stage.Distribution of ¹⁴C radioactivity in glumes,lemmas and palea at harvest in Shaan 253 decreased under water middle deficit,but distribution of ¹⁴C radioactivity in Xinong 1043 changed insignificantly .Compared to the control,the yields and WUE of Xinong 1043 declined insignificantly under middle water deficit (P>0.05),but the yields and WUE of Shaan 253 declined significantly (P<0.01).It indicated that middle water deficit can improve both carbon assimilation of ears and transportation of photosynthetic of ears to the seed during early grain filling stage in dryland wheat variety to maintain the stability of yields.

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