【作者】 曾斌； 许晓明； 周世象； 朱春生； 唐灿明；

【机构】 南京农业大学农学院； 南京农业大学生命科学院； 湖南棉花研究所；

【摘要】 本文的目的是研究陆地棉杂交种湘杂棉3号的光合速率杂种优势日变化及其与环境的关系。以中国长江流域大面积推广的棉花杂交种湘杂棉3号正、反交杂种及其亲本为材料,对各材料花铃期主茎功能叶的净光合速率日变化规律和不同温度下光响应特征进行测定。主要结果是:（1）湘杂棉3号正交F₁、反交F₁和父本、母本的净光合速率均在上午10:00达到最大值。10:00—12:00净光合速率明显下降。净光合速率下降与大气相对湿度降低、气温升高和叶片蒸汽压亏缺有密切关系。（2）正交F₁、反交F₁的净光合速率最大超亲优势分别为27.34%和43.13%,均出现在下午13:00—17:00,叶片处于高光强(>1000μmol·m^-2·s^-1)、高温（≥40℃）和低空气相对湿度（≤40%）等逆境条件下。（3）在高温（≥40℃）条件下,杂交种的叶片表现18.82%～251.85%的自降温超亲优势。杂交棉高温逆境条件下净光合速率优势表达与叶片自降温有关。（4）不同温度下的光响应结果表明,在1000μmol·m^-2·s^-1以下的光强下,杂交种的净光合速率在28℃、36℃、40℃3个温度下均没有超亲优势。在1000μmol·m^-2·s^-2以上光强下,杂交种的净光合速率超亲优势随温度升高而增大。在2000μmol·m^-2·s^-1光强和40℃条件下,正交F₁的净光合速率及其它光合参数超亲优势最大,反交F₁的净光合速率及其它光合参数超亲优势不显著。（5）正交F₁、反交F₁的气孔导度和蒸腾速率在36℃和40℃高温下的降低幅度小于亲本,表现超亲优势。（6）温度愈高,叶片的暗呼吸速率、光补偿点、光饱和点愈高,而最大光合速率和表观量子效率愈低。结论是:不同材料间的光合作用差异主要表现在高温、高光强等逆境条件下。对高温、高光强的抗性是湘杂棉3号杂交种杂种优势的基础而不是最大净光合速率。该结果对于揭示棉花杂种优势机理和提供一种新的培育高光效品种方法有重要意义。更多还原

【Abstract】 The objective of the study was to evaluate the diurnal variations of heterosis in photosynthetic rate of Xiangzamian3 and the relationship between the performance of heterosis and environment factors.The Xiangzamian3 reciprocal F₁ s and their parents were selected for study materials which were widely planted in the Yangtze River Valley of China.And the law of diurnal variations of heterosis in net photosynthesis rate of the 4th leaves from main stem top in one day and the character of photosynthesis responded to light under different temperatures were surveyed.The results showed that;（1）The maximum of the net photosynthetic rate（Pn）of all materials appeared at 10: 00.middle depression of Pn was observed obviously during 10:00—12:00,which correlated markedly with the reducing relative humidity（RH）,rising air temperature（Tair）and vapor pressure deficit（VPD）.（2）The maximum over better-parent heterosis（OH）in Pn of obverse F₁ and reverse F₁ was 27.34%and 43.13%respectively which was observed at afternoon during 13:00—17: 00,when under stress conditions with high light intensity(>1000μmol?m^-2?s^-1),high temperature （≥40℃）and low RH（≤40%）.The 18.82%to 251.85%OH exhibited in leaf temperature cooling which may be related with the expression of OH in Pn of hybrids under heat stress condition. （4）The results of Pn response to light under different temperatures also shows that no OH in Pn was observed in 28℃,36℃,40℃three temperature treatments but increased with temperature when light intensity was below 1000μmol?m^-2?s^-1.Moreover,both of the maximum OHs in Pn and photosynthetic parameters of obverse F₁ and reverse F₁ are observed with light intensity of 2000μmol?m^-2?s^-1and temperature of 40℃while the OH in photosynthetic parameters of reverse F₁ were no significant.（5）Under high temperature of 36℃and 40℃,stomatal conductance and transpiration rate of reciprocal F₁s had fewer reduced extent than parents and exhibited OH.（6）The higher the temperature,the higher the respiration rate of leaf in dark,light compensation point, light saturation point,while the lower the maximum photosynthetic rate and apparent quantum efficiency. Our conclusions were that;differences between the photosynthesis of different materials mainly exhibited under adverse conditions with high light intensity and high temperature.The resistance to high temperature and high light is the basis of heterosis,but not the maximum value in photosynthetic rate for Xiangzamian3 hybrids.And the results were significant to reveal mechanism of heterosis and provide a new path to select varieties with high net photosynthetic rate.更多还原