杂交小麦苗期光合特性分析及其对强优势组合的早期预测

【目的】通过分析不同杂交小麦组合及其亲本苗期叶片的光合特性与籽粒产量的相关性,为杂交小麦强优势组合早期筛选和预测提供理论依据。【方法】以2个恢复系和4个不育系及其配制的6个杂交小麦组合为材料,在大田种植条件下测定小麦苗期叶片的光合特性,包括净光合速率(P_n)、气孔导度(Gs)、胞间CO2浓度(Ci)、蒸腾速率(T_r)、水分利用效率(WUE)、叶绿素含量、Rubisco活性及其大小亚基编码基因rbcL、rbcS相对表达量;调查成熟期的产量性状,包括株高、主穗穗长、单株地上生物量、有效穗数、穗粒数、单株籽粒产量、主穗小穗数、千粒重、收获指数,并分析杂种优势以及光合性状与产量性状的相关性。【结果】杂交小麦苗期的净光合速率、气孔导度、蒸腾速率均表现出显著的超高亲优势,其中净光合速率的平均超高亲优势为15.4%,气孔导度为21.3%,蒸腾速率则为11.46%,净光合速率值高的恢复系所配制的杂交组合具有更高的净光合速率和杂种优势,而胞间二氧化碳浓度、水分利用效率则少数有负向优势。成熟期有效穗数、单株籽粒产量及单株生物量具有较高的超高亲优势,其中穗数的超高...

Analysis of Photosynthetic Characteristics of Hybrid Wheat at Seedling Stage and Its Use for Early Prediction of Strong Heterosis Combinations

【Objective】The aim of this study was to provide a theoretical basis for early heterosis prediction of hybrid wheat by analyzing photosynthetic characteristics of leaves of different hybrid wheat combinations and their parents at the seedling stage, so that it was easy to select hybrids with strong heterosis. 【Method】 Six hybrid wheat combinations and their parents, including two restorer lines and four male sterile lines, were used as materials to measure the photosynthetic characteristics of wheat leaves at the seedling stage in the field, including net photosynthetic rate (P_n), stomatal conductance (G_s) and intercellular CO₂ concentration (C_i), transpiration rate (T_r), water use efficiency (WUE), chlorophyll content (Chl.), Rubisco content and the relative expression of rbcL and rbcS genes encoding Rubisco subunits as well as their heterosis and correlation. The yield traits were investigated at the wheat maturity stage, including plant height, length of main spike, biomass per plant, spike number per plant, grains per spike, grain yield per plant, spikelets of main spike, thousand grain weight, and harvest index. And then, correlation between grain yield and their photosynthetic characteristics was analyzed. 【Result】 P_n, G_s and T_r of six hybrid wheat showed significant heterosis over high parents. The average heterosis of P_n over high parents was 15.4%, G_s was 21.3%, and T_r was 11.46%. The higher P_n and stronger heterosis of hybrids resulted from the restorer lines with higher P_n, while C_i and WUE of some hybrids showed negative heterosis. The number of spikes per plant, yield per plant and biomass per plant had greater heterosis over high parents, in which the number of spikes per plant performed the highest heterosis with 34.21% on average. Correlation analysis showed that P_n was significantly or super-significantly positively correlated with G_s, T_r, grain yield per plant and biomass per plant, suggesting that G_s and T_r could help to screen high photosynthetic wheat, and P_n at the seedling stage had important relationship with yield. Among them, the Rubisco activity of hybrid wheat was higher than that of its parents, and it had a significant heterosis over high parents, with an average heterosis of 5.38% over high parents. Compared with rbcL, rbcS had a higher over high-parent heterosis and over mid-parent heterosis. The chlorophyll content mainly showed a negative advantage, few over mid-parent heterosis, and very few showed over high-parent heterosis. There was no significant correlation between P_n and other photosynthetic characteristics.【Conclusion】 The results indicated that the leaf photosynthesis of hybrid wheat at the seedling stage showed significant over high-parent heterosis, especially P_n, G_s and T_r, and P_n was significantly positively correlated with the yield per plant and the biomass per plant, so the level of net photosynthetic rate could be one of the important traits for early prediction of yield potential of hybrid combination.