冬前镇压和灌溉对冬小麦灌浆期旗叶光合特性和叶绿体超微结构的影响

为明确冬前镇压和灌溉对冬小麦灌浆期旗叶功能的影响,以济麦22为材料,在2016-2017小麦生长季,对其进行冬前镇压+灌溉(C+I)、灌溉(I)和镇压(C)处理,以常规种植管理为对照(CK),研究不同冬前栽培措施对冬小麦灌浆期土壤微环境、旗叶光合特性和叶绿体超微结构以及最终产量和生物量的影响。结果表明,与CK相比,C、I及C+I处理都可提高麦田土壤含水量和土壤温度,可增加花后14～28d旗叶叶绿素相对含量(SPAD)、灌浆期旗叶最大光学效率(Fv/Fm)、净光合速率(Pn)和蒸腾速率(Tr),缓解旗叶SPAD、Fv/Fm、Pn和Tr在灌浆后期的下降,其中以C+I处理的效果最佳;灌浆中后期(花后21d),CK条件下小麦植株旗叶部分叶绿体呈圆形,大部分基粒片层变形且排列紊乱,可见较多的亲锇颗粒,但C+I、C和I处理下叶绿体的破坏程度降低,较多的叶绿体呈椭圆形,单位面积内叶绿体数和叶绿体基粒数提高,基粒片层较CK清晰且排列紧密,亲锇颗粒数量减少,其中C+I和I处理对叶绿体超微结构的改善作用大于C处理。这说明在本试验条件下,冬前镇压+灌溉较单独灌溉或镇压更有利于改善小麦灌浆期旗叶光合功能,缓解灌浆后期旗叶的衰老,促进小麦产量形成。

Effects of Pre-Winter Compaction and Irrigation on Photosynthetic Characteristics and Chloroplast Ultrastructure of Flag Leaf at Grain Filling Stage of Winter Wheat

In order to clarify the effects of pre-winter compaction and irrigation on the function of flag leaf at grain filling stage of winter wheat, a field experiment was carried out during the wheat growing season of 2016-2017, and pre-winter compaction and irrigation(C+I), irrigation(I) and compaction(C) were applied to the winter wheat Jimai 22. With the normal growing plant as the control(CK), and the chlorophyll content(SPAD), maximum photochemical efficiency(F_v/F_m), net photosynthetic rate(P_n), transpiration rate(T_r), chloroplast ultrastructure during grain filling stage and the final yield were analyzed. The result showed that water content and temperature of the soil during the late grain filling stage were all increased under C+I, I and C treatments, among which, the maximum increment was achieved under C+I. The SPAD in the flag leaf was higher during the late grain filling stage(14-28 days after anthesis(DAA)) under the C+I and C treatments than that under I and CK treatments. The F_v/F_m, P_n and T_r of the flag leaf during the whole grain filling period showed highest under C+I treatment, followed by those under I and C treatments. C+I, C or I can relief the reduction of SPAD, F_v/F_m, P_n and T_r. Among them, C+I treatment showed the most effect. Under the control conditions, the chloroplast of flag leaf was circular, and most of the grana lamellaes were deformed and disorderly arranged and a lot of osmiophilic granules appeared at 21 DAA. However, under the C+I, C and I treatments, the chloroplasts was ellipsoidal, and the number of chloroplasts and chloroplasts grana were significantly higher than those under CK treatment, and the grana lamellaes were clear and tightly packed, with a much less number of osmiophilic granules. The damage degree of chloroplasts in the flag leaf was decreased under C+I, C and I treatments. Based on the result of the SPAS, P_n, T_r and F_v/F_m, the C+I treatment in this experiment was more conducive than C, I and CK treatments by improving the photosynthetic function of flag leaf during grain filling and alleviating aging of flag leaves at late grain filling stage. Thus, C+I treatment is more conducive to improve wheat production.