| 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(Fv/Fm), net photosynthetic rate(Pn), transpiration rate(Tr), 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 Fv/Fm, Pn and Tr 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, Fv/Fm, Pn and Tr. 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, Pn, Tr and Fv/Fm, 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. |
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