| In order to identify the photosynthetic potential of different plant parts in winter wheat, to improve yield and water use efficiency (WUE) simultaneously, the photosynthetic source change characteristics and ecological physiology mechanics were studied in population, individual and organ level at different development stage under water and fertilizer limited condition, especially non-leaf organs, i.e., ear, internodes, leaf sheath. And the genetic difference in photosynthetic capacity in different organs was also studied. In addition, by setting different plants density and irrigation treatments, some points were also focused on the culture technology principles of water saving and super high yield by establishing the population structure with higher density, smaller phylliform, higher photosynthetic capacity and lower water consumption.1. In the population of water-saving, fertilizer-reducing and high-yielding, green area of non-leaf organs was larger than leaf blade, which contributes much to yield. Non-leaf organs green area accounted for 60% of total green area per stem , and non-leaf area index (NAD was higher than leaf area index(LAI), the proportion of NAI in the total green area index( GAD increased gradually with reducing irrigation times or increasing plant density. Statistic analysis indicated that GAI and NAI post-anthesis were correlated positively with yield, and to obtain the yield with 7500~8250kg.hm-2 , the suitable LAI, highly active LAI and NAI of three uppermost leaves after anthesis was 4.81, 3.11, 6.86 respectively.; The water-saving and high-yield population in winter wheat had such primary structure characteristics as lower leaf area per stem especially smaller size upper leaf, higher specific leaf weight, smaller angular between flag leaf and stem, better light intensity in canopy, which could lead to higher canopy photosynthetic rate and WUE. By shading plant parts treatment, photosynthetic contribution of ear to grain yield was found higher greatly than that of flag leaf blade, and the total contribution of peduncle and sheath to grain yield was equal to leaf blade. Photosynthetic contribution of non-leaf organs above flag leaf node to grain yield accounted for 70%~ 80%,which increased with water supply decreasing or plant density increasing.2. There was obvious difference in stoma and chloroplast ultrastructure between leaf blade and non-leaf organ in winter wheat plant, chloroplast ultrastructure of non-leaf organs showed more stable compared with leaf blade in the late development stage under water-saving culture condition. Through electron microscopic, stomatal frequency and total stoma quantity of non-leaf organs was found lower than that of flag leaf. Stomata frequency of various organs increased with the decrease of water supply, but the total stoma number per organ did not increase. In stomata size, stoma of apparatus on the ear (glume, lemma,palea,awn) was a little smaller than that of other organs. With the decrease of water supply, stomatal aperture length of various organs increased, but the width of those decreased gradually. As to the stomatal distribution, stoma located mostly in the inner side(ventral or adaxial) of organs in ear, which could contribute to re-fixing CO2 released by grain respiration. The chloroplast ultrastructure was also observed, and the results showed that chloroplast number of non-leaforgans was lower than that of leaf blade, and many starch grains were found in the chloroplast of glume and lemma under normal water supply condition. The chloroplast structure of flag leaf blade and lemma was destroyed severely subjected to drought stress at the later stage of grain filling, while the peduncle, sheath and glume showed relatively stable.3. Under water-saving cultivation condition , PEPCcase activities and PEPC/RUBP ratio of non-leaf organs increased obviously, which increased the photosynthetic stress tolerance capability at the later grain-filling stage. There was significant difference in the photosynthet...
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