Studies On Differences Of Photosynthetic Characteristics Among Different Green Photosynthetic Organs In Seed Production Population Of Hybrid Rice

Hybrid rice seed production is different from conventional rice production, the rice population quality and construction groups in seed production plot has had a fundamental change, such as maternal plant height increased, spike layer exposed, and leaf layer down, etc. At the same time the effective leaf area dropped sharply since the leaf layer of female parent should located down its panicle layer, and especially the top3leaves must shorten in case of obstacle the pollination. Above which have important influence on aboveground dry matter production and transportation for seed production, and further affect the seed yield. This study was aimed to find out the photosynthetic differences of different hybrid rice seed production populations. Field trial was carried out with two nitrogen fertilizer models as main plot and four Gibberellin concentration as split plot and Ⅱ you416was used as the target combination (Ⅱ-32A&R416as female and male parent respectively) in Liuyang county in2013. In this study the chlorophyll contents, chlorophyll fluorescence characteristics, the activity of photosynthetic enzyme, isotopic14C tracing and the photosynthetic product contribution rate from different green organs were measured to find out the photosynthetic characteristics difference of different photosynthetic organs and their effects on seed production yield. The key outcomes of this study were as follows.1.The chlorophyll contents of different green photosynthetic organs include leaf, panicle and leaf sheath in different hybrid rice seed production were measured and the results showed that leaf>sheath>panicle. With the advance of growth and development, the chlorophyll contents in leaf and sheath decreased, however the contents in panicle reduced slowly, which maintain the photosynthetic function in the late stage and contributed to the accumulation of dry matter.2.The key photosynthetic enzyme in leaf, panicle and sheath in different hybrid rice seed production populations were measured and the results showed that there was always the key enzyme PEPCase of C4way in all the stage after full heading, which indicated that the key enzyme PEPCase had a supplement role in the photosynthesis of hybrid rice seed production. 3.The chlorophyll fluorescence parameters of the flag leaf, sheath and panicle were measured by mini-PAM and the results showed that NPQ showed panicle>sheath and leaf, which indicated that the photosynthetic organs of panicle had a higher ability to dissipate surplus solar energy. While qL showed leaf>sheath and panicle, which indicated that panicle had a lower degree of opening in reactive center of PS Ⅱ in the photosynthesis process.4.In the experiment of isotopic tracing, the results showed that most of the photosynthetic products of the green panicle provided to the seed and half of the photosynthetic products of the flag leaf provided to the seed. Spraying Gibberellin is beneficial to the transfer and distribution of photosynthetic products to the panicle.5.In the experiment of cutting leaf, wrapping stem and panicle and taking samples in mature stage, the results showed that there was significant difference among different green organ in the photosynthetic contribution rate. The photosynthetic contribution of panicle and leaf and stem are respectively29.7%-62.3%、34.3%-39.7%and0-30.7%, which reflected that non-leaf photosynthesis had a important role in the yield of seed production.