Abstract:

This study was designed to research the photosynthetic capacities of the flag leaf sheathes and photosynthetic products’ distribution of the leaf sheathes of Liangyoupeijiu, using Liangyoupeijiu (super hybrid rice), its parents 9311, Pei’ai 64S and Shanyou 63 (three-line hybrid rice combination) by the isotopic labeling and other techniques. The results showed that the mean of the Pn of the flag leaf sheathes for Liangyoupeijiu was 0.10 µmolCO₂.m^-2.s^-1 higher than that for Shanyou 63, and it was significantly higher at the third stage which was the key period of rice profuse filling, while it was not at other stages. The mean of the chlorophyll content of the flag leaf sheathes for Liangyoupeijiu was 2.26 SPAD value higher than that for Shanyou 63, and it was higher at every stage, and significantly higher at the first and the third stages. There was no significant difference in Rubisco incipient activities and total activities between the flag leaf sheathes of Liangyoupeijiu and those of Shanyou 63. Rubisco activated percentage mean of the flag leaf sheathes for Liangyoupeijiu was 1.52% higher than that for Shanyou 63, and Liangyoupeijiu had mean potence. At the third stage, that for Liangyoupeijiu was significantly higher than that for Shanyou 63. The transportation of photosynthate to the spikes of all leaf sheathes for Liangyoupeijiu was more and quicker than that for Shanyou 63, leading to more economic yield for Liangyoupeijiu than for Shanyou 63. The photosynthetic capacity mean of the flag leaf sheathes for Liangyoupeijiu was of the mean potence or heterobeltiosis as comparison with that for its parents. Rice leaf sheath had completely the same kind of photosynthesis as comparison with rice leaf blade but their quantitive difference. The photosynthate of rice leaf sheath transported mostly to its spikes, blades etc, and the contribution to yields was between 10% and 20%. The strong photosynthetic function of both the sheath and blade is one of the main reasons why Liangyoupeijiu is of super high yield.

Key words: Super Hybrid Rice, Liangyoupeijiu, Flag leaf, Sheath, Photosynthetic Function