关键词：
rice;sheath;photosynthetic tissue;anatomical structure;mesophyllous cell;photosynthetic apparatus;stomatal density
摘要：
The photosynthesis of rice sheath plays a significant role to furnish rice yield, and it is accounted for 10 to 20% of the final yield. But, limited studies have been done to address this phenomenon and to characterize the features of the photosynthetic tissue in rice sheath. In this paper, a super hybrid rice and a hybrid rice were studied as the experimental materials, and the characteristics of the photosynthetic tissue in rice sheaths were examined by microscopic and super-microscopic observation. The results showed that the photosynthetic tissue of rice sheath was rich in the intact mesophyllous cells full of chloroplasts, grana and thylakoids, which were much the same as those of rice blade. The stomatal density in the outer epidermises of the sheaths was comparable to those in the up-and down-epidermises of the blades. The mesophyllous cells in the sheaths were also rich in chlorophylls, and had the net photosynthetic rate (Pn). Therefore, rice sheath was also full of the intact photosynthetic apparatus similar to those in rice blade, and had capabilities of photosynthesis.<br/>
摘要：
The photosynthesis of rice sheath plays a significant role to furnish rice yield, and it is accounted for 10 to 20% of the final yield. But, limited studies have been done to address this phenomenon and to characterize the mesophyllous cells of rice sheath and how it may attribute to the rice yield. In this paper, super hybrid rice Liangyoupeijiu, its parents Wumang 9311 and Peiai 64S, and hybrid rice Shanyou 63 were studied as the experimental materials, and the characteristics of the mesophyllous cells of rice sheaths were examined by microscopic and super-microscopic observation as well as chlorophyll absorption spectrums. The results showed that rice sheath was rich in the intact mesophyllous cells full of chloroplasts, grana and thylakoids, which were much the same as those of rice blade. The absorption spectrum curves of the Chl. a and b of the sheaths were similar to those of the blades. The stomatal density in the outer epidermises of the sheaths was comparable to those in the up- and down-epidermises of the blades. The significant tests proved that the amount of chloroplast per mesophyllous cell of the sheaths was almost the same as those of the blades, and the mesophyllous cells in the sheaths were also rich in chlorophylls. The chlorophyll content of rice sheath reached about 50% of the chlorophyll content of rice blade, and the Pn of the sheath/the blade ranged from 13.60 to 34.57%. Therefore, rice sheath was also full of the intact photosynthetic apparatus similar to those in rice blade, and had capabilities of photosynthesis. The statistical analysis revealed that the physiological senescence of the photosynthetic apparatus in both the sheath and the blade of Liangyoupeijiu was significantly slower than those of the other varieties at the late stages. The profuse grain-filling stage was an inflexion point of the physiological senescence of the chloroplasts and the chlorophylls of both the blades and the sheaths.
作者机构：
[李合松; 王若仲; 萧浪涛] Hunan Provincial Key Laboratory of Phytohormones and Growth Development, Hunan Agricultural University, Changsha 410128, China;School of Biological and Food Engineering, Changsha University of Science and Technology, Changsha 410076, China;[郭兆武] Hunan Provincial Key Laboratory of Phytohormones and Growth Development, Hunan Agricultural University, Changsha 410128, China<&wdkj&>School of Biological and Food Engineering, Changsha University of Science and Technology, Changsha 410076, China
通讯机构：
Hunan Provincial Key Laboratory of Phytohormones and Growth Development, Hunan Agricultural University, China
摘要：
Using high-yielding hybrid rice 'Liangyoupeijiu' (LYP9) and hybrid rice 'Shanyou 63' (SY63) as the experimental materials and using 14C radio-autography, the photosynthetic capacities and distribution of photosynthates in flag leaf blades and sheaths of LYP9 were studied. The results showed that net photosynthetic rates (Pn) of the flag leaf blades and sheaths of LYP9 were much higher than those of SY63; the light transmissivity rates (LT) measured at the medium height of the flag leaf sheaths and the penultimate leaf sheaths were also significantly higher than those of SY63. The incipient activities, total activities and activation percentages of Rubisco in the flag leaf blade and sheath of LYP9 were all higher than those of SY63. The photosynthate transport rate in the sheaths of LYP9, and the quantity of photosynthate transported to the spikes and transformed to economic yield of LYP9 were all higher than those of SY63. The photosynthates produced by the sheaths were mainly transported to spike to make a certain contribution (about 15%) to yield.
