FACE对武香粳14颖花分化和退化的影响

Effect of Free-air CO_2 Enrichment on Spikelet Differentiation and Degeneration of Japonica Rice(Oryza sativa L.) Cultivar Wuxiangjing 14

2001—2003年，利用我国唯一的农田开放式空气c02浓度增高（FACE）研究平台，研究大气c02浓度比对照高200μmol·mol^-1的FACE处理对水稻品种武香粳14颖花分化和退化的影响。FACE处理结果表明，每穗现存颖花数平均比对照少10．4～12．6朵，降幅为6．88％～8．49％，达极显著水平；对每穗颖花分化数和1次枝梗颖花退化数无显著影响，但使2次枝梗颖花的退化数和退化率显著高于对照；水稻每朵分化颖花所占有的抽穗期植株含N量和拔节至抽穗期的吸N量显著或极显著小于对照，使抽穗期茎鞘中可溶性碳水化合物含有率及其与植株含N率的比值显著或极显著高于对照；每朵分化颖花所占有的抽穗期植株含N量和拔节至抽穗期的吸N量与每穗颖花退化数均呈线性负相关，相关系数分别为-0．848^＊＊、-0．961^＊＊;抽穗期茎鞘中可溶性碳水化合物含有率及其和植株含N率的比值与每穗颖花退化数均呈线性正相关，相关系数分别为0．808^＊、0．831^＊。认为FACE处理降低水稻颖花形成期吸氮能力，使植株碳代谢增强、氮代谢减弱可能是其分化颖花大量退化和每穗颖花数少于对照的重要原因之一。

The experiment was conducted at Anzhen city, Wuxi, Jiangsu, China, to study the effect of free-air CO2 enrichment [ FACE, 200μmol· mol^-1 higher than ambient（AMB）] on spikelet differentiation and degeneration, using the japonica cultivar Wuxiangjing 14, in 2001-2003. Results of FACE treatment showed that the survived spikelets per panicle have decreased by 10.4 to 12.6, i.e. 6.88% to 8.49%. There were no significant effects on the differentiated spikelets per panicle and the degenerated spikelets of the primary branches per panicle, while an increase of the number and percentage of spikelets degenerated on the secondary branches per panicle compared with those under AMB; the plant N accumulation per differentiated spikelet at heading and N absorption per differentiated spikelet from stem elongating to heading were significantly lower, whereas the content of soluble carbohydrates in stem and sheath at heading and the ratio of that to nitrogen content in rice plant were significantly higher compared with those under AMB ; the degenerated spikelets per panicle negatively and significantly correlated with the N accumulation per differentiated spikelet at heading （-0.848^＊＊） and with the N absorption per differentiated spikelet from elongating to heading （ - 0.961^＊＊ ）, respectively; While the degenerated spikelets per panicle positively and significantly correlated with the content of soluble carbohydrates in stem and sheath （0.808^＊） and with the ratio of the soluble carbohydrates content in stem and sheath to nitrogen content in rice plant at heading stage （0.837^ ＊ ）, respectively. It was speculated that the ability of N absorption weakened, carbon metabolism strengthened and nitrogen metabolism weakened due to FACE during the period of spikelets formation, were the primary causes of largely degenerating number of differentiated spikelets and decreasing number of spikelets per panicle under FACE condition.