大气CO_(2)浓度升高对高、低响应水稻品种根系生长的影响——FACE研究

Effects of Elevated Atmospheric CO_(2)Concentration on Root Growth of“Strong”and“Weak”Response Rice Varieties:A FACE Study

大气CO_(2)浓度([CO_(2)])升高是未来气候变化的主要特征之一,研究表明高[CO_(2)]会提高水稻产量,且水稻两个亚型(籼稻和粳稻)的产量增幅存在很大的差异。然而,目前还不明确这种基因型的响应差异是否与其根系的生长响应差异有关。本试验依托自由大气[CO_(2)]升高研究平台(free air CO_(2)enrichment,FACE),以低产量响应品种粳稻(Oryza sativa L.japonica)武运粳23和高产量响应品种籼稻(Oryza sativa L.indica)扬稻6号为试验材料,设置高[CO_(2)](590μmol/mol)和对照(390μmol/mol)处理。使用微根窗法连续动态检测两种水稻的根系生长状况,进一步计算根系周转率指标。结果表明:高[CO_(2)]显著促进了两个品种的水稻根系生长,其根系长度、表面积和体积相对于对照平均增加了120%、106%和98%;两个品种间,高[CO_(2)]处理使武运粳23的根系周转率显著下降,降幅达66%;扬稻6号的根系周转率则上升了约18%;高[CO_(2)]处理下的武运粳23的根系增量主要分布在浅层(32%升至56%),而扬稻6号的根系在深层的分布从12%增加至20%。结合已有产量响应及氮素吸收结果,我们认为相较于根长等根系形态指标,水稻根系的周转率与深层根系分布比例可能是不同基因型水稻品种的产量对高[CO_(2)]响应存在明显差异的主要原因。

As one of the main scenarios of future climate change,studies have shown that high atmospheric concentration CO_(2)([CO_(2)])will promote rice yield and the yield increase varies greatly between two rice subspecies(indica and japonica).However,there is still a knowledge gap on whether the yield response difference between subspecies is related to root growth.Here we conducted a FACE(free air CO_(2)enrichment,FACE)experiment using“weak”(Oryza sativa L.japonica,Wuyungeng 23)and“strong”(Oryza sativa L.indica,Yangdao 6)yield responsive varieties,elevated[CO_(2)](590μmol/mol)and control(390μmol/mol)treatments were set.Minirhizotrons were used to detect the root growth status of the two varieties continuously and dynamically,and the root turnover rate was further calculated.The results showed that elevated[CO_(2)]significantly enhanced the growth of rice roots of the two varieties,and the root length,surface area and volume across two varieties were increased by 120%,106%and 98%on average compared to the control,respectively.The root turnover rate of Wuyungeng 23 was significantly reduced by 66%under elevated[CO_(2)],the root turnover rate of Yangdao 6 increased by around 18%.For Wuyungeng 23,most of the root increased by elevated[CO_(2)]was mainly distributed in the shallow layer(32%to 56%),however,the root distribution of Yangdao 6 in the deep layer was increased from 12%to 20%by elevated[CO_(2)].Combination with the yield response and aboveground nitrogen uptake,we concluded that compared to root morphological indicators such as root length,the turnover rate of rice root system and the distribution ratio of deep root system may be the main reason for the obvious difference in the response of indica and japonica rice to elevated[CO_(2)].