CO_(2)浓度升高下水稻株高、茎蘖与SPAD动态响应及其模拟

Dynamic Response of Rice Plant Height, Tillering and SPAD under Elevated CO_(2) Concentration and Their Simulation

水稻是中国主要粮食作物,CO_(2)浓度升高直接影响水稻的生产。但在CO_(2)浓度升高条件下,水稻生长发育的动态特征及其模型模拟研究尚不足。为探究水稻株高、分蘖与SPAD(表征叶绿素相对含量)动态对CO_(2)浓度升高的响应特征,在2017年与2018年,以常规粳稻“南粳9108”为试验材料,利用开顶式气室(OTC),设置背景大气CO_(2)浓度与CO_(2)浓度升高(+200μmol·mol^(-1))两个处理,并采用Logistic方程、Logistic修正方程和多项式回归方程分别对三者的动态曲线进行定量描述。结果表明:CO_(2)浓度升高对抽穗前的株高无影响,但当抽穗1周后的有效积温(GDD)大于720℃·d时,显著增加了最终株高,其增幅为7.1%(P<0.05)。因此,水稻生长的环境温度调控株高对CO_(2)浓度升高的响应。株高可用大于10℃的GDD和CO_(2)响应比建立的Logistic方程进行有效模拟(r~2>0.953)。CO_(2)浓度升高总体上提高了水稻的分蘖能力,并且以移栽后天数和CO_(2)响应比为驱动变量,采用Logistic修正方程有效地模拟了茎蘖增长与消亡动态(r~2>0.971)。CO_(2)浓度升高仅增加了2017年抽穗后35 d旗叶与倒二叶的SPAD(P<0.05),但对其他时期或叶位SPAD无显著影响。因此,水稻SPAD对CO_(2)升高的响应因叶位选择与测定时间而异。多项式回归模型能有效模拟抽穗后不同叶位SPAD动态(r~2>0.960),其中抽穗后天数和CO_(2)响应比是驱动变量。综上所述,CO_(2)浓度升高对水稻株高、茎蘖与SPAD具有促进作用,其效应与外界因素有关。模型能较好地模拟水稻株高、茎蘖与SPAD对CO_(2)浓度升高的动态响应。该研究可为未来CO_(2)浓度升高条件下,水稻生长发育和产量形成的预测提供科学依据。

Rice is the main cereal crop in China,and elevated CO_(2) concentration(e[CO_(2)])directly affects the production of rice.However,research on the dynamic characteristics of rice growth and development and their simulation under the condition of e[CO_(2)]is still insufficient.To investigate the dynamic responses of plant height,tillering and SPAD(characterizing the relative content of chlorophyll)to e[CO_(2)]in rice(Oryza sativa L.).A conventional Japonica rice variety,“Nangeng 9108”,was cultivated under two CO_(2) levels―ambient CO_(2) concentration and e[CO_(2)](+200μmol·mol-1)using open-top chamber(OTC)in 2017 and 2018.Dynamic curves of the height,tillering and SPAD of rice were quantified by using the logistic equation,logistic modified equation and polynomial regression equation,respectively.The results showed that e[CO_(2)]did not affect plant height before the heading stage.However,when the growing degree day(GDD)was greater than 720·℃d,the final plant height increased by 7.1%(P<0.05)one week after heading.Thus,the response of plant height to e[CO_(2)]was regulated by the environmental temperature of rice growth.The plant height was effectively modeled by the GDD above 10℃and CO_(2) response ratio using the logistic equation(r2>0.953).Generally,e[CO_(2)]enhanced the tillering ability of rice.The tiller growth and extinction dynamics were effectively simulated using the logistic modified equation(r2>0.971),with the days after transplanting and CO_(2) response ratio as driving variables.The e[CO_(2)]increased the SPAD of the flag leaf and second leaf,thirty-five days after heading in 2017(P<0.05),but had no effect on SPAD of other periods and leaf position.Thus,the response of rice SPAD to e[CO_(2)]varied with the measured time and leaf position.The dynamic curves of SPAD of different leaf position could be effectively simulated by polynomial regression model(r2>0.960),with days after heading and CO_(2) response ratio as driving variables.In summary,e[CO_(2)]can promote the plant height,tillering and SPAD in rice,and the effect is affected by external factors.The models can effectively simulate their dynamic response to e[CO_(2)].Our study can provide a scientific basis for predicting the growth,development and yield formation of rice under of e[CO_(2)]in future studies.