FACE条件下水稻生育后期剑叶光合色素含量及产量构成的响应研究

Responses of flag-leaf photosynthetic pigments at late growth stage and rice yield components to elevated CO_2 under FACE system

为明确CO2浓度增高对水稻叶片光合能力的影响,利用自由CO2富集系统(free-air carbon dioxide enrichment,FACE)研究‘松粳9号’和‘稻花香2号’水稻生育后期剑叶光合色素含量及产量构成的变化趋势;通过测定水稻孕穗—抽穗期剑叶叶绿素a、叶绿素b和类胡萝卜素含量,分析光合色素组成、各组分间相关关系及品种间差异;收获后实测产量构成因素,比较处理及品种间差异。结果表明,与对照相比,高CO2浓度下水稻孕穗和抽穗期叶绿素a含量都极显著升高,‘松粳9号’和‘稻花香2号’的最大增幅分别达28.46%和19.58%;抽穗后20 d分别极显著降低15.25%和23.20%。高浓度CO2极显著降低水稻抽穗后20 d叶绿素b含量,两品种降幅分别为7.57%和5.33%;极显著增加抽穗后30 d叶绿素b含量,增幅分别为4.19%和9.46%。高CO2浓度下两品种水稻抽穗期类胡萝卜素含量显著增加9.47%和13.55%,抽穗后10 d之后显著降低,最高降幅达13.54%和16.67%。高CO2浓度下水稻总叶绿素含量和叶绿素a/b比值在孕穗和抽穗期增加,抽穗后20 d减少。高CO2浓度对产量构成因素均有正面影响,增加了水稻单位面积穗数、结实率和千粒重,显著提高了千粒重,两品种增幅分别达8.6%和4.5%。试验结果明确了高CO2浓度对水稻灌浆前期剑叶光合色素的积累有促进作用,后期有抑制作用,品种间响应差异显著;千粒重增加是增产的主要因素。

To verify the effects of elevated atmospheric CO2 concentration on photosynthetic capacity of rice leaves, the trend in photosynthetic pigments contents of flag-leaves at late growth stage and yield components of rice varieties of ‘Songjing9’ and‘Daohuaxiang2’ were studied under the free-air CO2 enrichment （FACE） system. Flag-leaf chlorophyll-a, chlorophyll-b and carotenoid contents were measured during booting and heading stages and yield components measured after harvest. The total chlorophyll content and the ratio of chlorophyll-a to chlorophyll-b were calculated and the correlations among yield components analyzed. The results showed that comparing to ABM （ambient CO2） treatment, FACE treatment increased chlorophyll-a contents in flag-leaves of both rice varieties at booting to heading stage with respective peak increasing values of 28.46% and 19.58%, and decreased by 15.25% and 23.20% at 20 d after heading stage. FACE treatment decreased chlorophyll-b contents of flag-leaves of both rice varieties by 7.57%and 5.33%at 20 d after heading stage, then increased at respective rates of 4.19%and 9.46%at 30 d after heading stage. Carotenoid contents in flag-leaves of both rice varieties noticeably increased respectively by 9.47% and 13.55% at heading stage under FACE treatment and then decreased at 10 d after heading stage at rates of 13.54%and 16.67%. The trends in the effects of elevated CO2 concentration on total chlorophyll content and chlorophyll-a to chlorophyll-b ratio of flag-leaf were similar. The trends increased from booting to heading stage and then decreased at 20 d after heading stage. Elevated CO2 concentration was beneficial to yield components by increasing spike number per unit area, seed-setting rate and 1000-grain weight. The 1000-grain weight was increased by 8.6% and 4.5% of the two varieties, respectively. The results suggested that while elevated atmospheric CO2 concentration enhanced photosynthetic pigment accumulation in flag-leaves of rice at booting and heading stages, it inhibited photosynthetic pigment accumulation after heading stage. Photosynthetic pigments of flag-leaves of different varieties of rice had different degrees of responses to elevated atmospheric CO2 concentration. Increased 1000-grain weight was the key factor for yield increase of rice under elevated atmospheric CO2 concentration.