水稻根系生长发育对CO2浓度升高的响应及其品种间的差异

Minirhizontrons是一种非破坏性、定点、可直接观测和研究植物根系的新方法。利用微根管Minirhizotrons在试验田的温室大棚内研究CO2浓度升高作用下的水稻根系生长发育，试验采用完全随机处理，探讨CO2浓度升高（800μmol·mol-1）对水稻（Oryza sativa L.）生物量和根系形态的变化差异。结果表明，与CO2对照相比，CO2浓度升高显著增加4个水稻品种（2种杂交籼稻和2种常规籼稻）的地上部生物量，增幅为8.58%-12.66%，平均增加10.61%。CO2浓度升高条件下，根的生物量分别增加了3.16%-12.13%，平均增加8.64%。高CO2浓度对根系形态的影响表明，4种水稻根系对CO2浓度升高都有积极的响应。CO2浓度升高条件下，各根系指标在水稻不同生育期都有显著增加，根长密度、表面积、体积和根数的平均增幅分别为10%-27%、21%-24%、20%-58%和4%-18%。但在水稻生长发育过程中，品种间也存在着差异。CO2浓度升高和对照处理，籼型杂交稻威优644（V644）和金优207（JY207）的根长密度和根数表现出相似的变化趋势；高CO2浓度处理时其根长密度平均都增加了10%，根数平均增加4%和8%。CO2浓度升高和对照处理，2种籼型杂交水稻的根体积和表面积表现出较快的增长幅度，都呈现出近线性的生长趋势；CO2浓度升高处理下其根体积平均增加40%和25%，表面积平均都增加了24%。CO2浓度升高和对照处理，籼型常规稻湘晚12号（XW12）和丰华占（FHZ）的生长变化趋势表现一致，生长发育后期达到一个近似饱和的拐点。CO2浓度升高条件下其根长密度、根数和根体积分别平均增加27%和24%、18%和11%、58%和20%，根表面积平均都增加了21%。

Response of root development on elevated CO2 and its variation among different rice varieties

Mimirhizotrons is a non-destructive, fixed-point, in situ method for directly viewing and studying plant root dynamics. The minirhizontrons for studying biomass and root morphology variation of rice （Oryza sativa L.） in the field of greenhouse were employed in the study. Completely randomized design was used. The results showed that, the aboveground biomass of four rice varieties （two indica hybid and two indica convention） increased significantly from 8.58% to 12.66% （mean value 8.64%） with elevating CO2 concentration. There were positive effects on root length density, surface area, volume, and tips number at four growth stages （tillering, heading, grain filling period, and ripening period） of rice varieties with elevated atmospheric CO2. The ranges of root length density, surface area, volume, and tips number were 10%-27%, 21%-24%, 20%-58%, and 4%-18%, respectively. There were significant differences among rice varieties during rice root growth with CO2 treatment. The root length density and tips of indica hybrid rice varieties （V644 and JY207） showed the similar trends in the rice growth periods, the mean percentages of root length density and tips increased by 10%, 10%, and 4%, 8%, respectively. The average values of root volume and surface area of V644 and JY207 were up to 40%, 25%, and 24%, 24%, respectively, indicating linear growth trend. The indica convention rice XW12 and FHZ had the same growth trend, while the increase rate of root growth parameters was relatively gentle and reached an approximation saturation point at the late growth stage of rice. Under CO2 treatment condition, the four root parameters （root length density, tips, volume, and surface area） of XW12 increased 27%, 18%, 58%, and 21%, ,and of FHZ were up to 24%, 11%, 20%, and 21%, respectively.