不同秧苗素质和移栽密度条件下臭氧胁迫对水稻光合作用、物质生产和产量的影响

近地层臭氧浓度升高使水稻生长受抑进而使产量下降,但这种影响是否因不同栽培条件而异尚不清楚。2011年依托先进的稻田臭氧FACE(Free Air gas Concentration Enrichment)技术平台,以汕优63为供试材料,臭氧设置大气臭氧浓度(Ambient)和高臭氧浓度(比Ambient高50%),秧苗素质设置弱苗(移栽时无分蘖)和壮苗(移栽时带两个分蘖),移栽密度设置低密度(16穴/m2)、中密度(24穴/m2)和高密度(32穴/m2),研究不同秧苗素质和移栽密度条件下臭氧胁迫对水稻生长和产量的影响。结果表明:高浓度臭氧使水稻结实期叶片SPAD值、净光合速率、气孔导度和蒸腾速率明显下降,但胞间CO2浓度和叶温无显著变化。高浓度臭氧对水稻拔节前物质生产量没有影响,但使拔节至抽穗期、抽穗至成熟期物质生产量平均分别降低13%和29%,进而使成熟期生物产量和籽粒产量均显著下降。方差分析表明,臭氧与秧苗素质间没有互作效应,但臭氧与移栽密度的互作对最终产量的影响达显著水平。以上结果表明,臭氧胁迫使水稻生长后期光合受阻,导致物质生产和产量显著下降;适当增加移栽密度可能会减少臭氧胁迫下水稻产量的损失。

Effects of ozone stress on photosynthesis, dry matter production and yield of rice under different seedling quality and plant density

Rising tropospheric ozone concentration constrained plant growth and thus result in yield loss of rice. However little is known about response of growth and yield of rice to elevated ozone concentration under different cultivation measures. By using an advanced FACE (Free Air gas Concentration Enrichment) system, hybrid rice cultivar shanyou 63 was grown at ambient (A-O₃) and elevated ozone concentrations (E-O₃,ambient×1.5). At transplanting, week seedlings (no tillers) and robust seedlings (with 2 tillers) were selected and planted with 3 spacing levels: low plant density(16 hills/m²), medium (24 hills/m²) and high plant density(32 hills/m²). Results showed as follows: Ozone stress decreased the SPAD value, net photosynthetic rate (P_n), stomatal conductivity (G_s) and transpiration rate (T_r) of flag leaves, but there was no significant effect on intercellular CO₂ concentration(C_i) or leaf temperature(T_l). There was no significant ozone effect on dry matter production before jointing stage. However, elevated significantly reduced dry matter production from jointing to heading stage and from heading to maturity stage by 13% and 29%, respectively. As a result, reduced dry matter accumulation at maturity stage and significant yield reduction were observed at harvest. The analysis of variance showed that seedling quality by O₃ interaction was not significant, but significant interactions were detected between O₃ and plant density for yield. The above results indicate that ozone stress significantly inhibited photosynthesis of rice during late growth stage, which result in reduced dry matter production and yield loss of rice. Ozone-induced yield loss could be mitigated by appropriately increasing plant density.