臭氧胁迫对不同敏感型水稻生长和产量形成的影响

【目的】针对不断升高的近地层臭氧浓度,研究臭氧胁迫对不同敏感类型水稻生长动态和产量形成的影响,为抗臭氧品种的选育提供参考依据。【方法】2013年,利用自然光气体熏蒸平台,以23个水稻品种或株系为供试材料,设置对照(10 n L·L~(-1))和臭氧浓度增高(100 n L·L~(-1))处理,采用组内最小平方和的动态聚类方法,根据供试材料地上部最终生物量对臭氧胁迫的响应从小到大依次分为A类(低度敏感型)、B类(中度敏感型)和C类(高度敏感型)3个类别,分析不同敏感类型水稻株高和分蘖动态、籽粒产量以及产量构成因子对臭氧胁迫的响应及其与成熟期生物量响应的关系。【结果】与对照相比,臭氧胁迫使A、B和C类水稻地上部生物量平均分别下降19%、39%和52%,B和C类达极显著水平。除首期外,臭氧胁迫使其他测定期株高下降,降幅随时间推移逐渐增加,但不同类型水稻的降幅相近。与此不同,臭氧胁迫对分蘖发生的影响因不同水稻类型而异:全生育期平均,臭氧胁迫对A类水稻分蘖数没有影响,但使B类和C类水稻分别下降17%和23%,均达极显著水平。臭氧胁迫使水稻籽粒产量及产量构成因子均显著或极显著下降,其中单位面积穗数(A类水稻没有响应,B和C两类水稻分别下降16%和26%)、每穗颖花数(A、B和C类水稻分别下降16%、19%和27%)和单位面积颖花数(A、B和C类水稻分别下降11%、31%和46%)的降幅在不同类型水稻间差异明显,但在饱粒重、饱粒率和最终产量方面,3类水稻的降幅差异较小。臭氧胁迫导致的产量损失主要与饱粒率和总库容量大幅下降有关,其次亦与穗数和饱粒重的下降有关。臭氧胁迫下,水稻成熟期地上部生物量的响应与生育中后期分蘖数和最终穗数、每穗颖花数以及单位面积颖花数的响应均呈极显著正相关,但与各期株高、饱粒率、饱粒重和最终产量的相关性均不密切。【结论】100n L·L~(-1)臭氧浓度矮化水稻植株,使分蘖发生和颖花形成,特别是灌浆结实明显受抑,进而使最终产量大幅下降,其中生育中后期分蘖数和最终成穗数、每穗颖花数以及总颖花量的变化与水稻敏感类型关系密切,可作为抗臭氧品种选育的参考依据。

Impact of Ozone Stress on Growth and Yield Formation of Rice Genotypes with Different Ozone Sensitivity

【Objective】 In order to cope with the increasing tropospheric ozone concentration, the responses of the growth and yield formation of rice with different ozone sensitivities were investigated. 【Method】 By using glasshouse-type fumigation chambers, 23 rice cultivars or lines were grown in 2013 at two ozone levels: Low ozone concentration as control (C-O₃, 10 nL·L^-1) and high ozone concentration as elevated O₃ treatment (E-O₃, 100 nL·L^-1) from around a week after transplanting until maturity. Based on the decrease in the above-ground biomass under high ozone concentration, these rice genotypes were clustered into three types by the MinSSw (dynamic clustering method-minimum sum of squares within groups) method, namely A (low sensitivity type rice), B (moderate sensitivity type rice), and C (high sensitivity type rice) in the order of ozone sensitivity from low to high, respectively. The effects of ozone stress on plant height, tillering dynamics, grain yield, and yield components were determined, and relationships between their responses to ozone stress and the ozone-induced changes in the above-ground biomass at maturity stage. 【Result】 Compared to the control, ozone stress decreased the above-ground biomass of three rice types A, B, and C at grain maturity by 19%, 38%, and 52%, respectively, and significant treatment effects were detected in B and C. Ozone stress decreased plant height at all growth stages except the earliest stage, and the reduction in plant height was increased gradually with the plant development, but the magnitudes of decline among different rice types were comparable. On the contrast, the influence of ozone stress on tiller formation varied among different rice types. Averaged over the whole growth period, ozone stress had no significant effect on tiller number of rice type A, but significantly reduced those of B (-17%) and C (-23%). Ozone stress significantly reduced grain yield and yield components, and the different rice types exhibited different reduction in panicle number per unit area (A had no response, but B and C decreased by 16% and 26%, respectively), spikelets per panicle (A, B, and C decreased by 16%, 19%, and 27%, respectively) and spikelets per unit area (A, B, and C decreased by 11%, 31%, and 46%, respectively). However, the ozone-induced reduction in filled grain weight, filled grain percentage, and final grain yield showed small differences among three rice types. The ozone-induced reduction in grain yield was mainly caused by the sharp decline of filled grain percentage and total spikelets, and secondly associated with the decline of panicle number and filled grain weight. There were significant positive correlations between the ozone-induced response in above-ground biomass and the tiller number at middle and late growth stages, final panicle numbers, spikelets per panicle, as well as spikelets per unit area, but no close correlation with plant height, filled grain percentage, filled grain weight, or the final grain yield at each growth stage. 【Conclusion】Ozone fumigation of 100 nL·L^-1 during plant growth shortened rice plant height, inhibited tiller production, spikelet formation, and especially grain filling, which led to a dramatic decline in grain yield. Rice ozone sensitivity was closely associated with the ozone-induced changes in tiller number at middle and late growth stage, final panicle numbers, spikelets per panicle, and spikelets per unit area, which can be used as screening parameters in ozone-tolerant rice breeding.