臭氧胁迫对不同敏感型水稻茎秆抗倒性状的影响

为了研究臭氧胁迫对不同敏感类型水稻成熟期茎秆抗倒性状的影响,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,设置室内对照(10 n L·L-1)和臭氧浓度增高(100 n L·L-1)处理,利用组内最小平方和的动态聚类方法,将所有供试材料按地上部成熟期生物量对臭氧胁迫的响应从小到大依次分为A类(-19%)、B类(-39%)和C类(-52%)3个类别。臭氧胁迫环境下A、B和C类水稻倒3节间抗折力降幅差异不显著,均为19%~20%;但倒4节间抗折力分别下降28%、36%和44%,降幅因类型不同而异,与原位测定的植株田间抗折力的变化趋势一致。臭氧胁迫使水稻基部节间的长度、干重、单位长度干重、横截面积、长直径、短直径和茎壁厚均显著或极显著下降,节间干重降幅最大(平均58%),长直径、短直径以及茎壁厚的降幅最小(平均13%~15%);不同节间比较结果显示,臭氧胁迫对这7个参数的影响多表现为第4节间第3节间,其中臭氧处理与节间互作对节间长度、单位长度干重、横截面积、长直径和短直径的影响均达极显著水平;从不同类型看,臭氧胁迫下上述指标的降幅多表现为C类B类A类水稻,其中臭氧处理与水稻类型的互作对节间横截面积、长直径和短直径的影响均达极显著水平。相关分析表明,臭氧胁迫下基部两节间抗折力的响应与对应节间横截面积、长直径、短直径和节间单位长度干重的响应多呈明显的线性正相关。以上结果说明,100n L·L-1臭氧浓度使不同类型水稻茎秆质量明显变劣,臭氧胁迫导致的茎秆抗折力显著下降主要与节间变细相关,其次与节间单位长度干重下降亦有关联。

Impacts of ozone stress on stem lodging resistance of rice genotypes with varying ozone sensitivities

From a week after transplanting until maturity, 23 rice cultivars or lines were grown in glasshouse-type fumigation chambers, with a control group receiving low concentrations of ozone(C-O₃, 10 nL·L^-1) and an elevated O₃ treatment group receiving high concentrations of ozone(E-O₃, 100 nL·L^-1). Based on ozone-induced changes in the aboveground biomass, these rice genotypes were clustered, using the MinSS_w method(a dynamic clustering method using minimum sum of squares within groups) into three types, namely A(-19%), B(-39%), and C(-52%) in ascending order of ozone sensitivity. Ozone stress decreased the breaking resistance of the third internode from the top of rice types A, B, and C by 19% to 20%, but decreased breaking resistance in the fourth internode from the top of the three rice types by 28%, 36%, and 44% respectively. Ozone-induced changes in pushing resistance of the lower part of a single plant showed a trend similar to that of the fourth internode from the top. Ozone stress significantly decreased the length, dry weight, dry weight per unit length, cross-sectional area, maximum stem diameter, minimum stem diameter, and culm wall thickness of the basal internodes, with the dry weight of the internode showing the greatest decrease(on average 58%), whereas the maximum stem diameter, minimum stem diameter, and culm wall thickness showed the least decline(on average 13% to 15%). In most cases, the ozone-induced changes in the seven parameters of the fourth internode from the top were greater than those of the third internode from the top, and ozone-internode interactions were significant for the length, dry weight per unit length, cross-sectional area, maximum stem diameter, and minimum stem diameter of the basal internodes. Among the different rice types, the ozone-induced reduction in each measured parameter followed the pattern C > B > A, and ozone-rice type interactions were significant for the cross-sectional area, maximum stem diameter, and minimum stem diameter of the basal internodes. Correlation analysis showed that the response of basal internode breaking resistance to ozone stress was positively correlated with cross-sectional area, maximum stem diameter, minimum stem diameter, or dry weight per unit length of the corresponding internodes. These results indicated that ozone fumigation at concentrations of 100 nL·L^-1 deteriorated the culm quality of the different types of rice. Ozone stress significantly decreased the breaking resistance of the rice stem, which was mainly associated with basal internode thinning, and also with the decline of dry weight per unit length of the basal internodes.