臭氧胁迫使两优培九倒伏风险增加——FACE研究

Ozone stress increases lodging risk of rice cultivar Liangyoupeijiu:a FACE study

近地层臭氧(O3)浓度升高使作物生长发育受到抑制进而使产量下降,但O3胁迫条件下作物抗倒性状的变化及其可能原因均不清楚。FACE(Free Air gas Concentration Enrichment)试验在很少扰动的自然农田实施,其特有的空间优势为研究这一问题提供了最好的机会。依托全球唯一的稻田臭氧FACE技术平台,以杂交稻两优培九为供试材料,设置大气背景O3浓度和高O3浓度两个水平首次对这一问题进行了实验研究。结果表明:高O3浓度使水稻抽穗期单茎(去除叶鞘)倒5、倒4和倒3节间的平均倒伏指数分别增加25%、16%和14%,使抽穗后35 d对应节间倒伏指数分别增加13%、12%和2%,除抽穗后35 d倒3节间外均达显著或极显著水平;高浓度O3使水稻抽穗期和抽穗后35 d植株倒5、倒4和倒3节间的抗折力和弯曲力矩均下降,前者降幅明显大于后者;高O3浓度对抽穗期和抽穗后35 d倒5、倒4、倒3和倒2和倒1节间的长度和粗度影响较小,但使各节间单位长度鲜重和干重一致下降,以单位长度干重降幅更大;高O3浓度使结实期倒5、倒4、倒3、倒2和倒1节间可溶性糖和淀粉含有率均下降,抽穗后35 d降幅大于抽穗期。以上数据表明,未来高浓度臭氧环境条件下两优培九结实期的倒伏风险明显增加,这主要与基部节间抗折能力明显削弱有关,而后者可能又与节间充实程度下降有关。

Lodging is the common problem in rice production,which causes great losses in both yield and grain quality.Rising tropospheric ozone concentration is currently one of the most important air pollutant which suppress plant growth and thus result in yield loss of crops.However little is known about effects of elevated ozone concentration（） on the lodging of rice and related mechanisms.Free Air gas Concentration Enrichment（FACE） system was designed to conduct gas fumigation experiments in natural fields,and spatial advantages of this technology offer the best chance for studying ozone impacts on rice lodging.In this report,a FACE experiment was conducted in a paddy field（119°42′0″E,32°35′5″N） by using an unique FACE system in the world.A two-line hybrid rice cultivar Liangyoupeijiu was grown at ambient（A-O3） or elevated （E-O3）.The effects of elevated on lodging-related traits of rice at heading or 35 days after heading（DAH） were investigated,including lodging index,bending moment,breaking-resistant strength,culm diameter,the fresh and dry weight per unit internode length,the concentration of soluble carbohydrates and starch of different internodes（without leaf sheath）.Compared to the control,exposure to elevated increased lodging index of the fifth,forth and third internodes from the top at heading by 25%,16% and 14% respectively,at 35 days after heading（DAH） by 13%,12% and 2% respectively.The bending moment as well as breaking-resistant strength of the fifth,forth and third internodes from the top were decreased by elevated at heading and 35 DAH,but the decreases in breaking-resistant strength due to ozone stress were larger than in bending moment.Elevated had negligible effects on internode length or culm diameter of the fifth,forth,third,second and first internodes from the top at heading and 35 DAH.However,the fresh weight and dry weight per unit length of the same internodes at heading and 35 DAH were reduced significantly by elevated ,the reduction in dry weight per unit length of each internode was more significant compared with that of fresh dry weight.Elevated decreased concentrations of soluble sugar and starch of all investigated internodes at heading and 35 DAH,and the decrease was more pronounced at late grain-filling stage.The above results indicate that lodging risk of Liangyoupeijiu will increase under future high ozone conditions.The decrease in lodging resistance of rice under ozone stress was associated with weakened basal internodes,which was revealed by significant decrease of breaking-resistance strength of these internodes under elevated .The latter was probably due to poor filling of basal internodes as showed by lower dry weight per unit internode length and reduced concentration of carbonhydrates.