【作者】 许高平；

【导师】 黄建晔； 杨连新；

【作者基本信息】 扬州大学 ， 作物栽培学与耕作学， 2011， 硕士

【摘要】 大气CO2浓度已从工业革命前的280μmol·mol-1上升到目前的381μmol mol-1,最新模型预测2050年大气CO2浓度将至少达到550μmol·mol-1,到本世纪末将上升到730～1020μmol mol-1。水稻是最重要的粮食作物之一。根系是水稻吸收水分和养分的主要器官,水稻根系还能合成多种生理活性物质,对水稻产量形成具有举足轻重的影响。大气CO2浓度升高对水稻根系形态性状和生理活性有什么影响?这种影响是否因不同品种而异?与籽粒产量有什么关系?这方面的报道甚少。为了明确这些问题,本试验依托建于江苏省江都市小纪镇良种场试验田内稻田]ACE (Free-Air-CO2-Enrichment)技术平台,以12个水稻品种为供试材料,设计比大气背景CO2浓度高200μmol·mol-1的FACE处理对此进行了研究,以期为未来大气C02浓度升高条件下优化我国水稻生产提供实验依据。主要结果如下：1、不同水稻品种各期单条不定根长度、单条不定根粗和单条不定根体积均存在极显著差异。比大气背景C02浓度高200μmol·mol-1的FACE处理使水稻分蘖期单条不定根干重、单条不定根长度、单条不定根粗和单条不定根体积分别平均增加6%(P>0.1)、1%(P>0.1)、6%(P<0.01)和16%(P<0.05),使抽穗期对应根系性状平均分别增加13%(P<0.01)、8%(P>0.1)、5%(P>0.1)和6%(P<0.01),不同品种对高浓度CO2的响应趋势基本一致。2、不同水稻品种各期每穴、每穴不定根总长、每穴根体积和每穴不定根数均存在极显著差异。大气CO2浓度升高使水稻分蘖期每穴、每穴不定根总长、每穴根体积和每穴不定根数分别平均增加26%、22%、37%和21%,使抽穗期对应根系性状平均分别增加31%、22%、24%和15%,均达极显著水平,不同品种趋势基本一致。高浓度CO2环境下水稻每穴根系的重量、长度和体积明显增加主要是不定根发生的数量增多所致,其次亦与单条不定根的生长受到促进有关,表现在单条不定根的长度、直径和体积增加。3、不同水稻品种间单位根干重的总吸收面积和活跃吸收面积存在极显著差异。大气CO2浓度升高使水稻抽穗期单位根干重的总吸收面积和活跃吸收面积平均分别减少16.4%和16.1%,均达极显著水平。高浓度CO2环境下水稻根系活性下降可能与根系的生长量大以及植株含氮率明显降低有关。4、不同水稻品种间每穴总吸收面积和每穴活跃吸收面积存在极显著差异。大气CO2浓度升高使水稻每穴根重显著增加,但使单位根重活性明显下降,因此对每穴根系活性的影响较小。FACE处理使水稻抽穗期每穴总吸收面积和每穴活跃吸收面积平均分别下降3.0%和2.6%,均未达显著水平。不同品种趋势基本一致。5、大气CO2浓度升高使所有供试品种产量平均增幅达15%,增幅因不同品种而异。相关分析表明,水稻籽粒产量与抽穗期每穴、每穴不定根总长、每穴根体积和单条不定根粗均呈正相关,其中与每穴(r=0.497**,n=72)和单条不定根粗关系比较密切(r=0.430**,n=72)。水稻籽粒产量与抽穗期每穴总吸收面积(r=-0.433”,n=72)和活跃吸收面积呈极显著负相关(r=-0.428**,n=72)。以上结果说明大气CO2浓度升高条件下水稻根系重量和直径显著增加可能是籽粒产量增加的重要原因之一。更多还原

【Abstract】 The concentration of atmospheric CO2has risen from approximately280μmol mol-1in preindustrial times to381μmol·mol-1at present. The latest model predicts that the CO2concentration [CO2] will reach550μmol·mol-1around2050, and by the end of the21st century, it will reach730-1020μmol·mol-1. Rice (Oryza Sativa L) is one of the most important food crops. Root system of rice is a major organ responsible for water and nutrient acquisition, which also synthesizes physiological active compounds, therefore, rice roots have great impact on grain yield formation. To date, only a few number of studies conducted under flooded paddy soils aimed at examining root system response to rising CO2concentration. The following aspects are unclear:Will elevated atmospheric CO2concentration influence morphology characters and biological activities of rice roots? Are there genotypic differences among rice cultivars? What is the relationship between root characters and grain yield? In order to answer these questions, A FACE experiment was carried out in a field located in Jiangdu county, Jiangsu province, using12different rice cultivars as tested cultivars. The CO2concentration in FACE treatment was580μmol·mol-1(200μmol·mol-1above Ambient [CO2]). The main objective of this experiment was to study the effects of elevated CO2 concentration on rice root system and the relationship between root characters and grain yield, and to provide the experimental evidence for improving future rice production under high CO2concentration. Results showed as follows:1. There were significant differences among all tested cultivars (P<0.01) on average length, diameter and volume per adventitious root. Compared to ambient[CO2], the average weight, length, diameter and volume per adventitious root at tillering stage increased by6%(P>0.1),1%(P>0.1),6%(P<0.01) and16%(P<0.05) under FACE, respectively. The average weight, length, diameter and volume per adventitious root at heading stage were enhanced under FACE by13%(P<0.01),8%(P>0.1),5%(P>0.1) and6%(P<0.01), respectively. Similar trends were observed for all cultivars.2There were significant differences among all tested cultivars (P<0.01) on the dry weight, total length, volume and number of adventitious roots per hill. Elevated CO2concentration significantly increased root dry weight, total root length, root volume and number of adventitious roots per hill at tillering stage by26%,22%,37%and21%, respectively. Root dry weight, total root length, root volume and number of adventitious roots per hill at heading stage was enhanced under FACE by31%,22%,24%and15%, respectively. Similar trends were observed for all cultivars. The significant enhancement in root dry weight, root length and root volume of adventitious roots per hill under high CO2concentration were mainly due to higher number of adventitious root, secondly related to better growth of each adventitious root, such as the increment of length, diameter and volume per adventitious root).3There were significant differences among all tested cultivars (P<0.01) on the total absorption area per unit root dry weight, as well as the active absorption area per unit root dry weight. Elevated CO2concentration significantly decreased the total absorption area per unit root dry weight and the active absorption area per unit root dry weight by16.4%and16.1%, respectively. The reduction of rice root activity under high CO2probably related to the greater biomass accumulation and lower plant nitrogen content in rice plant.4There were significant differences among all tested cultivars (P<0.01) on the total absorption area per hill root dry weight, the active absorption area per hill root dry weight. Elevated CO2concentration significantly increased root dry weight per hill, but decreased root activity per unit root dry weight, hence little effect of elevated [CO2] on root activity per hill was observed. FACE treatments significantly decreased the total absorption area per hill root dry weight and the active absorption area per hill root dry weight at heading stage by3.0%and2.6%, respectively. Similar trends were observed for all cultivars.5Elevated CO2concentration increased grain yield of tested cultivars by15%in average, but such increases varied with cultivars. The result of correlation analysis showed that grain yield was positively correlated with root dry weight per hill, total root length per hill, root volume per hill, as well as average diameter per adventitious root. Among all investigated root characters, root dry weight per hill (r=0.497**, n=72) and average diameter per adventitious root (r=0.430**, n=72) showed most close relationship with grain yield. By contrast, negative correlation was found between grain yield and the total absorption area per hill root dry weight (r=-0.433**, n=72) or the active absorption area per hill root dry weight (1=-0.428**, n=72). These results indicated that higher grain yield of rice under FACE might attribute to the significant changes in root weight and root diameter.更多还原