【作者】 魏海燕；

【导师】 张洪程； 戴其根；

【作者基本信息】 扬州大学 ， 作物栽培学与耕作学， 2008， 博士

【摘要】 稻田施用氮肥是水稻增产的重要农业措施。但过量氮肥的施用在降低肥料吸收利用效率的同时也带来了一些生态环境的氮污染问题。已有的研究表明,充分挖掘和利用作物自身的氮营养遗传潜力,通过品种的筛选和遗传改良是提高水稻对氮素吸收利用的有效途径。为此,本研究在大田试验条件下,以长江中下游单季稻区有代表性的104份粳稻基因型为研究对象,研究各基因型水稻的产量、氮素利用效率等方面的特点及差异并对其进行评价和分类。随后从长江中下游地区应用较广的迟熟中粳和早熟晚粳两类生育类型中选择氮素利用高效型与低效型的代表性品种,系统研究水稻的物质生产与积累,氮的积累与分配动态,根系形态、生理生化特性,叶片光合特性等生理生态方面的差异,为氮高效品种的遗传改良和水稻生产中的高效氮素管理提供科学依据。主要研究结果如下:1、供试的104份水稻基因型按生育期的长短分为早熟中粳、中熟中粳、迟熟中粳、早熟晚粳和中熟晚粳5种生育类型。在亩施氮素0Kg、10Kg(低氮)、15Kg(中氮)、20Kg(高氮)4种水平条件下,随施氮水平的提高,各基因型水稻的平均籽粒产量呈增加趋势,而基因型间的变异呈减小趋势,变异系数分别从0氮条件下的20.34下降至高氮条件下的16.87。4种氮素水平下,各生育类型水稻的籽粒产量均呈现中熟晚粳>早熟晚粳>迟熟中粳>中熟中粳>早熟中粳的趋势,即随着生育期的推迟,水稻籽粒产量显著提高。早熟中粳、中熟中粳、迟熟中粳、早熟晚粳生育类型中水稻的籽粒产量随着施氮水平的增加而增加,而中熟晚粳生育类型中水稻的籽粒产量呈现中氮>高氮>低氮>0氮趋势。与此同时,相同氮素条件下,同一生育类型中的各水稻基因型产量也存在显著的差异。各基因型水稻的平均氮素利用效率呈现中氮>高氮>低氮的趋势。随氮素水平的提高,基因型间的变异有减小的趋势,变异系数分别从低氮条件下的28.75下降至高氮条件下的21.28。低氮条件下,各生育类型水稻的氮素利用效率呈现中熟晚粳>早熟晚粳>迟熟中粳>中熟中粳>早熟中粳的趋势;中肥条件下呈现早熟晚粳>中熟晚粳>迟熟中粳>中熟中粳>早熟中粳的趋势;而高肥条件下呈现早熟晚粳>迟熟中粳>中熟晚粳>中熟中粳>早熟中粳的趋势。即除中熟晚粳水稻生育类型外,其它生育类型水稻的氮素利用效率有随生育期延长而增加的趋势。相同氮素条件下,同一生育类型中的各水稻基因型氮素利用效率也存在显著的差异。以3种氮肥条件下的最高籽粒产量及其对应的氮素利用效率为指标,对各基因型水稻的产量和氮素利用效率进行综合的评价和分类。可将各生育类型中的不同水稻基因型相应划分出高产高效型、高产中效型、高产低效型、中产高效型、中产中效型、中产低效型、低产高效型、低产中效型和低产低效型9种类型(实际分类结果中由于基因型数量的局限,个别类型有缺失的可能)。依据上述评价和分类方法,可将供试的早熟中粳分为6个类型、中熟中粳分为9个类型、迟熟中粳分为7个类型、早熟晚粳分为8个类型、中熟晚粳分为5个类型。在上述评价和分类基础上,筛选出迟熟中粳中氮高效基因型9优418、武育粳3号、扬粳9538,氮低效基因型农垦57、武农早、郑稻5号;早熟晚粳中氮高效基因型86优8号、武粳15、泗优422,氮低效基因型镇稻196、香粳20-18、T1-56,作为深入揭示氮利用效率差异的研究对象。2、氮素利用高效型和低效型具有代表性的12个水稻基因型的物质生产与积累特性的差异及其与氮利用效率的相关性分析表明,不同氮效率类型水稻群体茎蘖数没有鲜明的特征差异,但氮高效基因型水稻的茎蘖成穗率极显著高于氮低效类型。与氮低效基因型相比,氮高效基因型水稻在有效分蘖临界叶龄期前具有适宜的叶面积、光合势和群体生长速率,物质积累具一定优势,但其占全生育期总积累量的比例较少。有效分蘖临界叶龄至拔节期,氮高效基因型水稻无效分蘖发生少,叶面积指数、光合势、群体生长速率低,物质积累也不具优势。拔节以后,氮高效基因型具有良好的群体质量,叶面积增长较快,群体光合势和生长速率加大,物质积累优势较为明显。3、有效分蘖临界叶龄期((N-n))、抽穗期和成熟期,氮高效基因型水稻的氮素积累量显著高于氮低效基因型,而拔节期差异不明显。除(N-n)至拔节阶段氮高效基因型水稻氮素的阶段性积累量显著低于低效基因型外,其余各阶段均显著高于氮低效基因型。移栽至(N-n)和(N-n)至拔节阶段,氮高效基因型水稻的氮素阶段性积累比例显著低于低效基因型,而拔节至抽穗和抽穗至成熟阶段则表现出相反的趋势。一生中,氮高效基因型水稻抽穗前的氮素转移量和转移率显著大于低效基因型,而其抽穗前氮对籽粒的贡献率却低于氮低效类型。与氮低效基因型相比,氮高效基因型水稻具有在(N-n)前氮素适度积累;(N-n)后至抽穗阶段,氮素的有效积累强而无效积累弱的特点。因此至抽穗期,氮高效基因型水稻的氮素积累量大于低效基因型,且具有较高的氮素转移量和转移率。但由于氮高效基因型水稻在抽穗以后仍具有较强的氮素积累能力,因此其抽穗前氮对籽粒的贡献率相对低于氮低效基因型。4、(N-n)、拔节期、抽穗期和成熟期,氮高效基因型水稻的根干重、根系体积、总吸收表面积、活跃吸收表面积和活跃吸收表面积比均显著大于氮低效基因型稻。(N-n)和拔节期,氮高效基因型水稻的根冠比显著大于低效基因型,而抽穗和成熟期则表现相反趋势。(N-n)、拔节期和抽穗期,氮高效基因型水稻的根系α-NA氧化量显著大于低效基因型;而成熟期,氮高效杂交水稻的根系α-NA氧化量略低于个别氮低效水稻基因。与氮低效基因型相比,氮高效基因型水稻在其一生中具有良好的根系形态和保持较强的根系活力;同时,其生长过程中地下部与地上部的合理比例及协调生长也是促进氮素高效吸收利用的重要原因。5、齐穗后的不同生育时期,氮高效基因型的水稻的叶绿素含量、叶片净光合速率、气孔导度和蒸腾速率均要显著大于低效基因型。齐穗后,氮高效基因型水稻剑叶的光合功能期、叶绿素荧光动力学参数值(Fv/Fm、ΦPSⅡ、qP、qN)均要显著高于氮低效基因型。与氮低效基因型相比,氮高效基因型水稻生育后期具有较好的光合特性,较长的光合功能时期;同时,其PSⅡ反应中心更加稳定,具有更大的光能转化为电化学能的潜力,非光化学猝灭对光合机构也有更好的保护作用。6、齐穗后的不同生育时期,各基因型水稻剑叶的SOD、CAT活性均随叶片的衰老而下降,但氮高效基因型水稻的下降速率要小于低效基因型;剑叶中POD活性随叶片的衰老呈先上升后持续下降,在叶片衰老后期又略有上升趋势;而剑叶中MDA含量随叶片的衰老逐渐增加。齐穗后各时期,氮高效基因型水稻剑叶中的SOD、CAT、POD活性均显著高于低效基因型;而MDA含量要显著低于低效基因型。与氮低效基因型相比,氮高效基因型水稻剑叶后期衰老进程缓慢,叶片的功能期相对较长。更多还原

【Abstract】 N fertilization is yet the most important agricultural method for increasing grain yield while over use of N not only decrease the efficiency of nitrogen absorption and utilization but also causes so many environment problems. Researches have been done revealed that N use efficiency is varied in different rice genotypes. And it is an ideal approach for increasing N use efficiency to explore the potential and screen N efficient rice genotypes. In this research, a field experiment with 104 rice genotypes prevailing in the region of Yangtse rive as materials was carried out to study the characteristics and differences of rice genotypes’grain yield and N use efficiencies. Evaluation and classification of N use efficiencies were also done. Twelve rice genotypes (6 N-efficient and 6 N-low-efficient) belonging to late-maturing medium Japonica and early-maturing late Japonica were selected. The characteristics of rice matter production and accumulation, dynamics of N absorption and utilization, characteristics of root morphology and physiology, different indexes of leaf photosynthesis and etc were studied to provide feasible regulation approaches to increase N use efficiency in rice production. And the main results were as follows.1.Based on the whole growth duration and Dingying’s Standard of classification of rice growth type, 104 rice genotypes in this research were classified into 5 growth types including early-maturing medium Japonica(EMMJ), medium-maturing medium Japonica(MMMJ), late-maturing medium Japonica(LMMJ), early-maturing late Japonica(EMLJ), medium-maturing late Japonica(MMLJ).All rice genotypes were grown under 4 N levels including 0 kg·666.7m-2, 10 kg·666.7m-2 (low), 15 kg·666.7m-2 (medium), 20 kg·666.7m-2 (high). With the increase of N level, the average grain yield of all rice genotypes increased while the differences among rice genotypes decreased with the coefficient of variation dropping to 16.87 at the N level of high from 20.34 at the N level of 0. Rice grain yield increased with the delaying of growth duration under 4 N levels which presented a tendency of MMLJ >EMLJ >LMMJ >MMMJ >EMMJ. With the increase of N level, grain yield of all growth types were increased except for MMLJ which presented a tendency of medium > high >low >0. And the genotypic differences of grain yields belonging to the same growth type were also existed under each N level.The average N use efficiency of all rice genotypes presented a tendency of medium > high >low. With the increase of N level, the differences among rice genotypes decreased with the coefficient of variation dropping to 21.28 at the N level of high from 28.75 at the N level of low. N use efficiency of all growth types increased with the delaying of growth duration under 3 N levels except for MMLJ and it presented a tendency of MMLJ >EMLJ >LMMJ >MMMJ >EMMJ at low N, a tendency of EMLJ > MMLJ >LMMJ >MMMJ >EMMJ at medium N and a tendency of EMLJ > LMMJ > MMLJ >MMMJ >EMMJ at high N. And the genotypic differences of N use efficiencies belonging to the same growth type were also existed under each N level.The maximal yield and its corresponding N use efficiency under 3 N levels were adopted as indexes to estimate and classify rice genotypes. Genotypes of each growth type can be classified into 9 types including high yield and high efficiency type, high yield and medium efficiency type, high yield and low efficiency type, medium yield and high efficiency type, medium yield and medium efficiency type, medium yield and low efficiency type, low yield and high efficiency type, low yield and medium efficiency type and low yield and low efficiency type through the statistical method of cluster analysis. Actually, several types could be absent in practice because of the quantity limit of genotypes. According to the method above, genotypes of EMMJ can be classified into 6 types, MMMJ 9 types, LMMJ 7 types, EMLJ 8 types, MMLJ 5 types. N efficient genotypes including 9 you 418, Wuyujing 3, Yangjing 9538 belonging to LMMJ and 86 you 8, Wujing 15, Siyou 422 belonging to EMLJ together with N inefficient genotypes including Nongken 57, Wunongzao, Zhendao 5 belonging to LMMJ and Zhengdao 196, Xiangjing 20-18, T1-56 belonging to EMLJ were selected for further experiment. 2.12 rice genotypes selected above were adopted as materials to investigate the differences of rice matter production and accumulation. The characteristics of rice matter production and accumulation and their correlations with N use efficiency revealed that, although there was no significant difference in number of tillers per unit ground area between two rice types with different N use efficiencies, the percentage of productive tillers of N efficient genotypes were obviously higher than those of N inefficient genotypes. Compared with N inefficient genotypes, N efficient genotypes had proper leaf area index (LAI), photosynthetic potential (PP), crop growth rate (CGR), and a superior matter accumulation before the critical stage of productive tillering, although their ratios of dry matter to the total accumulation in whole life were relatively low. During the period from the critical stage of productive tillering to heading, the unproductive tillers of N efficient genotypes were fewer than those of N inefficient genotypes. Therefore their LAI, PP, CGR and dry matter accumulation were lower than those of N inefficient genotypes. After the stage of heading, the leaf area, photosynthetic potential of N efficient genotypes increased fast and their crop growth rates accelerated resulting from better population quality. N efficient genotypes presented obvious superiority in dry matter accumulation.3. At the three growth stages including critical stage of productive tillering, heading, and maturing, the amount of N accumulation of N efficient rice genotypes was obviously higher than that of N inefficient genotypes while at the stage of elongating, there was no significant difference in N accumulation between the two rice genotypes. The amount of N accumulation of N efficient genotypes was significantly higher than that of N inefficient genotypes during all growth phases except the phase from critical stage of productive tillering to elongating, at which the amount of N accumulation of N efficient genotypes was significantly lower than that of N inefficient genotypes. The percentage in N accumulation of N efficient genotypes was higher than that of N inefficient genotypes during the growth phases from elongating to heading and from heading to maturing while it showed the reversed trend during the phases from transplanting to critical stage of productive tillering and from the critical stage of productive tillering to elongating. The amount and the efficiency of N translocation before heading were obviously higher in N efficient genotypes than those in N inefficient genotypes. On the contrary, the contribution rate of transferred N to the total N of rice grain at maturity was significantly lower in N efficient genotypes than that in N inefficient genotypes. For N efficient genotypes, the amount of N accumulation before the critical stage of productive tillering was modest. And during the phase from the critical stage of productive tillering to heading, their N accumulation of usefulness were large while the N accumulation of uselessness were few. Therefore, till the stage of rice heading, the amount of N accumulation of N efficient genotypes was obviously higher than that of N inefficient genotypes. And the amount and the efficiency of N translocation before heading of N efficient genotypes were also higher than that of N inefficient genotypes. Because of the strong ability of N accumulation of N efficient genotypes after heading, their contribution rate of transferred N to the total N of rice grain at maturity was relatively lower than that of N inefficient genotypes before heading.4. At four growth stages including the critical stage of productive tillering, elongating, heading, and maturing, the indexes of root morphology and physiology including the root dry weight, root volume, total absorbing surface area of root, active absorbing surface area of root, ratio of active absorbing surface area to total absorbing surface area of N efficient genotypes were obviously higher than those of N inefficient genotypes. At the critical stage of productive tillering and the stage of elongating, the ratios of root to shoot of N efficient genotypes were significantly higher than those of N inefficient genotypes while the trend was contrary at the stages of heading and maturing. Before the stage of maturing, the root oxidation ability ofα-NA of N efficient genotypes were superior to those of N inefficiency genotypes while at the stage of maturing the root oxidation ability ofα-NA of N efficient hybrid rice was appreciably lower than that in some N efficient genotypes. For N efficient genotypes, their root morphology is good and root activity is vigorous which ensures the efficient absorption and utilization of N all their life. Meanwhile the proper ratio of root to shoot and the harmonious growth of root and shoot can also improve the efficiency of N absorption and utilization.5. At five stages after full heading, the photosynthetic indexes of flag leaf including chlorophyll content, net photosynthetic rate, stomata conductance, intercellular carbon dioxide concentration and transpiration rate of N efficient genotypes were obviously higher than those of N inefficient rice type. During the period of grain filling, the photosynthetic function duration and chlorophyll fluorescence parameters of N efficient genotypes were superior to N in efficient genotypes. For N efficient genotypes, they had better characteristic of photosynthesis and longer photosynthetic function duration. Meanwhile steady PSⅡof N efficient genotypes were favorable for effective photochemical quantum yield and strong light protection.6. After the stage of full heading, the enzyme activities of SOD and CAT decreased with the senescence of leaf and the decrease rate of N efficient genotypes were lower than those of N inefficient genotypes. With the senescence of rice leaf, the enzyme activities of POD increased first and then decreased, while it increase appreciably again at the late period of leaf senescence. MDA content of rice leaf increased continuously after the stage of full heading. At five stages after full heading, the enzyme activities of SOD, CAT and POD of N efficient genotypes were significantly higher than those of N inefficient genotypes while the reversed trend was shown in MDA contents of rice leaf. For N efficient genotypes, the process of flag leaf senescence was slow and their leaf photosynthetic function durations were longer than those ofN inefficient genotypes.更多还原