【作者】 戢林；

【导师】 李廷轩； 郑子成；

【作者基本信息】 四川农业大学 ， 植物资源的保护与利用， 2013， 博士

【摘要】 面临人口问题和粮食安全的挑战,如何实现养分资源的高效利用及作物的高产、优质且环境友好已成为当今农业发展的重要研究课题。但实际工作中,两者之间的矛盾却未能得到很好的协调,因此选育养分高效吸收利用的作物品种,从基因型的角度进行品种改良是提高作物养分利用效率的主要研究方向。本研究以目前我国种植规模最大的水稻以及肥料投入量最大的氮素为出发点,从296个水稻品种(Oryza sativa)中选取在产量和氮素利用效率等方面具有显著基因型差异的26个品种为试验材料,通过上培、水培和大田试验,系统研究了高效基因型对氮素的吸收、积累、分配和转运特性,从而为揭示该类型水稻对氮素高效利用的机理,提出协同提高水稻产量和氮素利用效率可行的调控措施提供科学依据。主要结果如下：(1)以产量、氮素籽粒生产效率、氮素收获指数为评价指标,通过聚类分析,将26个水稻品种划分3个类型：高效基因型(美国谷、IR31892-100-3-3-3、IRIT216等品种),中间类型(IR25692、B5996-MR-B-1-5等品种),低效基因型(加早935、IR32429等品种)。其中高效基因型产量、氮素籽粒生产效率和氮素收获指数较低效基因型分别高20.90%、14.96%和6.23%,差异显著。在拔节期和抽穗期,干物质量、氮积累量与籽粒产量和氮素利用效率均呈显著或极显著正相关,表明,抽穗前的物质积累和氮的吸收显著影响水稻产量和氮素利用效率的提高。(2)在正常施氮水平下(200mg kg-1),高效和低效基因型水稻干物质量和氮素积累量差异显著。高效基因型干物质量积累高峰期出现在抽穗—成熟阶段,而低效基因型出现在分蘖—拔节阶段,其中高效基因型干物质量在分蘖—拔节、拔节—抽穗、抽穗—成熟阶段分别是低效基因型的1.12、1.49和5.85倍。高效基因型在分蘖期(移栽后32d)进入氮素高速积累时期,并在48d时积累速率达到最高(美国谷、IR31892-100-3-3-3和IRIT216分别为11.32、12.36和15.83mg d-1plant-1),且持续时间长达49d；而低效基因型也是在分蘖期进入氮素高积累时期,并在37d时积累速率达到最高(加早935和1R32429分别为9.31和7.25mg d-1plant-1),但维持高积累速率的时间较高效基因型短12d。抽穗—成熟阶段水稻干物质量和氮素积累量对产量的影响程度最大,分别为62.65%和47.42%;对氮素籽粒生产效率影响程度分别为14.51%和8.77%,对氮素收获指数影响程度分别为22.14%和15.90%。表明,抽穗至成熟阶段水稻干物质积累和氮素的积累与产量和氮素利用效率的提高关系密切。(3)就根系形态和活力来看,高效基因型在低氮水平下(20mg L-1)的品种优势更为突出,表现为：细分枝根根长在苗期、分蘖期、拔节期和抽穗期分别比低效基因型高32.09%、14.66%、14.40%和12.69%；粗分枝根表面积在拔节期和抽穗期分别比低效基因型高94.70%和64.38%,体积分别高90.24%和58.18%；不定根的根长、表面积和体积在拔节期比低效基因型高40.84%、44.90%和51.02%；根系总吸收面积、活跃吸收面积、氧化力、还原力在拔节后分别为低效基因型的1.3～2.1倍、1.1～3.2倍、1.0～3.0倍、1.4～2.2倍。其中,根系形态指标中以粗分枝根的根长、表面积和体积对氮素积累量的影响程度最大,达47.1%～78.4%。表明,粗分枝根的发育情况可直接影响氮素的吸收,进而对水稻产量的形成和氮素利用效率的提高产生重要影响。(4)高效基因型根系分泌的有机酸以草酸为主,占有机酸总量的80%以上,其次是乙酸和柠檬酸,且有机酸分泌总量在不同供氮水平下均显著低于低效基因型：高效基因型根系分泌的氨基酸以丙氨酸为主,占氨基酸总量的50%以上,其次是丝氨酸、谷氨酸、天冬氨酸、苯丙氨酸、甘氨酸和苏氨酸,且分泌总量在低氮水平下(10和20mg L-1)也显著低于低效基因型。在分蘖期和拔节期,水稻根系分泌有机酸和氨基酸总量与氮素利用效率均呈显著或极显著负相关,其中草酸和天冬氨酸的分泌量与氮素利用效率也呈显著或极显著负相关。表明,有机酸和氨基酸过多的分泌不利于氮素利用效率的提高,减少有机酸(特别是草酸)和氨基酸(特别是天冬氨酸)的分泌,有利于氮素利用效率的提高。(5)对比低效基因型水稻,高效基因型在氮肥用量降低为正常施氮水平(200mgkg1)的50%后,仍能保持较高的产量和氮素利用效率,其氮肥利用率高达50.88%,而低效基因型仅为36.44%。不同施氮水平下,氮在高效基因型不同器官的分配比例为扬花期：叶(38.19%)>茎鞘(35.33%)>根(18.94%)>穗(7.55%),灌浆期：穗(43.51%)>叶(24.80%)>茎鞘(22.38%)>根(9.30%),成熟期：穗(64.90%)>茎鞘(15.15%)>叶(13.85%)>根(6.10%)；且低氮水平(100mg kg-1)更有利于提高氮素在高效基因型穗部的分配量,表现为穗部积累量在扬花期、灌浆期和成熟期分别增加了34.20%、2.51%和0.51%,而低效基因型的穗部积累量在灌浆期和成熟期却降低了23.47%和15.57%。在低氮和正常施氮水平下,高效基因型氮素转运效率分别为60.83%和60.34%,为低效基因型的1.67和1.55倍,且高效基因型氮素转运量表现为叶>茎鞘>根,而低效基因型表现为茎鞘>叶>根。表明,抽穗后叶片较高的转运效率为籽粒的灌浆结实奠定了良好基础。(6)叶绿素相对含量(SPAD值)与叶片氮含量呈极显著正相关,SPAD值的动态变化可反映水稻不同部位叶片氮素的变化情况。在大田试验条件下,高效基因型顶3叶SPAD值在不同施氮水平下均从扬花期开始急剧下降,而顶1叶仅在低氮水平下(60kg hm-2)并在灌浆后期才有所降低。灌浆后期顶1叶SPAD值急剧下降,可表征环境中供氮不足。SPAD值衰减指数可反映水稻花后叶片中氮向穗部转运的状况。在低氮水平下,高效基因型SPAD值衰减指数表现为顶3叶>顶2叶>顶1叶,扬花后25d,不同叶位叶片SPAD值衰减指数达到最高。低氮水平下,高效基因型顶1、2、3叶共有40%-60%的氮素转移到了穗部,因而该水平下产量、氮素籽粒生产效率和氮肥农学效率分别为低效基因型的1.43、1.07和1.46倍,氮肥利用率也达到45.99%。更多还原

【Abstract】 With the increase of population and the decrease of arable land, it has been an important way to increase crop yields and use of limited resources efficiently for the sustainable development of agriculture in China. Nitrogen plays important roles in promoting plant growth and development. Thus, selecting and breeding genotypes with high nitrogen utilization efficiency have become the main research directions to improve nitrogen utilization efficiency in rice. But in practical production, the contradiction between rice yield and nitrogen utilization was not well coordinated, and the mechanism of nitrogen absorption and utilization was even not clear. In this paper, the pot, field and hydroponics experiments were carried out on the farm of Sichuan Agricultural University, Sichuan province, China in2007to2012, by using rice genotype with high nitrogen utilization efficiency as the experimental materials, rice genotype with low nitrogen utilization efficiency as the contrast materials, which selected from296rice cultivars (Oryza sativa). The purpose of this article was to ascertain the mechanism of nitrogen efficient utilization through the analysis of nitrogen absorption, accumulation, distribution and translocation characteristics, besides propose possible control measures to synergistically improve rice yield and nitrogen utilization efficiency. The main results were as follows:(1) Rice genotype with high and low nitrogen utilization efficiency was obtained through hierarchical cluster analysis by using yield, nitrogen grain production efficiency and nitrogen harvest index as evaluation indexes. Rice genotype with high nitrogen utilization efficiency (high NUE) contains11cultivars, including Meiguogu, IR31892-100-3-3-3, IRIT216, while rice genotype with low nitrogen utilization efficiency (low NUE) contains8cultivars, including Jiazao935, IR32429. Grain yield, nitrogen utilization efficiency and nitrogen harvest index of high NUE were20.90%,14.96%and6.23%higher than those of low NUE respectively. Dry matter weight, nitrogen accumulation were significantly or extremely significantly positive correlation to grain yield, nitrogen utilization efficiency and nitrogen harvest index in jointing stage and heading stage. Therefore, matter accumulation and nitrogen absorption significantly affect rice yield and nitrogen use efficiency before heading, especially in the jointing stage and heading stage.(2) Dry matter weight and nitrogen accumulation of high NUE were significantly higher than those of low NUE in each growth stage. The peak of dry matter weight and nitrogen accumulation of high NUE appeared in heading to mature stage, and jointing to heading stage respectively, while The peak of Low NUE only appeared in tillering to jointing stage. Nitrogen accumulation rate of high NUE growth faster in the early stage, and achieved maximum in30～50d after transplanting, then slow down. Nitrogen maximum accumulation rate of Meigugu, IR31892-100-3-3-3and IRIT216calculated through second derivative method was11.32,12.36and15.83mg d-1plant-1, which was935,1.22,1.33and1.70times higher than Jiazao935,1.56,1.70and2.18times higher than IR32429of low NUE respectively. High NUE can maintain higher rate of nitrogen accumulation average duration of49days from tillering stage to heading stage, but low NUE was12days shorter than that of high NUE. Dry matter weight and nitrogen accumulation seriously affected rice yield in heading to mature stage, and the degree were62.65%,47.42%respectively. Degree of influence on nitrogen grain production efficiency were14.51%,8.77%, while degree of influence on nitrogen harvest index were22.14%,15.90%respectively.(3) Under the low nitrogen treatment, there has be significant difference in different types of root morphological characteristics between high NUE and low NUE. Fine lateral root length of high NUE is32.09%,14.66%,14.40%and12.69%higher than low NUE at seeding, tillering, jointing and heading stage, respectively. Coarse lateral root surface area of high NUE is94.70%and64.38%higher than low NUE at jointing and heading stage, while root volume is90.24%and58.18%higher. Adventitious root length, surface area and volume of high NUE is40.84%,44.90%and51.02%higher than those of low NUE at jointing stage. Root total absorbing surface area, active absorbing surface area and reducing capacity of high NUE are decreased significantly with the nitrogen treatment increase at different growth stages. Under the same nitrogen treatment, root total absorbing surface area, active absorbing surface area, oxidation ability and reducing capacity of high NUE are1.3～2.1times,1.1～3.2times,1.0～3.0times and1.4～2.2times higher than those of low NUE. Under the low nitrogen treatment, length, surface area and volume of coarse lateral root have the greatest influence on nitrogen accumulation, the influence degree is47.1%～78.4%.(4) As the main kind of organic acids of the high NUE, the secretion volume of oxalate acid accounts for more than80%of the total organic acid, and those of acetic acid and citric acid are followed. Under the same nitrogen level, the total organic acid secretion of the high NUE is significantly lower than that of the low NUE. As the main kinds of amino acid of the high NUE, the secretion volume of alanine accounts for more than50%of the total amino acid, and is followed by serine, glutamic, aspartic, phenylalanine, glycine and threonine acids. Total amino acids’ secretion and all components of amino acid secretion are decreased with the nitrogen level decrease. Under the low nitrogen levels of10and20mg L-1, the total amino acids secretion of the high NUE is significantly lower than that of the low NUE. At the tillering and jointing stages, the total organic acid and oxalate acid are significant or very significant negative correlated with the nitrogen utilization efficiency, and amino acid secretion and aspartic acid as the same.(5) High NUE was not sensitive as low NUE to nitrogen fertilizer treatment, for reducing nitrogen fertilizer that high NUE can still maintain high yield and nitrogen utilization efficiency, nitrogen recovery efficiency was especially as high as50.88%of high NUE, while low NUE was only36.44%. Nitrogen accumulation in vegetative organs of root, stem, and leaf of high NUE significantly reduced at the condition of low nitrogen level compared with normal nitrogen level, but increased by34.20%,2.51%and0.51%in panicle of high NUE in flowering, filling and mature stage, while decreased by23.47% and15.57%in panicle of low NUE in flowering, filling and mature stage respectively. Nitrogen accumulation distribution in different organs of high NUE manifested as leaf> stem> root> panicle, panicle> leaf> stem> root, panicle> stem> leaf> root in flowering, filling and mature stage respectively. With the advancement of growth period, nitrogen accumulation distribution ratio in root, stem, leaf were significantly reduced, but that in panicle increased from flowering stage (8.22%) to mature stage (65.79%). Nitrogen transfer amount in different organs of high NUE manifested as leaf> stem> root, while low NUE manifested as stem> leaf> root. Nitrogen transfer efficiency of high NUE were60.83%,60.34%under the condition of low and normal nitrogen level, which was1.67and1.55times higher than that of low NUE respectively.(6) Under the condition of field experiment, rice yield of high NUE increased significantly and then decreased with the nitrogen application levels raise, while nitrogen utilization efficiency decreased significantly only. Nitrogen recovery efficiency of high NUE was as high as45.99%, whose yield was42.51%higher than low NUE, nitrogen grain production and nitrogen recovery efficiency was1.07and1.46times higher than low NUE under low nitrogen application level of60kg hm-2. SPAD value of L3(leaf of top3) was starting to fall sharply from flowering stage under different nitrogen levels, but that of L1was starting to fall sharply only after filling stage under low nitrogen levels. Leaf SPAD value of top1fell sharply after filling stage can be characterized for nitrogen deficiency in the environment. SPAD attenuation index in leaves of high NUE manifested as L3> L2> L1under low nitrogen application level, and SPAD attenuation index reached to the highest in the filling stage. SPAD value attenuation index can reflect the nitrogen transshipment from leaves to panicle after flowering under low nitrogen application level.更多还原