【作者】 孙园园；

【导师】 马均；

【作者基本信息】 四川农业大学 ， 作物栽培学与耕作学， 2010， 博士

【摘要】 水分和氮素营养是影响水稻生长发育、养分吸收以及产量形成的两个关键因素。目前,节水稻作、提高氮肥利用效率已成为农业生产研究的热点。随着水稻节水管理措施的实施,各种土壤生态环境发生变化,导致土壤硝态氮含量显著增加,进而改变了土壤中铵态氮和硝态氮这两种矿质氮源的比例,可能使硝态氮成为水稻最重要的氮源形态。因此,开展水分胁迫条件及不同形态氮素对水稻生长发育、氮代谢生理、氮素吸收及利用影响的系统性研究具有重要意义。本研究以不同基因型代表性稻种(冈优527、扬稻6号、中旱3号、农垦57)为材料,采用水培、盆钵土培、微区试验,进行不同水分胁迫程度和不同氮素形态的处理,分析了水分胁迫及氮素形态对不同基因型水稻生长发育、氮素吸收及产量形成的影响及其生理机制。主要结果如下：1.种子引发对水分胁迫下不同基因型稻种萌发及幼苗生理特性的影响不同基因型稻种经水引发及聚乙二醇(PEG)渗透胁迫引发处理均能降低稻种丙二醛(MDA)含量,促进可溶性总糖的降解,加快稻种内部糖代谢进程,提高稻种内部相溶性溶质脯氨酸(Pro)及可溶性蛋白质(SP)含量,也有利于提高苯丙氨酸解氨酶(PAL)、超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性,引发效果较为明显。且适度的PEG引发稻种的效果明显好于水引发处理,杂交籼稻在PEG浓度为20%的条件下引发效果最优,而常规粳型水稻在PEG浓度为10%-15%的引发条件下效果较好,但超出最高PEG引发浓度的阀值,会对稻种产生迫害,影响其正常萌发。引发处理后的稻种对不同程度水分胁迫程度的响应表明,适当强度的引发处理后,在水分胁迫下利于激发稻种物质代谢、利于各水稻品种的萌发、幼苗形态指标及保护性酶等生理指标相对于其他水分胁迫均有显著提高,而严重的水分胁迫环境下均不利于稻种的萌发；表明了引发处理虽能提高水分胁迫条件下种子活力,但稻种激发自身对外界萌发环境的协调能力也是有限的,且不同品种间也存在明显差异,籼稻优于粳稻。2.水分胁迫对水稻苗期生长的影响适度水分胁迫(PEG≤5%、水势≥-0.05 MPa)不影响氨基酸态氮(AA-N)、可溶性蛋白含量以及硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合酶(GOGAT)、和谷氨酸脱氢酶(GDH)、谷氨酸草酰乙酸转氨酶(GOT)及谷氨酸丙酮酸转氨酶(GPT)活性；但对硝态氮的吸收和积累有一定刺激作用,并显著降低幼苗净光合速率和干物质累积。相关分析表明,净光合速率的降低对茎叶干物质累积的影响明显大于水稻体内通过代谢抵御外界不良环境的正效应,导致茎叶干物质积累降低。当高水分胁迫强度(PEG≥10%、水势≤-0.15 MPa),不同氮素形态的含量、氮代谢关键酶以及净光合速率显著降低；而且根器官对水分胁迫的敏感程度明显大于叶片。表明水稻幼苗中不同氮素形态的含量、氮代谢关键酶以及净光合速率与水分胁迫强度密切相关；同时也表明了水分胁迫通过对一些氮代谢关键酶--NR、GS、GOGAT、GDH、GOT和GPT活性的影响进而影响氮代谢过程,且氮代谢关键酶活性的强弱与幼苗体内不同形态的氮含量、吸氮量、干物质累积及根系活力等均存在显著相关性。3.适度水分胁迫下增硝营养对不同基因型水稻苗期生长及生理特性的影响正常水分供应条件下,适当的提高硝态氮肥的比例(铵硝配比为50：50),不影响各营养器官中AA-N、可溶性蛋白含量、净光合速率、氮素吸收以及NR、GS、GOGAT、和GDH、GOT及GPT活性,并能促进水稻叶及根中硝态氮含量增加,但硝态氮肥比例>50%,会导致各生理及代谢指标的显著降低,均不利于不同基因型水稻的生长；而适度的水分胁迫下,适当增加硝态氮比例(铵硝配比为50：50)相对于非水分胁迫、纯铵态氮肥处理,更有利于提高功能叶净光合速率、各种氮代谢酶活性,促进渗透调节物质和氮素的积累,能发挥以水促肥的优势,进而促进水稻的生长。此外,不同基因型水稻生长在适度水分胁迫下对增硝营养的响应程度差异显著,籼稻与粳稻相比,杂交籼稻和常规籼稻相比,常规粳型早稻与常规粳型水稻相比,前者在对硝态氮的吸收、各种氮代谢酶活性、净光合速率、氮素吸收利用上均表现出更为明显的优势,同品种耐旱性规律一致。4.不同形态氮肥下结实期水分胁迫对水稻生理特性及产量的影响结实期适度土壤水势(Ψsoil=-25 kPa)处理下,铵硝配比50：50处理较纯铵态氮处理产量增加显著,适当增加硝态氮比例可缓解土壤水分不足所造成的对产量的不利影响。各铵硝配比处理下,穗长、一、二次枝梗数及着粒密度随水分胁迫程度的增加均呈先增后降的趋势,且在-25 kPa土水势时最大,二次枝梗数的下降受土壤水势影响最大,因此,适度的水分胁迫下,在确保增加穗长和保持适宜一次枝梗数的基础上,结合适宜的铵硝配比50：50,可增加二次枝梗数,提高高效叶面积率及着粒密度,提高增产潜能。此外,在土壤水势0 kPa--25 kPa适当增加硝态氮肥比例,有利于促进结实期茎鞘物质转运、提高净光合速率、伤流强度、抗衰老酶活性,还有利于促进稻株氮累积量的提高,但与纯铵态氮处理间未达到显著水平,与纯硝态氮处理间均达到显著水平,而Ψsoil≤-50 kPa增硝的优势减弱,相反增加铵态氮肥的比例(本试验铵硝配比100：0处理)更有利于缓解剑叶净光合速率、抗衰老酶活性的显著降低。5.不同基因型水稻对氮素形态及结实期适度水分胁迫的反应各处理因子对产量及产量构成的影响因素中,不同基因型对其影响最强,氮素形态次之,结实期土壤水势最小。两因素互作对其的交互作用中,不同基因型和氮素形态间的交互作用对其影响最大。不同基因型品种、结实期土壤水势和氮素形态三因素交互作用只对产量存在极显著的交互效应。适度的水分胁迫(Ψsoil=-25 kPa)和适当的增加硝态氮肥比例(铵硝配比为50：50),均有利于不同基因型水稻对铵态氮肥及硝态氮肥的协同吸收与利用,缓解由于水分胁迫所造成的不利影响,能显著促进产量的提高；但也不能过多的提高硝态氮肥的比例,其结果可能抑制水稻对铵态氮肥的吸收,加重水分和氮肥的双重胁迫,导致减产。不同水氮处理下,各品种产量表现为杂交籼稻>常规籼稻,常规粳型水稻>常规粳型早稻(分蘖能力差,有效穗较少)。此外,不同基因型水稻生长在适度土壤水势胁迫下对不同形态氮肥的响应程度差异显著,铵硝配比≥50%处理下,籼稻与粳稻相比,杂交籼稻和常规籼稻相比,常规粳型旱稻与常规粳型水稻,前者在收获指数、氮吸收及利用效率、各种氮代谢酶活性、净光合速率、茎鞘贮藏同化物的运转及提高抗衰老酶活性等方面上均表现出一定的优势,但在适度土壤水势胁迫下,铵硝配比<50%的处理,杂交籼稻和常规粳型旱稻为抵御外界不良生长环境,其体内在对各氮代谢酶及抗衰老酶活性的调控能力上较其他品种更具有优势。更多还原

【Abstract】 Influences of water and nitrogen nutrition are the principal factors on growth and development, nutrient absorption, yield formation in rice. At present, water-saving rice cultivation, improve nitrogen fertilizer using efficiency have become two hot topics of agricultural production research. With implementation of management measures on water-saving cultivation of rice, may lead to changes in soil ecological environment. Subsequently, soil nitrate nitrogen increases significantly and becomes the most important nitrogen source. Therefore, the systematic research concerning the influence of water stress and nitrogen forms on rice physiological growth, nitrogen metabolism, nitrogen absorption and utilization have important significance. In this paper, different rice genotypic varieties including Gangyou 527, Yangdao 6, Zhonghan 3 and Nongken 57 were used as materials under different water stress and nitrogen forms conditions, and water culture, pot and micro-plot field experiments were conducted. Effects of water stress and nitrogen forms on the grain yield, nitrogen metabolism, nitrogen absorption and utilization, and their physiological mechanism were investigated. The main results are as follows:1. Effects of hydropriming and polyethylene glycol (PEG) priming on germination and seedling growth of different genotypic rice under water stressThe results showed that significant higher levels of proline and soluble protein (SP) and lower levels of total soluble sugars and the content of malonicdialdehyde (MDA) in primed seeds were observed as compared with control (nonprimed seeds). Priming accelerated the process of glucose metabolism, improved the activities of phenylalanine ammonia lyase (PAL), superoxide (SOD), catalase (CAT) and peroxidase (POD) in stressed different genotypic rice seeds, moreover, priming effects was relatively significant. Rice seeds could be initiated significantly better by the priming of proper PEG concentration than hydropriming. The results showed that the best reaction conditions was 20%PEG content of hybrid indica rice seeds, but the best reaction conditions was 10%-15%PEG content of conventional japonica rice seeds. It can be damaged by permeability stress and inhibited normal germination of rice seeds if it beyond the threshold value of PEG content, respective. Response of hydroprimed seeds or PEG primed seeds on seedlings growth of different genotypic rice under different water stress. The results showed that, water stress could excite material metabolism, make against rice seeds germination, beneficial to significantly increase kinds of physiological index of seedlings in different genotypic rice, such as morphological index and protective enzymes after the treatment of proper PEG content. But it went against and inhibited germination in serious water stress treatment of rice seedlings. It showed that although seed priming treatment can improve activity of rice seedlings, but the coordination ability of the reaction external germinating environment excited by self-regulation were limited. It also indicated that indica rice had greater PEG tolerance than conventional japonica rice, but better priming effects were observed in hybrid indica rice.2. Effects of water stress on seedling growth of rice and its physiological basisWater stress was caused by adding PEG-6000 into the solution. Slight water stress (PEG≤5%, Water potential≥-0.05 MPa) has little effects on contents of amino acid nitrogen, soluble protein and activities of nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate dehydrogenase(GDH), glutamic-oxalacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT), and moreover the absorption and accumulation of nitrate nitrogen are stimulated. However, photosynthetic rate and dry matter accumulation are significantly inhibited. The dry matter accumulation change is significantly correlated with the regulation of photosynthetic rate more than that positive effect of resisting badness effect from environment. Therefore, photosynthetic rate has much more effect on dry matter accumulation than metabolism in vivo of rice. When PEG concentration≥10%(Water Potential≤-0.15 MPa), the concentrations of different nitrogen forms, some key enzymes of nitrogen metabolism and photosynthetic rate are significantly decreased. These effects on roots under the water stress are significantly larger than those on leaves. The above results indicate concentrations of different nitrogen forms and some key enzymes of nitrogen metabolism and photosynthetic rate are closely related to the intensity of water stress. 3. Effect of partial replacement of ammonium by nitrate on some physiological characteristics by genotypes of rice at the seedlings stage under moderate water stressUnder normal water condition, moderate reduce the ratio of ammonium/nitrate nitrogen (ammonium/nitrate ratio is 50:50), had little effects on contents of amino acid nitrogen (AA-N), soluble protein, photosynthetic rate, nitrogen uptake, and activities of NR, GS, GOGAT, GDH, GOT and GPT, and could promoted nitrate nitrogen content in leaves and roots. But if nitrate nitrogen content> 50%, it could significantly decreased physiological and metabolism indexes and inhibited the growth of different genotypic rice seedlings. It was more beneficial to improve photosynthetic rate of function leaves, improved the activities of nitrogen metabolism key enzymes, promoted accumulation of osmotic adjustment materials and nitrogen uptake, could full play advantage of promoting fertilizer by proper water stress and promoted the growth in rice of moderate reduce the ammonium/nitrate ratio is 50:50 than 100:0 and normal water condition. In addition, the response extent of different genotypic rice was significant differences under proper water stress. Compared with indica rice and japonica, hybrid indica rice and conventional indica rice, conventional japonica upland rice and conventional japonica rice, the former is much obviously better than the latter of nitrate absorption, the activities of nitrogen metabolism key enzymes, photosynthetic rate, nitrogen absorption and utilization was consistent with drought tolerance of different genotypic rice.4. Effect of status of soil moisture on the physiological characteristics and yield components under different nitrogen forms during grain filling in riceProper soil moisture (Ψsoil=-25 kPa) during grain filling and ammonium/nitrate ratio 50:50, yield significantly increased than ammonium/nitrate ratio 100:0, and could alleviate adverse effects of yield in short of water. Kinds of ammonium/nitrate ratio treatment, panicle length, primary branch number, secondary branch number and spikelet density were all first and then decreased during water stress increased, and the biggest was-25 kPa soil moisture treatment. Effects most influential of secondary branch number on soil moisture. Therefore, proper soil moisture could make sure improve panicle length and keeping suitable primary branch number, combined with suitable ammonium/nitrate ratio 50:50 could increase secondary branch number, efficient leaf area ratio and spikelet density, improve the potentiality of increase yield. Furthermore, soil moisture 0 kPa--25 kPa and proper significantly increased with ammonium/nitrate ratio, benefit to promote redistribution of reserves in stem and sheath, photosynthetic rate, bleeding intensity, anti-aging enzymes activities and nitrogen cumulate during grain filling in rice. But there were not reached significant level compared with ammonium nitrogen and significant level compared with nitrate nitrogen. But when soil moisture (Ψsoil≤-50 kPa), advantage decreased ammonium nitrogen ratio (ammonium/nitrate ratio is 100:0), is more beneficial to relief significantly decreased photosynthetic rate and anti-aging enzymes activities.5. Effect of status of proper soil moisture under different nitrogen forms during grain filling in different genotypic riceEffect treatment factors of yield and yield compositions, influence of different genotypic, nitrogen forms took second place, soil moisture was the least. Two factors toxicity interaction effect, the interaction of different genotypic and nitrogen forms was the biggest one. There was an extremely significantly interaction effect to yield among different genotypic rice, soil moisture and nitrogen forms. Proper soil moisture (Ψsoil≤=-25 kPa) and proper increased nitrate nitrogen ratio (ammonium/nitrate ratio is 50:50), were all beneficial to increase absorb and utilization ammonium and nitrate nitrogen, could relief adverse effect of water stress, significantly promoted increase yield. But could not improve the rate of excessive nitrate nitrogen ratio, because it would inhibited the absorption of ammonium nitrogen, aggravated double stress of water and nitrogen fertilizer, finally lead to yield reduction. Under different water and nitrogen treatments, kinds of rice variety were all manifested as hybrid indica rice> conventional indica rice, conventional japonica rice>conventional japonica upland rice (tillering ability is so poor and effective panicles are less). Furthermore, different nitrogen forms under proper soil moisture in different genotypic rice were significant differences. Under ammonium nitrogen ratio≥50%, compared with indica rice and japonica, hybrid indica rice and conventional indica rice, conventional japonica upland rice and conventional japonica rice, the former is much obviously better than the latter of harvest index, nitrogen absorption and utilization, the activities of nitrogen metabolism key enzymes, photosynthetic rate, material transport in stem-sheath and improve anti-aging enzymes activities. But under proper soil moisture and ammonium nitrogen ratio< 50%, two varieties which have stronger drought tolerance: hybrid indica rice and conventional japonica upland rice have more advantages of the activities of nitrogen metabolism key enzymes and anti-aging enzymes than other rice varieties.更多还原