【作者】 王岚；

【导师】 黄承和； 常春荣；

【作者基本信息】 海南大学 ， 植物营养学， 2012， 硕士

【摘要】 土壤中供植物吸收利用的氮素主要形态为铵态氮和硝态氮,两种形态的氮源对植株的生理代谢的影响不同。海南岛是我国香蕉重要种植区,不仅氮肥利用率偏低而且香蕉的品质也较低。研究香蕉对铵硝的响应特征旨在了解不同铵硝配比对苗期香蕉生理代谢进程的影响,以期探明适宜巴西香蕉幼苗期生长和吸收的最佳铵硝配比,对进一步了解香蕉氮代谢特点和氮营养特征,进而指导田间合理施肥有着重要的现实意义。为此,本研究以巴西香蕉幼苗(四叶一心)为试验材料,采用营养液培养法研究等氮条件下5种不同铵硝比(NH4+-N/NO3--N：0：100、10：90、25：75、50：50和75：25)对巴西香蕉幼苗生理特性的影响；用改进耗竭法研究等氮条件(100%NO3--N、10%NH4+-N+90%NO3--N、75%NH4+-N+25%NO3--N)、增铵条件(100%NO3--N、10%NH4+-N+100%NO3--N、25%NH4+-N+100%NO3--N)、增硝条件(10%NH4+-N+90%NO3--N、10%NH4+-N+100%NO3--N)香蕉幼苗根系吸收硝态氮的动力学特征。研究的主要结果如下：(1)钱硝配比影响香蕉幼苗生长,并以铵硝配比10：90最适合香蕉的生长。等氮条件下增铵可以提高根系的生长,不同的铵硝配比对地上部分的生长表现不同。香蕉幼苗中氮的含量、累积量以及铵、硝的含量与铵硝配比有关,在全硝的基础上增加铵的比例可以提高氮在地上部分的含量和累积量,促进氮的吸收和利用。铵硝配比影响香蕉叶绿素含量、光合速率以及硝酸还原酶活性,不过光合速率与叶绿素含量没有明显的正相关关系,香蕉体内硝酸盐含量在一定范围内与硝酸还原酶活性正相关。(2)不同铵硝配比条件下香蕉苗期对硝态氮的吸收符合Miehaelis—emen酶动力学模型。数据处理方式中,以Lineweaver-Burke (LB)法得到的数据准确性最高,Vmax用根干重[umol/(g· h), DW]或根鲜重[umol/(g· h)为量纲时得到的动力学参数值均较为合理。(3)香蕉幼苗对N03-的吸收速率随营养液中NO3-浓度的增加而增加,增加幅度随营养液中N03-浓度的增加而减少。NH4+-N存在对香蕉幼苗吸收NO3-有明显抑制作用,加铵不仅显著影响香蕉幼苗硝态氮吸收动力学参数Vmax,对Km的影响也达显著水平。在霍格兰营养液的基础上直接添加10%NH4+-N比将10%NO3--N用NH4+-N替换更能降低香蕉对硝态氮的吸收速率,不过这种处理对对Km的影响不显著。因此,在霍格兰营养液100%硝态氮的基础上,增铵降低了香蕉对硝态氮的吸收速率,增10%NH4+-N降低香蕉对硝态氮的亲和力,增25%NH4+-N对香蕉对硝态氮的亲和力的影响则相反；在本试验条件下,香蕉硝氮吸收系统属于低亲和硝态氮吸收系统。更多还原

【Abstract】 Ammonium and nitrate are the major nitrogen form in soil, and these two kinds of nitrogen source give different effects to plant in physiological level. In Hainan province, as our country important banana planting region, banan has lower yield and quality. This article purpose is to find out the best ratios of NH4+-N/NO3--N for banana seedlings growth and uptakes, and that effects for banana physiology. Thus, nitrogen metabolization and nutrition were illuminated and there was farther realistic significance in guiding field reasonable fertilization.The experiments were carried out by hydroponic culture and modified depletion method, with Brazil banana as the experiment material. These segments were divided into two parts.Project one:effects of NH4+-N/NO3--N ratios on physiological and biochemical characteristics in growth of Brazil banana, banana seedlings were hydroponically grown in nutrient solution, NH4+-N/NO3--N:0:100、10:90、25:75、50:50and75:25, under the equal concentration of nitrogen conditions.Project two:characteristics of nitrate nitrogen uptake, banana seedlings were hydroponically grown under the equal concentration of nitrogen conditions (100%NO3--N、10%NH4+-N+90%NO3--N、75%NH4+-N+25%NO3--N), under the enhanced ammonium nitrogen conditions(100%NO3--N、10%NH4+-N+100%NO3--N,25%NH4+-N+100%NO3--N) and under the enhanced nitrate nitrogen conditions (10%NH4+-N+90%NO3--N、10%NH4+-N+100%NO3--N).The results were showed as follows:(1) Growth of banana seedling was influenced by NH4+-N/NO3--N ratios. When the two ions co-existed, the most suitable ratio was NH4+-N/NO3--N for10:90.Under the equal concentration of nitrogen conditions,increasing the concentration of ammonium nitrogen could promote root growth,while aboveground part growth was different.N content, N accumulation, ammonium and nitrate content were related to NH4+-N/NO3--N ratios.Based on100%NO3--N, N content and N accumulation of aboveground part increased pronouncedly with increasing NH4+-N in nutrient solutions, and the nitrogen uptake and utilization could be increased.Chlorophyll contentsnet, photosynthetic rate and the nitrate reductase activity were influenced by NH4+-N/NO3--N ratios.But there was no significant correlation between photosynthetic rate and leaf chlorophyll content. In a certain range, nitrate content was positive correlation with the nitrate reductase activity. (2) Nitrate absorption of banana seedlings corresponded with the enzymolysis kinetic equation model of Miehaelis—emen. The results indicated that among the different data processing methods, the LB method was the best. When Vmax was expressed as umol/(g h),DW and umol/(g· h),FW, It was more reasonable of the kinetic parameters.(3) NO3-N uptake rate increased with nitrate content in nutrient solution, but the increase rate decreased. NH4+-N in nutrient solution had significant effects on the rate of NO3--N uptake. Both Vmax and Km were significantly influenced by increasing the concentration of ammonium nitrogen.Based on100%NO3---N,10%NH4+-N added directly was more efficient to reduce the rate of NO3--N uptake than10%NH4+-N replacing.But it had no significant directly influence to Km.Therefore, based on100%NO3--N,the rate of NO3--N uptake was reduced by increasing the concentration of ammonium nitrogen;affinity of banana to NO3--N was decreased by increasing10%NH4+-N;but the affinity under increasing25%NH4+-N was opposite.Under the condition of this experiment,system of NO3--N absorption belonged to low-affinity transport system.更多还原