【作者】 马惠民；

【导师】 王波； 陆增根；

【作者基本信息】 苏州大学 ， 农业推广， 2009， 硕士

【摘要】 本论文以青菜为研究对象,采用水培条件,从植物营养和植物生理的角度来探讨不同青菜品种对不同铵硝比反应差异及其机理的影响规律,并筛选出对不同铵硝配比敏感及钝感的青菜品种,然后利用所筛选出的典型品种青菜研究不同形态氮素营养对青菜的光合特性、根系生长发育特性、以及对NPK吸收累积的影响。研究结果表明:1不同铵硝配比对不同品种青菜的生物量（地上部、地下部）有显著的影响,供试4个品种（苏州青、青丰1号、上海青和热优2号）的生物量（地上部、地下部）均随着营养液中NH₄⁺-N比例的增加而增加,并在营养液中铵硝配比为25:75时达最高。然后,随着NH₄⁺-N比例的进一步增加,4个青菜的生物量（地上部、地下部）反而迅速下降,当营养液中铵硝配比为50:50时,其生物量反而低于全硝处理。说明通过改变营养液中铵硝配比可以改变青菜的生长发育,但营养液中过高或过低的NH₄⁺-N比例均要影响青菜的生物量,只有适宜的铵硝配比对青菜生长发育才具有较好地促进作用。本研究认为适合青菜生长的最佳铵硝配比为25:75。不同铵硝配比对青菜根系的根冠比有影响,随着营养液中NH₄⁺-N比例的增加,青菜的根冠比先上升,然后下降。2不同铵硝配比对青菜地上部硝酸盐含量有显著影响,4个品种青菜地上部的硝酸盐含量均是随着营养液中NH₄⁺-N比例的上升而下降。3不同品种青菜对不同铵硝配比的反应不一样。从不同铵硝配比与青菜生物量（地上部、地下部）及青菜地上部硝酸盐含量的响应情况来看,在供试的4个青菜品种中,苏州青（Suzhouqing, Szq）和热优2号（Reyou 2, Ry2）属于典型青菜品种,其中苏州青对不同铵硝配比最为敏感,是敏感型青菜品种,而热优2号对不同铵硝配比敏感程度最低,是钝感型青菜品种。4不同铵硝配比对2个典型品种青菜各部位含氮量的影响不大,但对植株中磷、钾含量的积累有显著影响,研究显示植株体内磷、钾含量以铵硝比为25:75时最高。同时不同铵硝配比对2个典型品种青菜的光合特性有显著的影响。随着营养液中NH₄⁺-N比例的增加,青菜叶片叶绿素含量、净光合速率及气孔导度均随着增加,并在营养液中NH₄⁺-N比例为25%时达最高。然后,随着NH₄⁺-N比例的进一步增加到50%,上述特性反而迅速下降。叶片的胞间二氧化碳浓度随着营养液中NH₄⁺-N比例的增加而下降,并在营养液中NH₄⁺-N比例为25%时达最低。然后,随着NH₄⁺-N比例的进一步增加到50%,叶片的胞间二氧化碳浓度反而有所增加。5从不同铵硝配比对不同品种青菜光合特性影响的角度来看,与热优2号青菜相比,苏州青对环境中不同铵硝配比的变化更为敏感,热优2号对环境中不同形态氮素营养及不同铵硝配比的变化钝感。6不同铵硝配比对青菜的根系特征参数有显著的影响。随着营养液中NH₄⁺-N比例从0%增加到10%及25%,青菜根系表面积、体积、总根长及侧根数量均随之增加,并在营养液中NH₄⁺-N比例为25%时达最高,且在0%处理与25%处理的差异均达到显著或极显著水平。随着营养液中NH₄⁺-N比例的进一步增加到50%,根系表面积、体积、总根长及侧根数量参数反而迅速下降。7从不同铵硝配比对不同品种青菜根系特征参数影响的角度来看,与热优2号青菜相比,苏州青对环境中不同形态氮素营养的变化更为敏感。更多还原

【Abstract】 This dissertation is aimed to clarify the mechanism of NH₄⁺ enhancement on pakchoi growth from the aspects of physiology and biochemistry. Hydroponic experiments were carried out to study the effect of different forms of N on photosynthetic characteristics, root growth and development, uptake of N, P and K, as well as the yield and quality of pakchoi.The results obtained are listed as follows.1. Five cultivars of pakchoi, very popularly cultivated in south-east China, such as Qf 1, Szq, Shq and Ry 2, responded in a significantly different way to different ratios of NH₄⁺-N : NO₃^--N. Biomasses of roots and shoots of these cultivars increased with the increasing of NH₄⁺-N:NO₃^--N ratio, and obtained the greatest value at 25:75 of NH₄⁺-N:NO₃^--N. Therefore, different ratios of NH₄⁺-N:NO₃^--N in nutrient solution could influence the biomass of pakchoi, and the best ratio of NH₄⁺-N:NO₃^--N for pakchoi growth and development is 25 : 75. Different ratio of NH₄⁺-N:NO₃^--N in nutrient solution could affect the ratio of root and shoot, which was increased with the increased application of NH₄⁺-N, and then decreased with the further increasing of applied NH₄⁺-N.2. Different ratios of NH₄⁺-N:NO₃^--N in nutrient solution significantly affected the contents of NO₃^- in shoots of four cultivars. NO₃^- contents of four cultivars decreased with the increasing of the percentage of NH₄⁺-N in total N applied.3. Different cultivar of pakchoi responded differently to different NH₄⁺-N:NO₃^--N ratios in nutrient solution. Szq was a mostly sensitive cultivar and Ry 2 was a mostly insensitive cultivar to different ratios of NH₄⁺-N:NO₃^--N in terms of biomass production and NO₃^- content among the cultivars tested in this experiment.4. There aren’t significant effect of different NH₄⁺-N:NO₃^--N ratios in nutrient solution on nitrogen content of pakchoi. But there are significant effect of different NH₄⁺-N:NO₃^--N ratios in nutrient solution on P and K content of pakchoi. The photosynthetic characteristics of cultivars, Szq and Ry 2, responded in a significantly different way to different ratios of NH₄⁺-N:NO₃^--N. The SPAD readings, net photosynthesis rate （Pn） and stomatol conductance （Cond） of Szq and Ry 2 cultivars increased with the increasing of NH₄⁺-N:NO₃^--N ratio from 0:100 to 25:75, and they were found to be the highest in 25:75 for NH₄⁺-N:NO₃^--N. However, they decreased with the increasing of NH₄⁺-N:NO₃^--N ratio further.5. Results from the photosynthesis experiments showed that the cultivar named as Szq was a more sensitive genotype to different ratios of NH₄⁺-N:NO₃^--N than the cultivar named as Ry 2 in this experiment. Therefore, Szq was a sensitive genotype and Ry 2 was a insensitive genotype to different ratios of NH₄⁺-N:NO₃^--N.6. Different ratios of NH₄⁺-N:NO₃^--N in nutrient solution could greatly affect the root growth of Szq and Ry 2. Total root surface area, root volume, total root length and root number increased with increased application of NH₄⁺-N, percentage from 0% to 25%, They were found to be the highest in 25:75 of NH₄⁺-N:NO₃^--N, and then decreased quickly with the further increase NH₄⁺ amount. This result indicated that moderate NH₄⁺ addition could improve the development of root growth of pakchoi.7. In terms of the effects of different ratios of NH₄⁺-N:NO₃^--N on root architectures of Szq and Ry 2 cultivars, Szq had greater response and be more sensitive than that of Ry 2 under moderate ratio of NH₄⁺-N:NO₃^--N.更多还原