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The main topic of spectrophotometry and chlorophyll fluorescence techniques as a means to study exogenous physiological changes poinsettia seedlings naphthaleneacetic acid (NAA) conditions, in order to investigate the effect of NAA poinsettia seedling drought resistance aimed at Poinsettia Drought performance evaluation the drought breeding water-saving cultivation provides scientific theory. Text under poinsettia poinsettia \physiological characteristics of the results are as follows: (1) the varieties of poinsettia seedlings are very sensitive to water deficit, weak drought resistance. (2) with the degree of water stress intensifies, the the poinsettia leaf soluble sugar content, proline content, SOD activity and POD activity increased and then decreased trend; short-term increase in the chlorophyll content, after a sharp decline to a lower level: MDA content along with increased stress, and gradually increase stable late duress; chlorophyll fluorescence parameters Fo and qN increased significantly, Fm, Fv / Fm, Fv / Fo, Yield and qP decreased significantly. Under mild stress, adaptation and ability to regulate Poinsettia osmoregulation substances and protective enzymes coordinated, timely removal of excess reactive oxygen species, maintenance of membrane stability, better able to adapt to the arid environment; severe stress. serious damage to the balance between the generation of reactive oxygen species and clear cell osmotic adjustment weakened membrane permeability increases, at the expense of the PS II reaction center, and inhibition of photosynthesis, electron transport and photosynthetic primary reaction process, so that photosynthetic reduced efficiency and eventually leading to seedling death (3) under water stress, the the NAA solution of the Poinsettia various biochemical and physiological changes have a significant impact. Concentration of 0.05-0.5mg · L-1 NAA treatment can inhibit elevated soluble sugar and MDA Pro content and enzyme activity remained relatively stable, and reduce the decomposition of chlorophyll; addition, can also slow the rise of Fo and qN inhibit Fm, Fv / Fm, Fv / Fo, Yield and qP decreased to maintain a relatively stable level of chlorophyll fluorescence; concentration of 1.0mg · L-1 NAA treatment effect contrast. Description low concentrations of NAA to enhance the efficiency of the active oxygen scavenging system to ease the water shortage in damage to the membrane system and PS II reaction center, improve poinsettia seedling drought resistance, and promote plant growth. High concentrations of NAA treatment may aggravate the water stress injuries, reduce poinsettia seedling drought resistance, and to accelerate the death of plants wilting. (4) In this study, low concentrations of processing to 0.5mmg · L-1 NAA effect.
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