Study On The Effect Of Potassium Nutrition Level On The Photosynthetic Characteristics And Fruit Quality Of Nai-plum(Prunus Salicina Lindl. Var. Cordata J. Y. Zhang Et Al.)

Now, high quality and pollution-free fruit production has become an important trend in the development of fruit It's an important tendency of present fruits'development to yield high quality fruits. Potassium is a functional element, it is essential to plant growth and nutrient elements. In plant, potassium is not only as an activator of enzyme, but also can promote photosynthesis and respiration and pest and adverse environmental resistance.But the influence of Nai-plum fruits quality reports are very less, the experiments primarily explored the system of potassium raising fruit qualities, with studying the effects of four different potassium nutrition levels (NPK₀ or CK,NPK₁,NPK₂ and NPK₃) on the photosynthetic characteristics and fruit quality of ten-year old Nai^plum, for the production of Nai^plum scientific potassium fertilizer application, achieve high quality and efficient cultivation target provide theoretical basis. And the following are the research conclusions.1. potassium could increase leaf area,improve chlorophyll synthesis and CO₂ anabolism.In the experiment, applying potassium fertilizer increased the contents of chlorophyll a and total chlorophyll in Nai-plum leaves and ratio of dry leaf weight to the correspondence leaves area, and boosted light's absorption and passing, and photosynthetic outputs'synth-esizing,transportation and accumulation.2. With elevating the stomata conductance (Gs) of Nai-plum leaves, potassium nutrition enhanced transpiration, boosted the temperature of leaf (Tl) and improved water use efficiency(WUE),and simultaneously prompted the absorption and fixation of carbon dioxide (CO₂) in cells of leaves, and raised net photosynthetic rate (Pn) and photosynthesis use capacity, and that enhanced the assimilation and accumulation of photosynthetic matters in leaves.3. Potassium nutrition took a part in the light utility of Nai-plum leaves. By raising the applying quantity of potassium fertilizer in reason lowered the invalid loss of light,and prompted leaves' photosynthesis function, and made use of the absorbed light for photo- synthesis, enhanced the photosynthetic use efficiency (PUE) and maximum photosynthetic potential of Nai-plum leaves. 4. Applying proper potassium fertilizer improved the chlorophyll fluorescence specialty of Nai-plum leaves,and reduced the original fluorescence (Fo) and quenching of non-photoreaction (qN) to decrease the wastage of light, and enhanced maximal fluorescence (Fm), variable fluorescence (Fv), the ratios of Fv to Fm and the ratios of Fv to Fo, Yield and quench of photoreaction (qP) to enhance the potential activity and primary light transformation efficiency of photosystemâ…¡(PSâ…¡), and enhanced the yield of light photons and the ability of primary light transformation, and improved the primary reaction characteristics of Nai-plum leaves.5. Potassium fertilization not only heightened single fruit weight, pigmentation index, shape index of fruit and the value of L, a and b of fruit pulp, but also prompted the fruit inner quality significantly due to raising the contents of soluble solid content, soluble sugar,vitamin C,mineral K and ratio of sugar to acid. Furthermore, it increased fruit firmness and lengthen fruit preservation periods under normal temperature(25℃)and low temperature (5℃), so as to elevated the characteristics of resistance to fruit preservation.6. The primary system of potassium raising the fruit quality of Nai-plum. Potassium nutrition prompted the photosynthetic characteristics of Nai-plum, and improved the synth esizing, transformation and accumulation of leaves'photosynthetic output, so as to provided material basis to growth and development of Nai-plum fruit. And then it was also likely to quicken the transportation of photosynthetic yield to fruit and the transformation of nutrition materials in fruit. The potassium fertilizer applying the level of NPK₂ was the proper potassium fertilizer applying quality of Nai-plum in the experiments.