Studies On The Effects Of Potassium Nutrition Level On The Photosynthetic Characteristics And Fruit Quality Of Prunus Persica Var. Nectarina (Ait) Maxim

It's an important tendency of present fruits' development to yield high quality fruits. However,there are lots of quality problems in almost of the nectarine[Prunus persica var. nectarina(Air) Maxim.]fruits produced at present.Photosynthetic reaction is very close related to fruit quality,for the carbohydrates synthesized in it are the material basis of fruit quality's formation.And potassium,a macro-element,is very important for the growth and development of fruit,which takes a very active part not only in enhancing fruiter's photosynthetic properties and the transfer of its photosynthetic outputs,but also in developing fruit qualities.However,at present,the research reports on the aspect are very few.Therefore,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 four-year old 'Yanguang' nectarine,to provide theory direction and the reference of potassium fertilization applying mete.And the following are the research conclusions.1.Potassium nutrition could prompt the formation of nectarine leaves' inner materials. Applying potassium fertilizer could increase the contents of potassium,chlorophyll a, total chlorophyll and the ratio of chlorophyll a to chlorophyll b in the leaves of 'Yanguang' nectarine and its ratio of dry leaf weight to the correspondence leaves area, and prompted light's absorption and passing and photosynthetic outputs' synthesizing and accumulation.2.Potassium nutrition could improve the chlorophyll fluorescence specialty of nectarine leaves.Applying potassium fertilizer with reason could decrease the original fluorescence(Fo) and quenching of non-photoreaction(qN) to reduce the wastage of light,and raise maximal fluorescence(Fm),variable fluorescence(Fv),the ratios of Fv to Fo and of Fv to Fm,Yield and quench of photoreaction(qP) to enhance the potential activity and primary light transformation efficiency of photosystemâ…¡(PSâ…¡),and then raised the yield of light photons and the ability of primary light transformation,and improved the primary reaction characteristics of 'Yanguang ' nectarine. 3.Potassium nutrition could enhance the photosynthetic characteristics of nectarine leaves.With elevating the stomata conductance(Gs) of nectarine leaves,potassium nutrition could prompt their transpiration to adjust temperature of leaf(T1) and heighten water use efficiency(WUE),and simultaneously prompted the absorption and fixation of carbon dioxide(CO₂) in the cells of leaves,and then raised net photosynthetic rate(Pn) and photosynthesis use capacity,and enhanced the assimilation and accumulation of photosynthetic matter in leaves.4.To some extent,potassium nutrition took a part in the light utility of nectarine leaves. Raising the applying quality of potassium fertilizer in reason could increase the photosynthetic use efficiency(PUE) and maximum photosynthetic potential(Pm) of 'Yanguang' and raised the net photosynthetic rate under usual light.Simultaneously,it could enhance the weak light utility of 'Yanguang' nectarine leaves,but slacked strong light utility of them and dwindled the proper scope of light.5.Potassium nutrition could raise nectarine fruit quality significantly.Potassium fertilization could not only improve the fruit inner quality significantly due to raising the contents of soluble solid content,soluble sugar,ratio of sugar to acid,vitamin C and mineral K,but also beautify the fruit appearance through heightening single fruit weight and pigmentation index and the value of L,a and b of fruit tip and fruit body. Additionally,it could decrease fruit cracking rate,increase fruit firmness and lengthen fruit preservation periods under normal temperature(25℃) and low temperature(5℃) separately,so as to elevate the characteristics of resistance to fruit cracking and preservation.6.The primary system of potassium raising the fruit quality of nectarine.Potassium nutrition could elevate the photosynthetic characteristics of 'Yanguang' nectarine and prompt the transformation and accumulation of its leaves' photosynthetic output so as to provide material basis to the growth and development of fruit.Besides that,it was also likely to accelerate the transportation of photosynthetic yield to fruit and the transformation of nutrition materials in fruit.So the fruit quality of 'Yanguang' nectarine was improved.And the potassium fertilizer applying level of NPK₂ was the proper potassium fertilizer applying quality of 'Yanguang' nectarine in the experiments.