Effects Of Fertilization On Flower Bud Differentiation And Physiological-biochemical Characteristics Of Camellia Oleifera

In order to comprehend the influence mechanism of N,P,K on flower bud differenti ation,photosynthesis,antioxidant enzyme activity and fertilizer requirement pattern and pr ovide the theoretical basis for the efficient cultivation and sustainable development of C-amellia oleifera,the excellent clone ‘Chang Lin 4#’ of Camellia oleifera was chosen as research object,and the orthogonal experimental design with 3 factors and 3 levels was adopted.The test factors were N,P and K:Urea（Available nitrogen content 46.4 %）,Calci um magnesium phosphate fertilizer（P₂O₅ content 12.0 %）,Potassium sulphate（K₂O conten t 51.0 %）.The research set a blank control group（CK）,and 10 experimental treatments were conducted.The effects of different N,P,K fertilization ratio on flower bud differenti ation,photosynthetic physiology and antioxidant enzyme activity were studied,and the res earch drew the following conclusions:（1）According to the morphological changes of ‘Chang Lin 4#’ Camellia oleifera flower bud,it was divided into 6 periods:Predifferentiation stage（Early June to Mid-june）;Sepal formation stage（Mid-june to Late June）;Petal formation stage（Late June to Early July）;Pistil and stamen formation stage（Early July to Late July）;Ovary and anther formation stage（Late July to Early August）;Pistil and stamen mature stage（Early August to Mid-september）.（2）In the test fertilization level,the application of appropriate amount of N,P and K fertilizer was beneficial to the flower bud differentiation of Camellia oleifera.In the predifferentiation stage,N fertilizer significantly promoted the elongation of Camellia oleifera mixed buds;In the sepal formation stage,N fertilizer significantly promoted the elongation of flower bud,and K fertilizer significantly promoted the increase of flower bud width.In the petal formation stage and the pistil and stamen formation stage,P fertilizer significantly promoted the elongation of flower bud.In the ovary and anther formation stage,N fertilizer significantly promoted the elongation of flower bud.In the pistil and stamen mature stage,K fertilizer significantly promoted the increase of flower bud width.（3）In the process of Camellia oleifera flower bud differentiation,the application of N,P and K fertilizer significantly influenced the level of endogenous hormone content.In the predifferentiation stage,the content of ZR and IAA were significantly increased by N and P fertilizer,and N,P and K fertilizer significantly increased the ABA content.In the sepal formation stage,N,P and K fertilizer significantly reduced the ZR content of flower bud;N,K fertilizer significantly reduced the ABA content;N,K fertilizer significantly increased the IAA content;K fertilizer significantly reduced the GA₃ content.In the petal formation stage,the content of ZR was significantly increased by N and K fertilizer;N,P and K fertilizer significantly reduced the ABA content of flower bud;N,K fertilizer significantly reduced the IAA content;K fertilizer significantly reduced the GA₃ content.In the pistil and stamen formation stage,N,P and K fertilizer significantly reduced the ZR content of flower bud;N,P and K fertilizer significantly reduced the ABA content;N,K fertilizer significantly reduced the IAA content;the content of GA₃ was significantly increased by N and K fertilizer.In the ovary and anther formation stage,the content of ZR and IAA were significantly increased by N and K fertilizer;N and P fertilizer significantly increased the GA₃ content of flower bud;In the pistil and stamen mature stage,the content of ZR was significantly increased by N and K fertilizer;N,P and K fertilizer significantly reduced the ABA content of flower bud;P and K fertilizer significantly increased the IAA content;N and K fertilizer significantly increased the GA₃ content.（4）In the test fertilization level,the net photosynthetic rate and SPAD values of Camellia oleifera leaves could be improved by applying N,P and K fertilizer in a moderate amount;It significantly improved the stomatal conductance of Camellia oleifera leaves by applying a proper amount of P fertilizer.The amount of N fertilizer significantly increased the concentration of intercellular CO₂ in the leaves of Camellia oleifera.N and P fertilizer significantly improved the transpiration rate of Camellia oleifera leaves.N,P and K fertilizer significantly improved the water use efficiency of Camellia oleifera leaves.In the test fertilization level,the activities of SOD in Camellia oleifera leaves could be increased by appling appropriate amount of N and K fertilizer,and appling appropriate amount of N,P and K fertilizer increased the activities of POD in Camellia oleifera leaves.（5）Correlation analysis of flower bud determination standard:In the predifferentiation stage,ZR showed a highly significantly positive correlation with IAA;ABA was significantly positively correlated with flower bud differentiation rate,and ABA was significantly positively correlated with GA₃.In the sepal formation stage,ZR showed a highly significantly positive correlation with IAA and GA₃;ABA was significantly positively correlated with IAA;IAA showed a highly significantly positive correlation with GA₃;In other flower bud differentiation stage,ZR showed a highly significantly positive correlation with IAA and GA₃;IAA showed a highly significantly positive correlation with GA₃;In the predifferentiation stage,ZR and IAA showed a significantly positive correlation with mixed bud length;ABA showed a significantly negative correlation with mixed bud length;In the sepal formation stage,ABA showed a significantly positive correlation with mixed bud width;GA₃ showed a significantly negative correlation with mixed bud width;In the pistil and stamen formation stage,ABA showed a significantly positive correlation with mixed bud width and a highly significantly positive correlation with mixed bud length.In the ovary and anther formation stage,ABA showed a significantly positive correlation with mixed bud width;GA₃ showed a significantly negative correlation with mixed bud length;Correlation analysis of physiological and biochemical determination standard:The SPAD value of Camellia oleifera leaves was significantly positively correlated with the stomatal conductance G_s.The net photosynthetic rate P_n was extremely significantly positively correlated with the stomatal conductance G_s.There was a highly significantly negative correlation between P_n and intercellular CO₂ concentration Ci.The net photosynthetic rate P_n was significantly positively correlated with transpiration rate T_r.The stomatal conductance G_s was significantly positively correlated with transpiration rate T_r.Intercellular CO₂ concentration Ci,transpiration rate T_r was highly significantly negatively correlated with water use efficiency WUE.P_n was significantly negatively correlated with ZR/GA₃;T_r was highly significantly negatively correlated with ABA/IAA and ZR/IAA;G_s was significantly negatively correlated with ZR/IAA;WUE was significantly positively correlated with ZR/IAA;ABA was highly significantly negatively correlated with SOD and POD activity.GA₃ was significantly positively correlated with SOD activity;ABA/GA₃ and ZR/ GA₃ was highly significantly positively correlated with SOD and POD activity;ABA/IAA was significantly negatively correlated with POD activity.（6）In this study,a mathematical model of N,P,K fertilization was established to obtain the following four of the optimum ratio of N,P,K fertilization（the following fertilizer ratio unit was g per tree）:the optimum ratio of N,P,K fertilization was N_222.22P_81.83K_240.24 for increasing the rate of Camellia oleifera flower bud differentiation;the optimum ratio of N,P,K fertilization was N_155.68P_83.54K_232.5 for increasing the net photosynthetic rate of Camellia oleifera leaves;the optimum ratio of N,P,K fertilization was N_125.07P_75.12K_226.68 for increasing SOD activities of Camellia oleifera leaves;the optimum ratio of N,P,K fertilization was N_145.20P_72.42K_240.74 for increasing POD activities of Camellia oleifera leaves.