Responses Of Growth And Leaf Coloring Of Cotinus Coggygria To Combined N,P And K Fertilization

Cotinus Coggygria is an important ornamental shrub species on both sides of the Yangtze River in the Three Gorges Reservoir region.Its growth condition and leaf color quality directly affect the ornamental effect and the development of tourism,but poor soil has an effect on its growth and development.To this end,using chemical nitrogen?N 0,5,10 g/kg?,phosphorus?P 0,12.5,25 g/kg?,and potassium?K 5,10,15 g/kg?and set 10 treatments in this study,the growth?includ plant Height,ground diameter,ratio of plant height to stem,leaf length,leaf width,leaf length-to-width ratio and leaf area?,photosynthetic characteristics?include photosynthetic pigment content,diurnal variation of photosynthetic parameters and light response curve?and leaf color indexes?include leaf color parameter,leaf pigment content,soluble protein and soluble sugar content,leaf phenylalanine ammonia-lyase activity and leaf pH value?were measured under different fertilization conditions,The relationship between N,P and K,growth and leaf color of C.Coggygria was analyzed,and the optimum formula was found within the scope of this test.It provided the theoretical basis for the scientific fertilization management of C.Coggygria.It is great significance to solve the problem of growth potential difference and dull leaf color of C.Coggygria.The results of this study were as follows:?1?N,P and K combinations significantly increased the height and diameter of C.Coggygria,reduced the ratio of height to diameter,increased leaf length,leaf width and leaf area,and promoted the growth of C.Coggygria.The growth in each of the treatments was as follows:The total increase of plant height ranged from 38.00±4.09 cm to 68.67±4.51 cm,and the total increase of plant height of T3?N₁P₃K₃?and T9?N₃P₃K₂?were significantly higher than that of control?P<0.05?.The total increment of ground diameter ranges from 0.47±0.06 cm to 1.17±0.24 cm,Except T5?N₂P₂K₃?and T7?N₃P₁K₃?,there were significant differences between the treatment and the control?P<0.05?.The total increment of height to diameter ratio was 246.99±21.84 to 357.99±31.02.Fertilization could significantly reduced the height to diameter ratio?P<0.05?.The total leaf length increase ranged from 49.04±5.65mm?88.77±8.65 mm,and the leaf length increase from July to September was the largest,and T6?N₂P₃K₁?and T7 were significantly higher than the control?P<0.05?.The total increase of leaf width ranged from 15.32±1.26 mm to 44.87±3.57 mm,and the increase of leaf width was the largest in the period of March to May under fertilization,with significant difference between T9 and control?P<0.05?.The total leaf area increased from 2275.77±109.3mm² to 4623.22±215.37mm²,and the leaf area increased the most from March to May,and the leaf area increased significantly in all fertilization treatments?P<0.05?.The fertilizer contribution rate was N>P>K,N and K were the main factors affecting plant height and leaf area,P was the main factor affecting ground diameter.?2?N,P and K combinations significantly increased the leaves of photosynthetic capacity of C.coggygria.1)Photosynthesis of C.coggygria leaves was measured in mid-august 2018,the results showed that:the net photosynthetic rate?P_n?and stomatal conductance?G_s?of all treatments showed a peak value at about 9:00 and 13:00 respectively.Except for T2?N₁P₂K₂?,the daily average value of P_n of the other treatments was significantly higher than that of the control?P<0.05?;The mean daily G_s of T9 was significantly higher than that of control?P<0.05?.The transpiration rate?T_r?peaked around 11:00,and the daily average values of T5,T6and T9 were significantly higher than those of the control?P<0.05?.The light energy use efficiency?LUE?of all treatments decreased firstly and then increased.All fertilization treatments were significantly higher than control?P<0.05?.2)Except for T2 and T4?N₂P₁K₂?,the apparent quantum efficiency?AQY?of the other treatments was significantly lower than that of the control?P<0.05?.Among them,the decrease of T4,T7 and T9 was the largest,and the difference of P_nmax of the other treatments was significant?P<0.05?;except T1?N₁P₁K₁?,T2 and T7,the light saturation point?LSP?of T3,T8?N₃P₂K₁?and T9 was significantly higher than that of the control?P<0.05?,the light compensation point?LCP?of all treatments except t1 was significantly different from that of the control?P<0.05?;The dark absorption rate?Rd?of T2,T5 and T9 was significantly higher than that of control?P<0.05?.The contribution rate of fertilizer was P>N>K,in which P had a great effect on photosynthetic pigments?Chl s and Car?,and had a positive correlation with P_n,P_nmax and LSP.N and K had great influence on LUE,and LUE was positively correlated with LCP,T_r and G_s.?3?N,P and K combinations increased the leaves coloring effect of C.coggygria.Samples were taken on May 10?incipient stage?,August 10?growth Spurt stage?,November5?initial color change stage?,November 20?mid-discoloration stage?,and December 5,?terminal discoloration stage?,2018.The results showed:The leaf color parameter L*was the lowest in the growth spurt stage,and a*value rose gradually with time,in which the rising trend was increased from mid-discoloration stage to terminal discoloration stage,the highest value was reached at terminal discoloration stage,and the value of b*was the lowest at growth spurt stage,and then rose gradually.The total average values of color C*of T1,T2and T3 were significantly higher than those of control?P<0.05?.The changes of physiological indexes were as follows:The total chlorophyll content?Chls?ranged from 0.05±0.00 mg/g to 4.71±0.38 mg/g,and the content of Chls was the highest in the growth spurt stage,among which,T6,T7,T8 and T9 were significantly higher than the control?P<0.05?;The total content of Carotenoid ranged from 0.45±0.07 mg/g to 5.32±0.19 mg/g,and reached the highest value in growth spurt stage,T7,T8 and T9 was significantly higher than that of the control?P<0.05?,the content was the lowest at the initial color change stage,after entering the period of discoloration,there was no significant difference between fertilizer and control?P>0.05?;The content of total anthocyanin?Ant?ranged from 1.81±0.46 U to157.20±13.71 U,and reached the maximum at terminal discoloration stage,and T5,T6 and T9 were significantly higher than those of the control?P<0.05?;The content of Soluble Protein?SP?was relatively low at terminal discoloration stage,T6,T7,T8 andT9 were significantly higher than those of the control?P<0.05?;the contents of soluble sugar?SS?were the highest in growth spurt stage,and the contents of T4 and T7 were significantly higher than in the control?P<0.05?,T4 was significantly higher in mid-discoloration stage,in terminal discoloration stage,all treatmentsexcept T1 were significantly higher than control?P<0.05?;the activity of Phenylalanine ammonia-lyase was the highest at terminal discoloration stage,except for T1,all the treatments were significantly higher than the control?P<0.05?;the pH value of leaves was relatively low at incipient stage,and was highest at initial color change stage,T3 and T8 were significantly higher than T10?P<0.05?.The contribution rate of fertilizer was N>P>K,N and k were the main factors affecting Chls and Car,P was the main factor affecting Ant.Ant was the key factor for C.coggygria leaves to appear red,and had positive correlation with PAL activity and negative correlation with SP and SS.In conclusion,the reasonable of N,P and K can not only promote the growth of C.Coggygria,but also improve the color quality of the leaves,the contribution rate to them was N>P>K,Anthocyanin?Ant?was the key factor for the red color of C.coggygria leaves,and the activity of PAL,and the contents of SS and SP can promoted the synthesis of Anthocyanin.According to the membership function value,within the scope of this test,T8?N,P and K applying amounts of 15,12.5,5 g/plant,respectively?,and T9?N,P and K applying amounts of 15,25,10 g/plant,respectively?were the best fertilization rates for promoting the growth and improving the leaf color.Therefore,it can solve the problems of growth potential difference and dull leaf color of Cotinus Coggygria with N,P and K,and improve the ornamental value of leaves.