Effects Of Fertilization And Shading Leaf Colour Expression Of Sapium Sebiferum

This article carried out two tests,e.g.foliar fertilization and shading treatments,which explore the effect of foliar fertilization and shading on leaf colour.This experiment examine the content of chlorophyll,anthocyanin,carotenoid,and soluble sugar,as well as leaf colour parameters（brightness L *,redness a *,and yellowness b *）,and activities of enzymes（phenylalanine ammonia lyase PAL and chalcone isomerase CHI）.The plants were treated with of 0.5% KH₂PO₄,0.5% nitrogen fertilizer,and water,spraying once every 7 days with a total of 5 times.Samples were taken every 7d at 9 am and selected from new leaves of the functional leaves of each plant.Each individual was repeated three times for each index.The test results showed that foliar application of KH₂PO₄ elevated the contents of chlorophyll,anthocyanin,and soluble sugar,as well as the activities of PAL and CHI.The anthocyanin contents were significantly correlated with PAL and CHI activities with correlation coefficients of 0.98 and 0.93（p<0.05）respectively.Leaf colour parameter values of brightness L *,redness a *,and yellowness b * were overall upward trend,making the brightness of Sapium sebiferum leaves increased,and red leaf colour was bright.Nitrogen fertilizer could promote the synthesis of chlorophyll,but had no significant effect on the content of anthocyanin,soluble sugar,and PAL and CHI activities,and decreased the ratio of anthocyanin / chlorophyll.The nitrogen fertilizer treatment reduced the values of brightness L * and redness a *.The leaf brightness decreased and the leaf colour was dark green.KH₂PO₄ treatment increased the contents and reabsorption efficiency parameters of N,P,and K nutrients,while nitrogen fertilizer enhanced the contents of N and P and attenuated the contents of K and the nutrient reabsorption efficiency of N,P and K.The shading net with a shading degree of 25% was selected.One and two layers of shading net were used for the shading treatments of 25% and 50% respectively,and the whole light was a control.At 9 o’clock on the 7th day,the third new leaf of the young shoots was sampled each time.Each sample was repeated three times for each index.The chlorophyll content was higher for the 50% shading treatment than for the 25% shading treatment,while the contents of anthocyanin and soluble sugar were lower for the 50% shading treatment than for the 25% shading treatment.Shading treatment reduced the activity of the two enzymes.The correlation analysis showed that the correlation between PAL activity and anthocyanin content was significant（p<0.05）,and the correlation between CHI activity and anthocyanin content was not significant.The values of brightness L * and the redness a * after the shading treatment were gradually decreased,making a reduced brightness of the blade and dark green leaf colour.Shading treatment to increased the contents of N,P elements,and reduced the K element contents and N,P,K nutrient reabsorption efficiency.