Effects Of Dopamine And Melatonin On Young Apple Trees’ Growth

Apple (Malus pumila) is one of dominant cultivating fruit in China, and the apple’s yieldof China is biggest in the world. Apple trees’ growth will be affected by the externalenvironment. Therefore, to improve apple trees`fitness on the external environment can become true by improving the stress resistance, and may show a significant meaning onincreasing the yield. Dopamine and melatonin has strong antioxidant capacity, can improveplant’s stress resistance. Further more, spraying dopamine and melatonin on apple trees`growth period can affect apple’s growth and development. In this study, the material wasnewly planted Fuji apples at Luochuan, Shaanxi, we compared the influence on growth massand leaf mass by spraying different concentrations of dopamine and melatonin solution. Hereare the results obtained:1.100and200μmol/L solution of melatonin could promote the growth of apple. Afterwatering treatment for6months, the young apple trees growth mass and leaf mass washeavier than the control group. Particularly, the group which watered by200μmol/L solutionof melatonin showed a significant different compared with the control group, trunk diameter,height, spur and long branch length, number of lateral branches, total chlorophyll content,chlorophyll a, b, the content of carotenoids, specific leaf weight and heavy blinds haveincreased6.7%,2%,8.4%,4.6%,27.6%,10.8%,12%,6.7%,4%,8.1%and6.2%. However,the100μmol/L solution of melatonin showed a relatively little promotion for the indexes.The400μmol/L solution of melatonin was shown to inhibit growth, both leaf mass andgrowth mass decreased significantly compared with the control group.2.50μmol/L solution of dopamine could promote the growth of apple saplings. Aftersix months of treatment, the growth mass and leaf mass of the saplings had improved, Trunkdiameter, height, spur and long branch length, number of lateral branches, total chlorophyllcontent, chlorophyll a, b, the content of carotenoids, specific leaf weight and heavy blindshave increased1.2%,0.4%,2.1%,8.8%,7.8%,8.6%,7.5%,13.5%,3.2%, and2%. As a result,50μmol/L dopamine solution has the similar effect as100μmol/L melatonin solutioncan, lessthan200μmol/L melatonin solutioncan.Meanwhile, the100and200μmol/L solution ofdopamine exhibited a significant inhibitory effect, which the higher the concentration, themore significant inhibitory. 3. Synthetically, spraying appropriate concentration of exogenous melatonin anddopamine could promote the growth of apple trees. The concentration of100to200μmol/Lsolution of dopamine or the concentration of less than50μmol/L solution of melatonin hadthe best effect to enhance the growth of apple trees.