Study Of Plant Growth Regulators On The Effect Of The Growth And Fruit-set Of Apple And Distribution, Utilization Of C And N

1.One-year-old potted Malus hupehensis Rehd. seedlings with 15 N trace technique were used to study the effect of plant growth regulators on plant growth and the absorption, utilization, and distribution. The main results were as follows: the growth of the Malus hupehensis Rehd. seedlings were effectively promoted when NAA and 6-BA were applied. The plant root activity, 15 N distribution to root and 15 N utilization efficiency of NAA were significantly higher than CK, with the optimal concentration of NAA was 10 mg · L-1; the plant height, 15 N root distribution rate and 15 N utilization efficiency of 6-BA were significantly higher than CK, with the best amount of 6-BA was 150 mg · L-1; when ethrel was applied, the plant root activity and 15 N distribution of roots rate were significantly higher than CK, and no significant difference was seen among different concentrations.2.5-year-old apple trees(Yanfu 3/M26/Malus hupehensis Rehd.) were treated with three different plant growth regulators to study the effect on fruit setting, which were α-Naphthalene acetic acid(NAA,10 mg · L-1), Ethrel(600 mg · L-1) and 6-Benzylaminopurine(6-BA, 100 mg · L-1) respectively, and all the trees were labeled with 13 C and 15 N to determine the characteristics of carbon and nitrogen utilization. The results showed that fruit-set rate was obviously lower than control when sprayed with 10 mg · L-1 NAA and 600 mg · L-1 Ethrel 14 days after bloom, while no significant difference was found on spraying 100 mg · L-1 6-BA treatment. The 13 C and 15 N distribution to fruits of NAA and Ethrel treatments were 1.11%,1.22% and 0.39%,0.33% respectively, which were lower than control(9.12%,7.29%), while the 13 C allocation to roots and branches were higher than control significantly. Similar regulation can be seen on Ndff of NAA and Ethrel treatments, the treatments improved the leaves, roots and branches duty ability of 15 N, and reduced the fruits duty ability of 15 N. The 15 N utilization rate was increased by 2.35% and 2.37% respectively when sprayed NAA and Ethrel compared with control, and the treatments promoted the vegetative growth and the duty ability of N photosynthate of the roots, leaves and branches, while no significant difference was found on the 15 N utilization of 6-BA treatment,it may be related to different apple varieties,different concentration of plant growth regulators, and different time of treatment and reaction.