title: Effect of CPPU on Carbohydrate and Endogenous Hormone Levels in Young Macadamia Fruit.
abstract: N-(2-Chloro-4-pyridyl)-N'-phenylurea (CPPU) is a highly active cytokinin-like plant growth regulator that promotes chlorophyll biosynthesis, cell division, and cell expansion. It also increases fruit set and accelerates fruit enlargement. However, there has been no report about the effect of CPPU on fruit development and its physiological mechanism in macadamia. In this study, we investigated the effect of CPPU treatment at early fruit development via foliar spray or raceme soaking at 20 mg·L-1 on fruit set and related physiology in macadamia. Changes in carbohydrate contents and endogenous hormones in leaves, bearing shoots and fruit were also examined. Results showed that CPPU significantly reduced young fruit drop and delayed the wave of fruit drop by 1-2 weeks. The treatment significantly decreased the contents of total soluble sugars and starch in the leaves, but increased them in the bearing shoots and total soluble sugars in the husk (pericarp) and seeds. These findings suggested that CPPU promoted carbohydrate mobilization from the leaves to the fruit. In addition, CPPU increased the contents of indole-3-acetic acid (IAA), gibberellin acid (GA3), and zeatin riboside (ZR) and decreased the abscisic acid (ABA) in the husk. Therefore, CPPU treatment reduced the early fruit drop by increasing carbohydrate availability and by modifying the balance among endogenous hormones.
authors.affiliation: College of Horticulture, South China Agricultural University, Guangzhou, Guangdong, China.|South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, Guangdong, China.|Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, Zhanjiang, Guangdong, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zeng
authors.affiliation: South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, Guangdong, China.|Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, Zhanjiang, Guangdong, China.
authors.forename: Weihai
authors.initials: W
authors.lastname: Yang
authors.affiliation: South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, Guangdong, China.|Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, Zhanjiang, Guangdong, China.
authors.forename: Chaozhong
authors.initials: C
authors.lastname: Lu
authors.affiliation: South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, Guangdong, China.|Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, Zhanjiang, Guangdong, China.
authors.forename: Wenqiu
authors.initials: W
authors.lastname: Lin
authors.affiliation: South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, Guangdong, China.|Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, Zhanjiang, Guangdong, China.
authors.forename: Minghong
authors.initials: M
authors.lastname: Zou
authors.affiliation: South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, Guangdong, China.|Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, Zhanjiang, Guangdong, China.
authors.forename: Hanzhou
authors.initials: H
authors.lastname: Zhang
authors.affiliation: South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang, Guangdong, China.|Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, Zhanjiang, Guangdong, China.
authors.forename: Jifeng
authors.initials: J
authors.lastname: Wan
authors.affiliation: College of Horticulture, South China Agricultural University, Guangzhou, Guangdong, China.
authors.forename: Xuming
authors.initials: X
authors.lastname: Huang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D002241:Carbohydrates / Q000737:chemistry*; D003583:Cytokinins / Q000378:metabolism; D005638:Fruit / Q000187:drug effects* / Q000378:metabolism; D005875:Gibberellins / Q000378:metabolism; D039106:Macadamia / Q000187:drug effects* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry*; D012639:Seeds / Q000187:drug effects
chemical_list: D002241:Carbohydrates; D003583:Cytokinins; D005875:Gibberellins; D010937:Plant Growth Regulators; D011140:Polyurethanes; C030554:co(polyether)polyurethane; D011092:Polyethylene Glycols; D000040:Abscisic Acid