陈菁+陆超忠+石伟琦+冼皑敏+赵大宣+王文林+覃振师

摘 要 為实现澳洲坚果的精准施肥，本研究以4、8、25 a的H2澳洲坚果树为试材，采用个体收获法，采集以树干为中心，树冠滴水线外约10 cm处（与其他树树冠交叉处）为边的整个圆内的不同距离、不同土层根系，并按其大小进行分级，清冼晾干后测其直径大小、鲜重和水分系数，分析根系在土层内的分布特点。结果表明：（1）4、8 a树0～20 cm土层根系干重显著高于其他层次，而25 a树20～40 cm土层根系分布最多，3种树龄0～40 cm土层根系干重占总根干重比例大于72%；（2）8、25 a树0～20 cm土层末级根干重占总末级根干重比例约为60%，而4 a树仅为44.8%；（3）4、8 a树离树干0～50 cm范围总根干重显著高于>50 cm外总根干重，而25 a树>50 cm外根干重显著高于0～50 cm范围内根干重，并且8、25 a树>50 cm末级根干重占总末级根重比例高于90%，而4 a树则高于68%；（4）除了末级根，3种树龄根系干重基本上是随着根直径减少而减少。

关键词 澳洲坚果 ；根系 ；分布

中图分类号 S664 文献标识码 A Doi：10.12008/j.issn.1009-2196.2017.06.005

The Distribution Features of Macadamia Roots

CHEN jing1） LU Chaozhong1） SHI Weiqi1）

XIAN Aiming1） ZHAO Daxiang2） WANG Wenlin2） QIN Zhengshi2）

（1 South Subtropical Crops Research institute of CATAS/ Hainan Key Laboratory

of Crops Nutrition， Zhangjiang， Guangdong 524091；

2 Guangxi Research Institute of South Subtropical Agriculture， Longzhou， Guangxi 532400）

Abstract In order to achieve the precise fertilization of macadamia， troots were sampled from 4， 8 or 25 years old macadamia trees （cv.H2） by the way of individual harvesting from different soil layers and from different distance within a circle of 10 cm out of the dripping line of the canopy of macadamia trees. The roots were graded into different sizes. All the samples were weighed after washed， and their water contents were determined. The root distribution was analyzed. The results showed that the dry weight of roots collected from the soil 0 to 20 cm deep in the 4 and 8 years old trees was significantly higher than that collected from the soil of other depths. The number of roots from the soil 20 to 40cm deep was the highest in the tree at the age of 25 years old. For the 4， 8 and 25 years old trees the dry weight of roots from the soil 0 to 40cm deep took up more than 72% of the dry weight of total roots. The dry weight of the lateral roots from the soil 0 to 20cm deep contributed almost 60% to the dry weight of total lateral roots for the 8 and 25 years old trees， and was only 44.8% of that of the total for the 4 years old trees. The dry weight of total roots 0 to 50cm away from the trunk base was greater than that >50 cm away from the trunk base in the 4 and 8 years old trees， while the dry weight of total roots >50 cm away from the trunk base was greater than that 0 to 50 cm away in 25 years old trees. The dry weight of lateral roots >50 cm away from the trunk base made up more than 90% of the dry weight of the total lateral roots in the 8 and 25 years old trees， and was greater than 68% in the 4 years old trees. The dry weight of roots from of the 4， 8 and 25 years old trees decreased with the root diameter except the lateral roots.

Keywords macadamia ； root ； distribution

澳洲坚果（Macadamia integrifolia）又名夏威夷果，原产澳大利亚[1]，其人工栽培历史仅150多年，是一种新兴果树[2]。我国澳洲坚果产业起步较晚，但由于近年来澳洲坚果市场需求日益扩大，我国的澳洲坚果产业发展迅速，目前我国的栽培面积已超过10万hm2[3]。大面积澳洲坚果栽培，迫切需要良好的栽培技术作为支撑，明确其根系分布特点是实现澳洲坚果合理施肥的重要基础性工作。

陆超忠等[4]曾做过根系在土壤中生长及分布调查，但此研究只是挖剖面进行根系数目调查，并未对澳洲坚果全部根系分布进行调查，对水分养分吸收起主要作用末级根也未作单独调查分析。本研究……