各种树木体内分泌的化学物质（气体或汁液），有的相生，有的相克。在植树造林时，如果能利用这些相生相克的关系，趋利避害，将对丰产丰收起到意想不到的效果。苹果和樱桃：这两种树种植在一起，能结出更香更甜的果实。梨树与桧柏：梨树林周围五公里内不能栽种桧柏。否则，容 A variety of chemical substances secreted by the trees (gas or juice), some of the symbiosis, and some g. In afforestation, if we can make use of these relations, we can find the benefits and the avoidance will have an unexpected effect on the high yield. Apples and cherries: The two trees are planted together to produce more fragrant and sweeter fruit. Pear and cypress cypress: pear forest can not plant cypress within five kilometers. Otherwise, tolerance