Collection, storage and handling of plant genetic resources and their global distribution are essential components of international crop and tree improvement programmes.
植物遗传资源的收集、存储和处理以及它们在全球的分布，是国际作物和树木改良计划的重要成分。
2
Meanwhile, pests such as tree-killing beetles and crop-killing fungi will both increase their range and breed more rapidly.
同时，专杀树林的甲壳虫和专杀作物的真菌都会扩大活动范围，也会更加迅速繁殖。
3
Pecans are the only major tree nut native to the U.S., which produces about 80 percent of the world's crop.