自1877年将巴西橡胶由巴西引到远东热带地区以来,继续进行选育种的结果已使胶乳产量显著提高。由于许多胶园利用现代的种植材料,现在每(口亩)橡胶平均年产量已超过1,000磅。现代无性系的每(口亩)年产量可达2,000磅以上,而本世纪初用的实生苗材料,每(口亩)年产橡胶不 Since the introduction of Brazilian rubber from Brazil into the Far East tropics in 1877, the continued selection and breeding has resulted in a significant increase in latex production. With many rubber plantations using modern plantings, the average annual output of rubber per mu has now exceeded 1,000 pounds. Modern clones have an annual output of more than 2,000 pounds per acre, whereas seedlings used for the beginning of this century have an annual output of rubber per mu