大约400种：在温带的亚洲，非洲和美国主要热带和亚热带，很少；中国有34种。
About 400 species: mostly tropical and subtropical, few in temperate Asia, Africa, and America; 34 species in China.
拉美国家产量通常很低，但科学研究已证明高产稳产在热带和亚热带地区已有可能。
In general, crop yields in Latin American countries are low but scientific research has demonstrated that high sustainable yields are possible in tropical and subtropical areas.
拉美国家产量通常很低，但科学研究已证明高产稳产在热带和亚热带地区已有可能。
In general, crop yields in Latin American countries are low but scientific research has demonstrated that high sustainable yields are possible in tropical and subtropical areas.
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