在58年以前,我们用铁桶运输杨树种子,经过几年来的应用发现有两个缺点:一、薄铁缺乏而且昂贵,大量制造铁桶不仅材料困难并且开支大;二、每年调运空桶时,不但要支付大量运费(空桶按容积计算运费),而且浪费运输力量。为了克服以上缺点,我们在58年采种 58 years ago, we used poplar to transport poplar seeds. After years of application, we found two shortcomings: First, the thin iron is lacking and expensive. It is not only difficult to produce materials in large quantities, but also expensive. Second, When not only to pay a large number of shipping costs (empty barrel according to the volume of freight), but also a waste of transport power. In order to overcome the above shortcomings, we planted in 58 years