桑树干重的90-95%是绿叶进行光合作用,固定二氧化碳的产物。桑园生物学产量取决于桑园叶面积指数、叶片光合作用强度或净同化率、叶片光合时间和树体呼吸消耗等这四个因素。为了提高产量,就要采取措施,使前三个因素尽可能地增大,而使后面一个因素尽可能地变小。在这些因素中,叶面积变化最大,通过栽培措施比较容易控 90-95% of dry weight of mulberry is the product of green leaf photosynthesis, carbon dioxide fixation. Mulberry biological yield depends on the mulberry leaf area index, leaf photosynthesis intensity or net assimilation rate, leaf photosynthetic time and tree respiration consumption of these four factors. In order to increase output, measures must be taken to make the first three factors as large as possible and the latter factor as small as possible. Among these factors, the leaf area has the largest change and is easier to control through cultivation measures