果实乃日中储水库:一个长期争议的问题(英文)

Fruit as a midday resevoir:solving a controversial problem

20世纪初创立的所谓"果实乃日中储水库"的理论,在70—80年代受到了挑战。反对者认为原来理论创立者所采用的是切枝试材而非完整植株,属于试验方法上的错误。他们怀疑切枝试材会迫使形成一种非自然的水势梯度,导致蒸腾的叶片能够从果实获取水分。本文报道氚水示踪法在完整植株上的试验结果,证明果实的水分完全可以被叶片抽走,此外,"去果实"和"留果实"的对比试验证明果实的存在有利于降低叶片在昼间的缺水程度,即叶水势相对较高。作者指出果实在夜间对水分的竞争力往往超过叶片,所以结果多的果树植株反而容易受旱而死。因此,单纯把果实比喻为"储水库",作为科学用语似不恰当。

The so-called ＂fruit as a midday reservoir＂ theory was queried and challenged in the 1970＇s and 1980＇s by the reason that the experimental methods the previous researchers used instead of intact plants were excised shoots, which might induce the development of unnatural water potential gradients. The present authors conducted experiments with potted and field-grown citrus plants with both tritium tracing and water potential measurements to verify the assumption that transpiring leaves are capable of drawing water directly from fruit. Translocation of tritiated water was detected fi＇om fruit to leaf, and the presence of fruit on a shoot might moderate, whereas the absence of fruit might accentuate the leaf water deficits during the day-time. It is pointed out that fruit may not necessarily be inferior to the leaves, as fruit may compete successfully with leaves for water during the night-time when their water potentials become lower than that of the leaves. It is considered that the figurative use of the word ＂reservoir＂ as a scientific jargon does not appropriately denote the actual behaviours of a living fruit.