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测定苹果叶片净光合率(Pn)的技术有几种,但都存在着一些问题。像Heinicke等人所做的封住整株树,这在需要多次重复时实际上很难办到。另外的问题是难于表现出光合有效辐射水平,不易确定叶面积,很难保证树冠内足够的和一致的气流。Heinicke设计出一套活动的实验装置,可用来在果园的树上测定单叶。Seeley等研制了一套精巧的装置,可以将一树枝封住,並能控制住气候的变化。但是即使用这个装置,在阴雨潮湿的天气,也很难取得数据。
There are several techniques for determining the net photosynthetic rate (Pn) of apple leaves, but there are some problems. Enveloping the whole tree like Heinicke et al. Is actually very difficult to do when multiple repetitions are needed. Another problem is that it is difficult to show the level of photosynthetically active radiation, the leaf area is not easy to determine, and it is difficult to ensure adequate and consistent airflow within the crown. Heinicke devised an experimental set of activities that can be used to determine single leaves in orchard trees. Seeley and other developed a sophisticated device that can seal a branch, and can control climate change. But even with this device, in wet and rainy weather, it is difficult to obtain data.