There has recently been a resurgence in interest in the photosynthetic efficiency of apple (Malus domestica Borkh.) trees. During the 1930’s and early 1940’s several papers were published relating to leaf morphology and the effects of various factors such as water relations, nutrition, and pesticides on net photosynthesis (Pn) of apple leaves. From the mid 1940’s until the mid 1960’s little relevant research was published. Renewed emphasis began to be apparent by the mid 1960’s, partially as the result of greatly improved equipment, particularly the infrared gas analyzer (IRGA). This discussion is devoted to the maximum net photo synthetic potential of apple leaves, the factors which have been shown to influence it, and areas which need further research if we are to fully exploit the inherent capability for CO2 fixation.
Received for publication February 28, 1978.
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