Dry Matter Production by Detached Ears of Wheat

Abstract

CEREAL yields have been shown to depend more on assimilation in the ears and flag leaves than on translocation into the grain of compounds manufactured or stored in other green parts of the plant¹. Quantitative estimates of the relative contributions from the ears, the flag leaves or other green parts have been made by shading and defoliation methods^2–6, by enclosing ears in a transparent chamber supplied with ¹⁴CO₂ (ref. 7), or by following changes in the carbon dioxide content of air-streams entering and leaving such a chamber⁸. Such methods have been criticized for various reasons^9,10. Buttrose and May⁹ claimed that their technique with regulated floret numbers is free of many of these disadvantages, but Thorne⁸ has shown that one of the assumptions on which the method is based is not valid and Lupton¹¹ has demonstrated that different results can be obtained if different numbers of florets are left on the ear. Obviously, this method of measuring net assimilation of cereal ears is also open to criticism.