Corn Growth Response to Temperature: Rate and Duration of Lead Emergence
- J. D. Hesketh and
- I. J. Warrington
Seasonal predictions of gas and energy exchange in crop canopies require a quantitative description of temperature effects on leaf area development. Such predictions are needed in crop management and forecasting models. Our objectives were to quantify temperature effects on leaf emergence rates, determined as lengths and areas of fully expanded emerged leaf material, and their duration in corn (Zea mays L.). Hybrids were grown in controlled environments under 16 temperature regimes ranging from 16/11 to 38/33 °C (124 day/night thermal periods). Plants were dissected every 3 to 10 d, depending on the temperature, to determine the mainstem node number associated with the youngest leaf primordium as well as weight, area, and length per leaf. The node number of the youngest leaf showing a ligule was recorded. Leaf emergence rates, either as lengths or areas per unit time, and the node associated with the youngest visible leaf tip were derived from time plots of emerged leaf lengths and area. Emergence duration was estimated three ways: (i) the time between appropriate leaf developmental events, from time plots, (ii) mature leaf length divided by its extension rate, and (iii) mature leaf area divided by its area emergence rate. Primordia and ligule appearance rates derived from these data were published earlier. The relationships between temperature and tip appearance rates, leaf emergence rates, and the reciprocals of the various estimates of duration were determined; threshold temperatures and degree day requirements for processes derived from such plots are presented. Other information is provided for developing logic for predicting temperature effects on the development of canopy leaf area in corn.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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