Night respiration of a maize crop in the lowland humid tropics.
Overnight respiration losses of whole plants were measured in a young maize crop grown in the humid tropic zone of Western Nigeria. In an older crop, overnight leaf respiration was measured. In the younger plants, respiration rates initially were high (c. 15% overnight reduction in dusk plant dry wt.) but declined to c. 5% by 27 days after emergence. Overnight leaf respiration caused 4% reduction in dusk lamina dry wt. Nightly dry wt. losses by whole plants averaged 40% of daily dry wt. gain. Assuming a value of 12 mg/g per 12 h with a Q10 of 2 for the maintenance component of respiration for the period 11 to 27 days after emergence, overnight dry wt. loss could be reduced to 37% and 35% of daily gain for a 10 deg and 20 deg C decrease in night min. temp. Such dry wt. conservation, if maintained through the remaining period of crop growth, could give yield increases of 200 and 300 kg/ha, resp., and at best c. 5% improvement on Experimental Station yields of elite cv. On this basis it appeared that high night temp. are of minor importance in explaining yield differences between the humid tropics and temperate zones.