Substrate utilization and respiration in relation to growth and maintenance in higher plants

The significance and regulation of respiration in plants was investigated to determine how much C fixed by photosynthesis was lost during respiration. Relationships between growth, substrate utilization and maintenance were accurately calculated on theoretical grounds; results were in close accordance with experimental results for dark-grown maize embryos. Energy absorption by leaves was often 10-15% higher than expected mainly because at light saturation, surplus energy could be used for nitrate reduction. Comparisons of measured and calculated assimilation:dissimilation ratios in young plants indicated that substrates were used at their biochemically maximum efficiency. Maintenance processes required relatively low amounts of energy in rapidly growing tissues (>0.3 g/g day) but considerable proportions in other tissues, and were difficult to measure. (Abstract retrieved from CAB Abstracts by CABI’s permission)