An analysis of the growth of young tomato plants in water culture at different light integrals and CO2 concentrations: I. Physiological aspects

Abstract

Young tomato plants were grown from germination in water culture at light-flux densities from 6 to 110 W m-2 (400-700 nm), daylengths from 8 to 24 h and CO2 concentrations from 0.4 to 2.2 g CO2 m-3 in controlled environment cabinets.The growth rates and net assimilation rates of 14-17-day-old plants at the highest light integrals were appreciably greater than most values previously recorded for tomato, and diminished with time. Plants in the lowest light conditions had leaf area ratios five times larger than those in the highest light, attributable mainly to a difference in leaf dry weight/area. Such flexibility in leaf area ratio has not previously been associated with 'sun' plants such as the tomato.Relatively normal growth was obtained in continuous light, in contrast to most other reports. This may have been due to the use of conditions which would minimise water stress.The efficiency of the conversion of incident light energy to chemical energy by the whole plant ranged from 15 per cent in seedlings in low continuous light to about 6 per cent, tending to be higher in young plants in long days under CO2 enrichment. The higher values are probably overestimates because of the exclusion of reflected light from the energy receipt values. © 1974 Oxford University Press.