The effect of winter and summer CO2 enrichment on the growth and fruit yield of glasshouse cucumber

SummaryThe responses of January-sown cucumbers to a range of CO2 concentrations in winter and in summer were examined together with a non-enriched treatment. In winter the CO2 concentration in the glasshouses was ambient, 400 or 1000 vpm, and in the summer, 350, 380, 400 or 450 vpm.Winter CO2 enrichment to 1000 vpm produced large increases in growth by early March. Mean CO2 concentration in the ambient treatment during this period was 370 vpm and there were no differences between the effect of this and the 400 vpm treatment. Fruit yield by mid-April was doubled when CO2 level was maintained at 400 vpm and trebled when the level was raised to 1000 vpm. Gross monetary value was similarly increased. CO2 enrichment also increased mean fruit weight, by 10% at 400 vpm and 23% at 1000 vpm. During April the mean CO2 concentration in the non-enriched treatments averaged 262 vpm with some daily means falling below 200 vpm. With summertime CO2 enrichment fruit yields and gross monetary values improved with increasin...