The effects of summer CO2 enrichment and ventilation temperatures on the yield, quality and value of glasshouse tomatoes

SummaryThe responses of January-sown tomatoes to a range of CO2 concentrations (ambient, 375, 450 and 525 vpm) in summer were investigated in two experiments. The first was designed to examine the effects of summer CO2 on the fruit yield of four cultivars planted in two rooting substrates (soil or peat-bags). The aim of the second was to increase the cost-effectiveness of the treatment by delaying greenhouse ventilation in order that reductions in the inputs of CO2 might be achieved at levels of enrichment above ambient. Summer CO2 enrichment was applied for eighteen weeks starting at the end of April. Fruiting response was linearly related to summer CO2 concentration. The yield response slopes for plants grown in different rooting substrates, ventilation temperatures and seasons were not significantly different. The overall response increment showed that in the range 320 to 526 vpm (the mean measured values), marketable fruit yield increased by 2.65 ± 0.201 kg m-2 for each 100 vpm increase in mean CO2 le...