Some effects of air and root temperatures on the yield and quality of glasshouse tomatoes

Abstract

SummaryNovember-sown tomato crops in NFT were grown at 11–16°C night air temperatures to investigate the possibility of using lower temperatures in order to save fuel. Fruiting was delayed at the lower air temperatures but the final yield and total crop values were increased, provided the lower temperature was restricted either to the period up to or following the onset of fruit picking. The former was preferable because more fuel was saved. The time intervals between the flowering of successive inflorescences and the time between flowering and fruit ripening within an inflorescence depended on air temperature, both processes having a temperature coefficient (Q10) of 1.7. The effect of low air temperature regimes on these two components of crop production is therefore predictable. Root temperatures were increased by up to 12°C above the ambient of ≃ 15°C, either from flowering to picking or from picking onwards in various combinations with the air temperatures. Increasing root temperature up to picking resulted in small reductions in yield and quality of early fruit. During the fruiting phase, however, root heating increased final yield by about 10% over 20 weeks of picking. The economic data suggest that lower night air temperatures than those currently used and higher root temperatures, related to growth phase, would increase the profitability of the tomato crop.