Effects of Day and Night Temperatures and Carbon Dioxide Enrichment on Yield of Glasshouse Tomatoes

Abstract

SummaryDay temperatures above 64 °F (17.8 °C) and night temperatutes above 60 °F (15.6 °C) increased early yield but not total yield of November-sown tomatoes. Gross monetary returns for the whole crop increased with temperature only when C02 enrichment was given. Higher day temperatures in stage 1 (pricking-out to appearance of immature flower buds) were more beneficial than higher night temperatures, although the opposite was probably true in stage 3 (first anthesis to one month after first fruit harvest). High temperature in stage 2) and low f temperature in stage"(flower bud appearance to first anthesis) enhanced flower and fruit development in the lower trusses, but high temperature in stage 3 reduced the number of fruits in most trusses. C02 enrichment increased the early crop by 90% and the total crop by 30%. Monetary returns for the whole crop increased by 37 %. The gain from enrichment was mainly due to increases in fruit number and size. Enrichment advanced the date of flowering of the first truss, but no furthur advancement was recorded for subsequent trusses.The proportion of fruit marketed as ‘select’ grade tended to increase with temperature, but CO2 enrichment significantly reduced the proportion, probably as a consequence of a shift to larger-sized fruits.