Effect of different day and night temperature regimes on greenhouse cucumber young plant production, flower bud formation and early yield

Abstract

The effects of different day temperature (DT) and night temperature (NT) combinations on the growth and development of young cucumber plants during propagation were investigated. The temperature combinations gave differences (DIF) between DT and NT ranging from −12 to +12°C. After propagation the plants were transferred to a greenhouse and grown at a constant DT and NT set point of 21°C for 8 weeks after propagation. The experiment was carried out in early spring under natural light conditions. The rate of development was dependent on the temperature regime. DT lower than NT inhibited growth and development of the young plants, except for leaf unfolding rate which depended on the average daily temperature (ADT) only. Both an increase in ADT and DIF enhanced internode length. However, increasing the ADT by only raising DT affected the elongation to a larger extent than an equal raise of DT and NT. For flower bud development an increase in negative values of DIF reduced the number of flower buds to a greater extent than an increase in positive values. The optimum propagation temperature, based on earliness (first harvest) and early yield was approximately 25°C. Raising the ADT from 15 to 25°C reduced the time to first harvest by 1.6 days per 1°C and increased the average total yield during the first 8 weeks after transplanting by 0.54 kg m −2 °C −1. DIF had no effect on earliness nor the yield, but improved fruit quality.