Influence of temperatureon yield and earliness of lettuce grownin the winter period

Abstract

Lettuce as a vegetable species has moderate demands in terms of growing conditions. Therefore, the aim of this study was to determine the influence of immediate covering of plants by agrotextile using the sum of the temperature on earliness and yield of lettuce grown in a greenhouse without heating. The experiment was conducted on four varieties (Devonia, Nizzi, Boreale and Robinson) that have different resistance to low temperatures. The lowest average temperature during the growing cycle period in the greenhouse was 4.0°C while maximum temperature was 13.5°C. At the same time, the average minimum temperature under agrotextile was 6.1°C while maximum temperature was 19.0°C. In the open field, these temperatures were 0.2°C and 9.2°C. This confirms the fact that by using agrotextile in a greenhouse in the winter period temperature can increase by up to 10°C in comparison to the open field. Based on the sum of active temperatures, it was found that Devonia is the earliest variety and it needs the sum of temperatures of 764°C to reach technological maturity. The Robinson variety has the longest vegetation which requires the sum of temperatures of 890°C until the harvest period. Furthermore, Robinson had the biggest head (411.5 g) and achieved the highest yield per area unit (8.22 kg m-2). The lowest yield (4.95 kg m-2) was obtained in the Nizzi variety, which had the smallest head (249.5 g).

Keywords

• lettuce
• temperature
• earliness
• yields