Germination and emergence of lettuce at elevated temperatures

Abstract

Lettuce seeds have high sensitivity to the environmental conditions in which they are germinated, especially at elevated temperatures. The aim of this study was to evaluate the germination performance and emergence of seven lettuce cultivars at a high temperature, these were evaluated in growth chamber and nursery. In growth chamber was conducted in a completely randomized design (CRD) with a full 7× 6 factorial (cultivars: Red Salad Bowl, Salad Bowl Green, Marianne, Elba, Mimosa Green Salad Bowl, Crespa Lollo Bionda and Crespa para Verão; daytime temperature: 15, 20, 25, 30, 35 and 40°C) with four replicates. In nursery was also conducted in a CRD with four replicates of 50 seeds each. In both experiments, the cultivars Red Salad Bowl, Salad Bowl Green and Crespa Lollo Bionda  presented the higher levels of germination and emergence. For germination, these cultivars showed results greater than 81% at temperatures of 25, 30 and 35°C. For emergence, Red Salad Bowl and Salad Bowl Green had an average of 70%, and Crespa Lollo Bionda had 50%, higher than the other cultivars, which had values below 22%.  'Red Salad Bowl', 'Green Salad Bowl' and 'Crespa Lollo Bionda' had high germination and emergence of seeds at high temperatures.