Effect of Temperature on Seed Germination in Spinach (Spinacia oleracea)

Abstract

Breeding heat-tolerant spinach is an important project to meet the demand of increasing spinach production in heat conditions. Seed germination is the early stage to test, screen, and develop heat-tolerant spinach genotypes. The objective of this research was to determine temperature effect on the seed germination percentage and to select heat-tolerant spinach genotypes. A total of nine spinach genotypes were used in this research. The germination experiment was conducted using seven temperatures: 10, 15, 20, 25, 30, 32, and 35 °C under growth chambers. The temperature trials were conducted using completely randomized design (CRD) with three replicates. Spinach seed germination percentage varied among the nine spinach genotypes under the seven temperatures, indicating that genetic variation for heat tolerance existed in the nine spinach genotypes. ‘Donkey’, ‘Marabu’, and ‘Raccoon’ showed higher seed germination percentage with over 70% at 30 and 32 °C, indicating the three spinach genotypes had heat tolerance for germination. However, all spinach genotypes except ‘Ozarka II’ dropped their germination percentages sharply to less than 30%; ‘Ozarka II’ had 63% germination under 35 °C, indicating it is a good source of heat tolerance for seed germination. The higher germination percentages above 30 °C of ‘Ozarka II’, ‘Donkey’, ‘Marabu’, and ‘Raccoon’ may indicate their potential as donors of heat-tolerant traits in spinach breeding program.