Effects of different temperatures on seed germination of garden ornamentals in Allium

Abstract

This study was carried out to ascertain the effects of different temperature on seed germination of 21 species of garden ornamentals in Allium. The results are summarized as follows:
1. Weight of 100 seeds varied depending on the species, from 69 to 856mg (Table 1). However, there was no relation between the weight of seed and percentage of germination.
2. Percentage of germination of seed in ornamental Alliums was observed at 5°, 13° and 20°C. Based on the results showed in Table 2, it seemed that the optimum temperature for seed germination varied in the species.
3. From the results obtained above, species of Allium are classified into the following four types:
a. Germination occurs under warm conditions (20°C)
b. Germination occurs under cool conditions (5-13°C)
c. Germination occurs under cold conditions(2-7°C)
d. Germination occurs at wide range of temperature (5-25°C)
4. The genus Allium, containing 500 or more species, is divided into six sections taxonomically. Based on the results observed, it is likely that section I corresponds to b type and section III corresponds to a type and section V to b or c type respectively. The species belonging to d type have had long history as vegetables.
5. It seems that the optimum temperature for seed germination is closely related with the climate of native land of the species, i.e. the species distributed in Mediterranean, steppe and continental climate zone corresponds to cool, cold and warm germinating type respectively.
6. Since most of garden ornamentals of Allium have not been bred until today, it seems that they continue to have character adapted to climatic conditions of their native land.