Evaluation of Seed Germination, Growth, Flowering and Anthocyanin Content of Edible Flowers under Greenhouse System in Southern Thailand

Abstract

The flowering plant’s field production in the Southern area is limited by the weather condition, which has a lot of rain and high humidity. However, the trend to use the flower as edible flowers is increasing continuously. Therefore, this study evaluated the seed germination flowering and anthocyanin content of eight edible flowers grown as potted plants. Eight species of edible flowers were Impatiens (Impatiens wallerana), two of Dianthus (Dianthus chinensis), ‘Diamond Series’ and ‘Diana Series’, Pansy (Viola wittrockiana), Antirrhinum (Antirrhinum majus), Celosia (Celosia plumosa), Torenia (Torenia fournieri) and Cosmos (Cosmos sulphureus). Seeds were sown under a greenhouse at the average temperature of 28.7 ± 0.7 ๐C and 79.0 ± 4.8%RH. These edible flower seeds could be divided into three groups as follows: 1) Pansy (low, 61-80%), 2) Antirrhinum and Impatiens (moderate, 81-90%), and 3) Torenia, ‘Diamond Series’ Dianthus, ‘Diana Series’ Dianthus, Celosia, and Cosmos (high, >90%). The results showed the correlation between seed germination and the greenhouse environment, i.e., temperature (especially average temperature), humidity, light intensity and daylength. Regarding vegetative growth. Cosmos has the highest relative growth rate by measuring plant height was found with in first week after transplant, with was 0.349 ± 0.0022 cm/cm/day in Cosmos. Based on time after transplanting, the RGR divide the two group of edible flowers. There was a high RGR at the first and low RGR in the latter periods, i.e., Cosmos, Torenia, Celosia, Dianthus ‘Diamond Series’ and ‘Diana Series’, and Impatiens. In contrast, the second group had ) low RGR in the first period and a high RGR in latter period, i.e., Antirrhinum and Pansy. While the results are based on the days of flower bud break and blooming, it could be divided into four groups as follows: 1) Celosia and Cosmos (≤40 days), 2) Antirrhinum, Impatiens and Torenia (>40-50 days), 3) ‘Diana Series’ and ‘Diamond Series’ Dianthus (>50-60 days), and 4) Pansy (>60 days). It was found that daylength and the maximum temperature was the main factor that effects faster flowering. Torenia, Pansy, and ‘Diamond Series’ Dianthus are part of anthocyanin content, showing the greatest while Cosmos, Antirrhinum, and Impatiens gave the lowest anthocyanin content.