Effects of heat treatment on germination and seed viability of four Ipomoea species

• Published in: Journal of Weed Science and Technology Vol. 69; no. 4; pp. 138 - 147
• Main Authors: Asami, Hidenori, Ishioka, Gen
• Format: Journal Article
• Language: English; Japanese
• Published: The Weed Science Society of Japan 2024
• Subjects: buried seed; heat treatment; morning glory; mulching with polyethylene sheet; seed viability
• ISSN: 0372-798X; 1882-4757
• DOI: 10.3719/weed.69.138

In Japan, the spread of morning glory (Ipomoea spp.) in soybean fields has become a serious problem, necessitating establishment of effective methods for controlling buried seeds. Therefore, in this study, we investigated interspecific differences in germination responses of four morning glory species, namely, I. coccinea (red morning glory), I. lacunosa (pitted morning glory), I. triloba (three-lobed morning glory), and I. hederacea var. integriuscula (entireleaf morning glory) related to temperature and also the effect of polyethylene sheet cover-induced soil heating on reduction of viability of buried seeds. In both laboratory and field experiments, interspecific differences were observed in temperature sensitivity related to seed survival and breaking of dormancy. I. coccinea, I. lacunosa, and I. triloba exhibited seed decay when heated to 35–40°C or higher under moist conditions (more than three days), with a decline in seed survival rates after prolonged heating. The higher the temperature and longer the period of heating, the lower the seed viability. In contrast, the effect of heating on I. hederacea var. integriuscula was lower than that on the other species. In the field, the viability of hard seeds of I. coccinea, I. lacunosa, and I. triloba was considerably reduced by mulching sheet cover-induced soil heating, indicating that the mulching cover was effective in reducing the number of seeds buried up to 5 cm below the soil surface (rate of decrease: 42–99%). Therefore, covering crops with mulching sheets in summer can effectively reduce the viability of buried seeds of I. coccinea, I. lacunosa, and I. triloba.