Attraction activities of terrestrial vegetables for black abalone Haliotis discus, oriental weatherfish Misgurnus anguillicaudatus, and yellowtail Seriola quinqueradiata were estimated by behavioral experi ments in a laboratory test tank as well as an attraction index a for both abalone and oriental weatherfish, and another attraction index gr for yellowtail. The indexes a and gr were estimated by a method described in previous papers. Most of the vegetables tested (39 breeds from 36 kinds of vegeta bles) showed, to some extent, attraction activities for these three animals tested. The highest activity was observed in soybean Glycine max for black abalone, cabbage Brassica oleracea var. capitata (Naka wase 2) for weatherfish, and onion Allium cepa for yellowtail. The attraction activities of these vegeta bles clearly depended on the concentrations used.

A study was conducted to improve the seedling emergence rate of lettuce (Lactuca sativa) seeds at high temperatures using a convenient postsown priming method. Seeding mixtures adjusted to 35%, 45%, or 55% moisture content were sown with lettuce ‘Patriot’ in cell trays. Postsown priming was performed at 20 °C for 1 day and at 30 °C for 3 or 5 days. After the treatment, trays were moved to an emergence room kept at 32.5 °C, a temperature assumed to be typical of non-air-conditioned rooms in nurseries. Emergence of nonprimed controls was 9% to 16% after 2 days in the emergence room and was 59% to 75% on day 6. In contrast, seedling emergences on day 2 were 95%, 76%, and 78% to 79% in 55% moisture at 20 °C for 1 day, 55% moisture at 30 °C for 3 days, and 45% to 55% moisture at 30 °C for 5 days, respectively. Therefore, the treatment with 55% moisture at 20 °C for 1 day appeared most effective; however, post-sown priming with 55% moisture at 30 °C for 3 days or 45% to 55% moisture at 30 °C for 5 days may be more practical due to lower temperature-control costs.

No abstract

Seeds of 14 lettuce cultivars for spring or summer cultivation were sown in cell trays filled with seeding mixture and kept in growth cabinets at 20, 30, or 35°C for six days to study emergence inhibition at high temperatures. All cultivars commenced emergence on day three after sowing at 20°C, on day two at 30°C, and on days two to five at 35°C. Emergence rates on the day of emergence (at 35°C, on the day when many cultivars began to emerge) and the day after, and the final emergence rate were 52-97%, 77-98%, and 81-100%, respectively, at 20°C; 7-66%, 25-87%, and 61-98%, respectively, at 30°C; and 0-43%, 0-50%, and 1-63%, respectively, at 35°C. All cultivars showed emergence inhibition at 30°C or higher but the degree of inhibition varied greatly between them. The upper temperature limit for emergence, T 50 , depended greatly on the cultivar, ranging from 31°C for 'Olympia' to higher than 35°C for 'Château', 'King Cisco', and 'Sacramento'. Comparison of the present results with those of previous reports suggests that breeding efforts over recent decades have generally improved the performance of lettuce emergence at increased temperatures.