To determine the viability of hot water emasculation for Acacia auriculiformis, spikes composed of about 100 flowers were soaked in hot water at varying temperatures (45-60°C) and for varying lengths of time (5 s to 7 min) prior to anthesis. The rate of squashed polyads, each of which consisted of 16 pollen grains, and the germinating rate on media, decreased with temperature and time. A mating test suggested that the rates of adhering polyads per stigma and germinating polyads per stigma were lower in the self-pollination of soaked spikes than in that of normal spikes. On the other hand, the number of matured pods was not significantly different in the mating between the spikes receiving the soaking treatment ($) and the spikes receiving no treatment (#) compared with the mating between normal spikes. Although further research is needed to determine the optimal treatment conditions, these results suggest that soaking spikes into hot water, especially at 50°C for 45 s, 54°C for 15 s, and 56°C for 10 s, is an effective emasculation technique.

Ubukata 4 (2023) Size of Chinese Fir (Cunninghamia lanceolate) Seedling with Mainstems Fed by Japanese Hare (Lepus brachyurus). J Jpn For Soc 105: 239-244 In this study, we aimed to elucidate the size of Chinese fir (Cunninghamia lanceolate) seedlings, of which mainstem is fed by the Japanese hare (Lepus brachyurus).We planted 60 seedlings of various heights (82-197 cm) in a stand in Tarumizu City, Kagoshima Prefecture, and observed the feeding of the mainstem for 1 year. We found that of the 15 dead seedlings, only 1 died after the feeding of the mainstem. Among the surviving seedlings, the mainstem of 25 seedlings was fed by hares. The probability of feeding on the mainstem decreased with the increasing size of the seedlings. Regarding the generalized linear model estimation, the probability of feeding on the mainstem was ＜10％ for seedlings with an initial height of ＞140 cm or an initial diameter of ＞15 mm at the height of 60 cm. Therefore, we predict that Chinese fir seedlings are less likely to suffer feeding damage of the mainstem after they grow to be larger than the abovementioned values.

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