Effects of the sucrose concentrations and incubation periods on in vitro pollen germination and pollen tube growth in three rice cultivars

High-quality pollen grains are essential for artificial cross pollination and grain production. The optimization of culture conditions for in vitro pollen germination is useful for evaluating pollen quality. However, there is limited information on in vitro pollen germination system for rice (<i>Oryza sativa</i> L.). Therefore, this study aimed to develop an efficient pollen germination system for rice and determine the optimal incubation period, incubation temperature, and sucrose concentration. Three rice cultivars were studied: 'Nanatsuboshi', 'Nipponbare', and 'Kitaake' and culture media developed in the previous study were used to optimize the conditions. The highest pollen germination rates for all cultivars were observed in the medium containing 20% (w/v) sucrose. Pollen tube bursting was observed during pollen tube elongation. We discussed the relationship between the incubation period and pollen tube bursting. This study contributes to evaluating rice pollen germination, pollen tube growth, and pollen tube bursting to support grain production.