Sterility caused by cooling treatment at the flowering stage in rice plants. III. Establishment of a method of in vitro pollen germination.

Abstract

Rice pollen grains germinated more than 80% with low variation (standard deviation less than 10%) and their pollen tubes elongated to more than 150μm within one hour with a simple medium composed of 1% agar, 20% sucrose and 20μg·ml-1 (ppm) boric acid, using a Petri dish (4.5 cm in diameter). In addition to the composition of the medium, it is important that the incubation temperature should be around 20°C and that the pollen grains should be shed directly on the medium from the anthers as soon as the flowers begin to open. Under these conditions, their pollen grains began to germinate 2 to 3 min after shedding and attained maximum growth rate within 20 min. After that time, the length of pollen tube increased at a linear rate of ca. 7.5μm·min-1 over the next 15 min.