Test Materials and Test Methods
Two japonica rice varieties with significant difference in grain amylose content were selected, i.e., parent Xixuan 1 (18.48%), Tong 769 (15.81%), and transgressive offspring stable strains Dongnong 1101 (19.71%) and Dongnong 1124 (7.40%). In 2015–2016, the pot experiment was carried out in the Agricultural College of Northeast Agricultural University. The length of the pot was 100 cm, the width was 40 cm, and the height was 60 cm. From April 1 to 15, according to the growth period of the test materials, sowing was carried out in stages to ensure the heading stage was as consistent as possible. Furthermore, plug-seedlings in trays in a greenhouse, equidistantly dibble sowing of a single sprouting seed, and dry rice-nursery management were selected. On May 15, rice seedlings with consistent growth potential were selected for transplantation. Each variety was inserted in three pots and 24 seedlings were equidistantly planted in every pot. After seedling survival, 12 seedlings were planted and treated with normal fertilizer.
At heading stage, the rice ears of the same size and extension at the same time were selected and marked with a sign. On the 10th, 20th, and 30th day after heading, eight rice ears with signs were selected, respectively. Then, 20 grains in the middle of the ear, with the same grain filling, were selected. With shells and embryos removed at a low temperature, they were put into a sterile tube, which was then quickly placed into liquid nitrogen. Finally, they were stored at -80ºC to be used for quantitative analysis of fluorescence.