*4.1. Plant Materials*

The parental line Sasanishiki is typical *japonica* varieties, and the parental line Habataki is an admixture variety with both *indica* and *japonica* pedigree. Sasanishiki was crossed to Habataki, and the F1 plant was crossed to Sasanishiki, and then inbred over 10 generations by single-seed descent to generate a population containing 85 BILs. The BILs were then backcrossed to the maternal parent Sasanishiki to obtain 85 BILF1s. All materials are maintained at the Rice Research Institute of Shenyang Agricultural University (Shenyang, China). All plants were planted in random block design under standard agricultural management practice in the paddy field of Shenyang Agricultural University (N41◦, E123◦). All lines were planted with three biological replicates A total of 300 plants in a 16 m<sup>2</sup>

plot were characterized for each line. Plant height, panicle number, grain number per panicle, setting rate, and 1000-grain weight were surveyed in the field in 2018. Both BILs and BILF1s were used in QTL analysis.
