**4. Materials and Methods**

#### *4.1. Rice Material Collection and Phenotyping*

The plant material of this experiment included 204 rice germplasms, which included lines with a wide range of grain size related traits. Plant material was received from the Key Laboratory of Crop Genetics and Breeding section, Yangzhou University, Jiangsu province, P.R. China, comprising rice lines with higher yields. The field experiment was carried out in the experimental fields of the research capacity in Yangzhou University (E, N) during the normal rice season (from May to November) in 2018. Sowing of the material was carried out in the nursery for the grain cell, and then the 30 day old nursery was transplanted into well prepared fields following standard agronomic practices in order to assure full expression of the traits. Plant to Plant distance was maintained at 10 cm, whereas row to row distance was maintained at 15 cm. For grain trait phenotyping, data were collected during the stage of plant maturity from the middle plants in the central row of each entry. Grain size related traits (i.e., grain length (GL), grain width (GW), and grain thickness (GT)) were measured in (millimeters) as the average from ten completely mature and filled grains using digital Vernier calipers. Likewise, data for grain weight related traits (i.e., thousand grain weight (TGW)) were measured for 250 carefully counted, filled, and fully mature rice grains using an electronic digital weighing balance, and the values were multiplied by a factor of 4 to obtain the 1000 grain weight.
