An experiment was conducted to create new rice varieties by crossbreeding different types of rice plants. They planted 107 different types of rice in a field and also planted 46 new hybrid plants. By measuring different traits like plant height and grain yield, they found that the number of filled grains per panicle is the most important factor for high grain yield. This means that selecting plants with more filled grains per panicle can help in producing high-yielding rice varieties.