The researchers aimed to improve rice varieties by studying the combining ability and heterosis of different parent lines. They used a specific breeding design to create hybrids and compared their performance with their parent plants. They found that certain parent lines showed good potential for grain yield and other traits, while specific hybrid combinations, like HPR 2755 × Kasturi, exhibited the best results for grain yield per plant. This hybrid showed desirable traits, significant effects, and high yield compared to standard varieties.