RECENT ADVANCES IN DIRECT SEEDED RICE: PHYSIOLOGICAL ADAPTATION, CROP MANAGEMENT, AND GENETIC IMPROVEMENT

Abstract

Owing to insufficient water, labour shortages and accelerating climate change, direct seeded rice (DSR) has emerged as a feasible and resource-efficient alternative to conventional transplanted puddled rice (TPR) systems, conserving water and reducing methane emissions. However, the initial growth phases are frequently impeded by inadequate seedling emergence, intensive weed competition, nutritional deficiencies and exposure to variable soil moisture and aeration conditions in some DSR systems, including low nitrogen use efficiency, which can impair the establishment of a healthy crop stand and stability of its yield under DSR. Identifying and phenotyping rice germplasm for critical physiological traits is essential for developing cultivars that thrive in DSR environments. The physiological basis of genotypes adaption to DSR conditions need to be integrated with phenotyping and breeding strategies. This review synthesizes the knowledge of the physiological traits that facilitate DSR adaptation evaluates both conventional and high-throughput phenotyping (HTP) techniques — digital imaging, canopy temperature measurement, chlorophyll fluorescence analysis, and remote sensing technologies to precisely evaluate these traits in field and controlled environment and examines how quantitative trait loci (QTL) mapping, genome-wide association studies (GWAS), and marker-assisted selection (MAS), significantly facilitates the development of rice varieties suitable for DSR. The review highlights the importance of multi-trait phenotyping frameworks and multi-environment testing in accelerating genetic improvement and ensuring sustainable rice production in direct seeded agricultural systems.