Estimation of genetic parameters and interrelationships between traits assessed through the genetic and phenotypic variation among the genotypes provides a way for crop/trait improvement. Twenty genotypes including checks (Hardinath-1 and Chaite-5) were evaluated for eight traits in an alpha lattice design with three replications at the National Rice Research Program, Hardinath in the spring season of 2024. The analyzed result revealed variation among the genotypes from studied traits was due to inherent nature and genetic background. The studied genotypes matured in less than 125 days. The early maturity is a crucial trait in spring season rice which facilitates following main season rice cultivation in Nepal. The high-yielding genotypes IR 17A 3012, IR 17L 1368 and Hardinath 1-10 could get notified directly as a variety or applied in breeding programs. The high GCV, PCV and ECV values were recorded in filled grains per panicle, grain yield per ha, tillers per hill, and thousand-grain weight suggesting the genotypes have diverse genetic backgrounds and could be selected for further trait enhancement in the breeding program. The highest broad sense heritability was recorded for maturity days (0.89), heading days (0.88), plant height (0.74), and thousand-grain weight (0.66) indicating a high response to selection of particular traits merely governed by genotype and less influenced by environment. High heritability coupled with high GAM was recorded for thousand-grain weight (0.66, 24.31) indicating the trait was under the control of additive gene action and that direct selection of these traits would be effective for crop improvement. Positive and strong associations between grain yield per ha with heading days and maturity days at both genotype and phenotype levels and with filled grains per panicle at the genotypic level indicate grain yield dependent on independent variables (phenological and filled grains per panicle) in spring season rice. Thus, trait selection based on variability and association helps to select potential varieties or parent lines applicable in the spring rice breeding program.