Exploring Key Yield Components Influencing Grain Yield in Ultrashort- and Short-Duration Rice Cultivars

Identifying the key yield components influencing rice yield is crucial for developing high-yielding ultrashort- and short-duration cultivars, which could meet the demands of intensified cropping systems. This study used data collected over 6 years to compare grain yield and yield components between the ultrashort-duration (85–100 days) and short-duration (100–110 days) rice cultivars under mechanical transplanting conditions. Grain yield in the ultrashort-duration group ranged from 5.71 to 10.47 t ha−1 (mean: 7.97 t ha−1), while that in the short-duration group ranged from 6.00 to 11.84 t ha−1 (mean: 7.67 t ha−1), with no significant difference between the groups (p > 0.05). The ultrashort-duration group had 15.56% fewer spikelets per panicle but a 7.9% higher grain filling percentage than the short-duration group (p < 0.01). In terms of importance, grain weight was the most critical factor in the ultrashort-duration group (contributing 42.8% to yield), followed by the grain filling percentage (37.5%). Conversely, in the short-duration group, spikelets per panicle was the most important factor, contributing 43.1%, with grain weight accounting for 32.1%. In summary, the ultrashort-duration varieties should prioritize grain weight and the grain filling percentage, while the short-duration varieties should focus on spikelets per panicle and grain weight. Future research should integrate these insights into breeding programs to develop high-yielding short-duration cultivars for intensified cropping systems.