To clarify the effects of rice planting methods and fertilization on root morphology, growth and development, and yield formation, and to provide a theoretical basis for rice cultivation and scientific fertilization.

A two-factor experimental design was employed to investigate the effects of planting method (direct seeding and transplanting) and fertilization (no fertilization and fertilization) on root distribution, root morphology, root vigor, and lodging resistance in rice. The hybrid rice Heliangyou 332 (HLY332) and conventional rice Huanghuazhan (HHZ) were used as experimental materials.

(1) Compared with no fertilization, fertilization significantly increased yield by 15.3% and 15.0% under direct seeding and transplanting conditions for HLY332, and by 18.6% and 22.1% for HHZ, respectively. No significant yield difference was detected between planting methods for either variety. (2) In direct-seeded rice, roots were mainly distributed in the 0-5 cm soil layer. The average root biomass proportion in the 0-5 cm layer under no-fertilizer and fertilizer treatments was 50.1% and 56.8% for HLY332, and 63.5% and 67.0% for HHZ, respectively. In contrast, transplanted rice concentrated roots in the 5-10 cm layer, with proportions of 42.9% and 41.9% for HLY332, and 53.2% and 49.1% for HHZ, respectively. Fertilization increased total root biomass by 46.9% and 45.9% under direct seeding and transplanting for HLY332, and by 64.9% and 56.9% for HHZ, compared to no fertilization. Root bleeding intensity was significantly enhanced by fertilization, with increases of 113.3% and 110.6% for HLY332, and 46.1% and 60.8% for HHZ under direct seeding and transplanting, respectively. (3) Compared with direct seeding, transplanting significantly improved bending resistance. Bending resistance was increased by 23.9% and 15.2% in HLY332 under no-fertilizer and fertilized conditions, and by 12.5% and 17.0% in HHZ, respectively. Fertilization also enhanced bending resistance, with increases of 25.5% and 16.8% for HLY332 under direct seeding and transplanting, and 23.7% and 28.6% for HHZ under transplanting, relative to no fertilization.

The distinct vertical distribution of roots in the soil profile is a key trait differentiating direct-seeded and transplanted rice. Under the conditions of this study, fertilization significantly improved root morphology and increased grain yield in both planting methods, with no significant yield difference between direct seeding and transplanting. Therefore, integrating direct seeding with scientific fertilization represents a viable approach to meet the growing demand for light and simplified cultivation in rice production.