Influence of environmental factors in the development of root systems in young seedlings of rice (Oryza sativa L.) and barnyardgrass (Echinochloa crus-galli (L.) Beauv. var. crus-galli)

• Published in: Journal of Weed Science and Technology Vol. 43; no. 4; pp. 328 - 333
• Main Authors: Ogasawara, M. (Utsunomiya Univ. (Japan)), Nozaki, T, Takeuchi, Y, Konnai, M
• Format: Journal Article
• Language: Japanese
• Published: The Weed Science Society of Japan 1998
• Subjects: barnyardgrass; direct seeded rice; ECHINOCHLOA CRUS GALLI; fractal dimension of root system; ORYZA SATIVA; PLANTULAS; PLANTULE; root growth angle; root morphology; ROOT SYSTEMS; SEEDLINGS; SISTEMA RADICULAR; SYSTEME RACINAIRE
• ISSN: 0372-798X; 1882-4757
• DOI: 10.3719/weed.43.328

Morphological characteristics of root systems in direct-seeded rice (Oryza sativa L., cv. Hoshinohikari) and barnyardgrass (Echinochloa crus-galli (L.) Beauv. var. crus-galli) grown in root boxes under different conditions including variations in soil water content, sowing depth and soil temperature were analyzed in terms of total root length, number of crown roots, fractal dimension of root system and root growth angle. The results obtained are summarized as follows. (1) Under both upland and flooded conditions, the values of total root length, total crown root length, number of crown roots and fractal dimension of root system in barnyardgrass exceeded those of direct-seeded rice at 21 days after seeding. Difference in root morphology between the two plant species was more pronounced for the total root length and fractal dimension than for the number of crown roots (Table 1). The root growth angle of barnyardgrass was about 2° smaller than that of rice under both soil water conditions (Table 2). (2) Maximum total root length was observed for rice and barnyardgrass germinated at 1cm and 0.5cm depths in soil, respectively. A significant difference in the total root length between the two plant species was observed at 1cm germination depth (Table 3). (3) The values of total root length and fractal dimension of the root system in barnyardgrass exceeded those of rice grown at a 0.5cm water depth but not a 8cm water depth (Table 4). (4) Although direct-seeded rice markedly extended roots at 24°C and root growth was severely restricted at 15°C, barnyardgrass extended roots even at 15°C and the root length was about 18 times as long as that of rice (Table 5, Fig. 1). These results suggest that the optimal growth conditions for barnyardgrass and direct-seeded rice roots are different, and when direct seeded rice and barnyardgrass are germinated at the same time, competition for space, water and nutrients in the underground zone between both plants becomes serious under the growth conditions mentioned above.