Seeding depth effects on elongation, emergence, and early development of California rice cultivars

Abstract

AbstractThe continuous use of a water‐seeded cropping system for California rice (Oryza sativa L.), along with a limited palette of available herbicides, have selected for flood‐tolerant grasses, aquatic species, and herbicide‐resistant weed populations throughout the region. Alternative cropping methods such as stale‐seedbed and deeper drill seeding may be combined to allow novel herbicide modes of action and combat resistance while providing economically competitive yields. Two experiments were conducted to evaluate rice cultivars for vigorous traits that would facilitate such a stale‐drill cropping methodology. Four cultivars of California rice were grown in glasshouses and evaluated for differences in germination, elongation, emergence, and early season morphology. Cultivars M‐205 and M‐209 were found to have greater rates of total below‐soil elongation, and greater rates of mesocotyl and coleoptile elongation overall, across depths. M‐205 and M‐209 were also found to have higher rates of emergence across depths. Differences in aboveground growth parameters of emerged seedlings were only found at 0‐, 6.4‐, and 7.6‐cm planting depths. Based on observed below‐ and above‐soil growth and development, M‐205 and M‐209 exhibited greater vigor overall, as well as high levels of emergence from depths greater than 2 cm. Therefore, these cultivars should be suitable for stale‐drill seeding as a strategy for managing herbicide resistance in California.