Weedy rice is an emerging problem of cultivated rice in California. Infestations of weedy rice in cultivated rice result in yield loss and reduced grain quality. In this study, we aimed to evaluate growth and yield components of a widely grown cultivated rice variety in California in response to weedy rice competition. Greenhouse competition experiments in an additive design were conducted in 2017 and 2018 to determine the growth and yield components of ‘M-206’ rice and five weedy rice biotypes found in California at varying weed densities. M-206 rice initially grew at a faster relative growth rate of 0.53 cm−1 wk−1 under competitive conditions compared with 0.47 cm−1 wk−1 in the absence of weedy rice, but absolute and relative growth rates declined more rapidly under competitive conditions as plants approached maturity. At harvest, M-206 plant height was reduced 13% under competitive conditions, and M-206 tiller number was reduced 23% to 49%, depending on the weedy rice biotype it was competing with. Except for 100-grain weight, the growth traits and grain yield components of M-206 rice were reduced with increasing density of weedy rice. At the highest weed density measured, 40 plants m−2, M-206 rice had yield losses of 69% grain yield plant−1, 69% panicle weight, 59% fresh and dry biomass, 55% grain yield panicle−1, and 54% panicle number. The five evaluated weedy rice biotypes varied widely in early growth rates, height, biomass production, and grain yield, indicating differing competitive strategies. Most weedy rice biotypes produce plants with greater plant height, tiller number, panicle number, and above- and below-ground biomass compared with cultivated rice. Weedy rice biotypes produced 45% to 57% higher grain yield per plant than M-206 rice under competitive conditions.

中文翻译：

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加利福尼亚杂草稻 (Oryza sativa f. spontanea) 生物型竞争对栽培稻品种的影响

杂草水稻是加利福尼亚种植水稻的一个新问题。栽培稻中杂草稻的侵染导致产量损失和谷物质量下降。在这项研究中，我们旨在评估加利福尼亚广泛种植的水稻品种的生长和产量成分，以应对杂草水稻的竞争。2017 年和 2018 年在加法设计中进行了温室竞争实验，以确定在加利福尼亚不同杂草密度下发现的“M-206”水稻和五种杂草水稻生物型的生长和产量成分。M-206 水稻最初以 0.53 厘米的较快相对生长速度生长-1周-1在竞争条件下与 0.47 厘米相比-1周-1在没有杂草稻的情况下，随着植物接近成熟，绝对和相对增长率在竞争条件下下降得更快。收获时，在竞争条件下，M-206 株高减少了 13%，M-206 分蘖数减少了 23% 至 49%，这取决于它所竞争的杂草稻生物型。除100粒重外，M-206水稻的生长性状和产量成分均随着杂草稻密度的增加而降低。在测量的最高杂草密度下，40 株 m-2, M-206 水稻产量损失 69%-1, 69% 穗重, 59% 鲜干生物量, 55% 穗粒产量-1, 和 54% 的穗数。评估的五种杂草稻生物型在早期生长速率、高度、生物量生产和谷物产量方面差异很大，表明不同的竞争策略。与栽培稻相比，大多数杂草稻生物型产生的植物具有更大的株高、分蘖数、穗数以及地上和地下生物量。在竞争条件下，杂草稻生物型的单株谷物产量比 M-206 稻高 45% 至 57%。