Abstract The area of cultivated agricultural land in Cambodia is 3.7 million hectares with 76% of this planted to lowland rice and 24% planted to upland crops such as cassava, maize, soybean, sugar cane and vegetables. Cambodia's average rice paddy yield at around 3 t ha−1 is around 50% of the yield potential and losses caused by weed competition have been shown to be a significant constraint. The most important issues currently affecting weed management in Cambodia's cropping systems are (a) increased climate variability and climate change, and (b) migration of labour from the rural workforce and consequent rapid mechanisation of agriculture. As a result of climate change, the wet season in Cambodia now begins and ends approximately one month later, and the bimodal rainfall distribution has strengthened, resulting in more extreme events of drought and flood during the wet season. A decline in the availability of agricultural labour has resulted in rapid mechanisation of land preparation, broadcast seeding, herbicide use and machine harvesting of rice and these changes have had significant repercussions for weed management. The resultant challenges and opportunities for weed management are presented and discussed. The main weed management challenges are associated with rice crop intensification, transition from transplanting to direct-seeded rice, changed planting dates and tillage practices in response to climate change, over-reliance on post-emergence herbicides, excessive inversion tillage, and lack of knowledge about the safe and efficacious use of herbicides. Opportunities for improved weed management in Cambodia's cropping systems include the development of integrated weed management for double crop intensive rice systems, transition from hand broadcasting to drill-seeded rice, new seeding windows and minimum tillage, non-transgenic herbicide resistant crops and education and training of input sellers and farmers to improve safety and efficacy of herbicide use.

中文翻译：

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柬埔寨的杂草研究问题、挑战和机遇

摘要 柬埔寨耕地面积370万公顷，其中76%种植低地水稻，24%种植木薯、玉米、大豆、甘蔗和蔬菜等旱地作物。柬埔寨的平均稻田产量约为 3 t ha-1，约为产量潜力的 50%，杂草竞争造成的损失已被证明是一个重大制约因素。目前影响柬埔寨种植系统杂草管理的最重要问题是 (a) 气候变异和气候变化加剧，以及 (b) 劳动力从农村劳动力中迁移以及随之而来的农业快速机械化。由于气候变化，柬埔寨的雨季现在开始和结束大约一个月后，双峰降雨分布加强，导致在雨季发生更多极端干旱和洪水事件。可用农业劳动力的减少导致整地、播种、除草剂使用和水稻机械收割的快速机械化，这些变化对杂草管理产生了重大影响。提出并讨论了由此产生的杂草管理挑战和机遇。杂草管理的主要挑战与水稻作物集约化、从移栽到直播水稻的过渡、因气候变化而改变种植日期和耕作方法、过度依赖苗后除草剂、过度反耕和缺乏知识有关关于安全有效地使用除草剂。柬埔寨改善杂草管理的机会