Abstract One-hundred farmers from lowland rice systems of Battambang province in Cambodia were surveyed in 2017 using a structured questionnaire with the objectives to (1) determine farmers' current knowledge and weed management practices and document the effect of adopted agronomic practices on management of weeds in rice, and (2) quantify the extent of weed seed contamination in farmers’ own saved paddy seed lots. To estimate the level of contamination by weed seeds, a one kg paddy seed sample was collected from each surveyed farmer. All farmers practiced broadcast direct-seeded rice (DSR), with an average seeding rate of 181 kg ha−1. For sowing the rice crop, 82% of farmers used their own saved seeds or bought seed from their neighbour. All the paddy seed samples were contaminated with seeds of 34 weed species with an average of 1,070 weed seeds kg−1 of paddy seed. The most common weed contaminants in the seed samples were Oryza sativa f. spontanea (weedy rice), Fimbristylis miliacea, Echinochloa colona, Echinochloa crus-galli, and Ischaemum rugosum. Weeds, in their rice field, were considered a major problem by 93% of farmers with 70% of farmers indicating a yield loss of >20% due to weed competition. All farmers followed a post-emergence based herbicide program for weed control with no use of pre-emergence herbicides. Farmers (75%) relied on the advice of input dealers on the selection and use of herbicides. Knowledge gaps were found among farmers on herbicide application techniques including selection of the right sprayer, nozzle tips, and sprayer calibration. Although 94% of farmers responded that they were aware of pesticide exposure risk, use of boots and gloves, as personal protective equipment, during spraying was low (10 and 54%, respectively). The fertilizer use was lower than recommended rates (50% of recommended N and around 40% of recommended P and K). An exploitable rice yield gap of 1.3 t ha−1 (40%) and 1.1 t ha−1 (30%) was found in the wet and dry season, respectively. These results suggest that integrated weed management (IWM) and optimum fertilizer use can play an important role in closing the rice yield gap in Battambang. IWM options using clean/certified seeds free from weed seeds, optimum fertilizer, selection and application of appropriate pre- and post-emergence herbicides at the right time, amount, and accurate application techniques can improve weed control and hence enhance the rice yield in Cambodia. Farmer training is needed to close their knowledge gaps and to educate them on IWM, especially, to manage difficult-to-control weeds such as weedy rice.

中文翻译：

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柬埔寨西北部小规模稻农的杂草管理实践

摘要 2017 年，使用结构化问卷调查了来自柬埔寨马德望省低地水稻系统的 100 名农民，其目的是 (1) 确定农民当前的知识和杂草管理实践，并记录所采用的农艺实践对杂草管理的影响。在水稻中，以及 (2) 量化农民自己保存的水稻种子批次中杂草种子污染的程度。为了估计杂草种子的污染水平，从每个接受调查的农民身上收集了 1 公斤的水稻种子样本。所有农民均采用直播直播稻 (DSR)，平均播种量为 181 kg ha−1。为了播种水稻，82% 的农民使用自己保存的种子或从邻居那里购买种子。所有水稻种子样品均被 34 种杂草的种子污染，平均为 1, 070 杂草种子 kg−1 水稻种子。种子样品中最常见的杂草污染物是 Oryza sativa f。spontanea（杂草稻）、Fimbristylis miliacea、Echinochloa colona、Echinochloa crus-galli 和 Ischaemum rugosum。93% 的农民认为稻田中的杂草是一个主要问题，70% 的农民表示由于杂草竞争，产量损失超过 20%。所有农民都遵循芽后除草剂计划来控制杂草，不使用芽前除草剂。农民 (75%) 在选择和使用除草剂方面依赖投入品经销商的建议。发现农民在除草剂应用技术方面存在知识差距，包括选择正确的喷雾器、喷嘴尖端和喷雾器校准。尽管 94% 的农民回答说他们知道农药暴露风险，使用靴子和手套，作为个人防护装备，喷洒期间的比例较低（分别为 10% 和 54%）。化肥用量低于推荐用量（推荐 N 的 50% 和推荐 P 和 K 的 40% 左右）。在雨季和旱季发现可利用的水稻产量差距分别为 1.3 t ha-1 (40%) 和 1.1 t ha-1 (30%)。这些结果表明，综合杂草管理 (IWM) 和最佳肥料使用可以在缩小马德望的水稻产量差距方面发挥重要作用。IWM 选择使用不含杂草种子的清洁/认证种子、最佳肥料、在正确的时间、数量和准确的施用技术选择和施用适当的芽前和芽后除草剂可以改善杂草控制，从而提高柬埔寨的水稻产量. 需要对农民进行培训以缩小他们的知识差距并对他们进行 IWM 教育，