In South Asia's rice-based cropping systems, most farmers flood and repetitively till their fields before transplanting. This establishment method, commonly termed puddled transplanted rice (TPR), is costly. In addition, it is labor and energy intensive. To increase labor and energy efficiency in rice production, reduced or zero-tilled direct seeded rice (ZT-DSR) is commonly proposed as an alternative tillage and crop establishment (TCE) option. Effective management of weeds in ZT-DSR however remains a major challenge. We conducted a four-year experiment under a rice-maize rotation in Northwestern Bangladesh in the eastern Gangetic Plains to examine the performance of two TCE methods and three weed management regimes (WMR) on the diversity and competitiveness of weed communities in the rice phase of the rotation. The Shannon-Weiner Diversity Index, a measure of species diversity, was significantly greater under ZT-DSR than puddled TPR. It was also greater under no weed control (Weedy) and two manual weeding (MW) treatments compared to chemical herbicide with manual weeding (C + MW). In DSR Weedy plots, weed communities began shifting from grasses to sedges from the rotation's second year, while in the ZT-DSR and C + MW treatments, sedges were consistently predominant. In both puddled TPR Weedy and TPR C + MW treatments, broadleaves and grasses were dominant in the initial year, while sedges dominated in the final year. There were significant main effects of year (Y) and weed management regime (WMR), but not of TCE. Significant Y × TCE and TCE × WMR interaction effects on rice yield were also observed. Grain yields under ZT-DSR were similar to puddled TPR. ZT-DSR with one application of pre-emergence herbicide followed by one hand weeding at 28 days after establishment however resulted in significantly higher grain yield (5.34 t ha−1) compared the other weed management regimes. Future research should address methods to effectively manage weed community composition shifts in both ZT-DSR and TPR under rice-maize rotations utilizing integrated and low-cost strategies that can be readily applied by farmers in the eastern Gangetic Plains.

中文翻译：

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受耕作、作物种植和杂草控制影响的多年杂草群落动态和水稻产量：对恒河平原东部水稻-玉米轮作的影响

在南亚以稻米为基础的种植系统中，大多数农民在移栽前会在田间浇水并反复耕种。这种建立方法，通常称为水坑移栽水稻 (TPR)，成本高昂。此外，它是劳动和能源密集型的。为了提高水稻生产的劳动力和能源效率，通常建议将减耕或零耕直播水稻 (ZT-DSR) 作为替代耕作和作物种植 (TCE) 选项。然而，有效管理 ZT-DSR 中的杂草仍然是一个重大挑战。我们在恒河平原东部的孟加拉国西北部进行了一项为期四年的水稻 - 玉米轮作试验，以检查两种 TCE 方法和三种杂草管理制度 (WMR) 对水稻阶段杂草群落多样性和竞争力的影响。旋转。Shannon-Weiner 多样性指数是物种多样性的衡量标准，在 ZT-DSR 下显着高于混合 TPR。与人工除草 (C + MW) 的化学除草剂相比，无杂草控制 (Weedy) 和两种人工除草 (MW) 处理的效果也更大。在 DSR 杂草地块中，杂草群落从轮作的第二年开始从草转向莎草，而在 ZT-DSR 和 C + MW 处理中，莎草一直占主导地位。在混水 TPR Weedy 和 TPR C + MW 处理中，阔叶和禾本科植物在最初一年占主导地位，而莎草在最后一年占主导地位。年份 (Y) 和杂草管理制度 (WMR) 的主效应显着，而 TCE 的主效应不显着。还观察到显着的 Y × TCE 和 TCE × WMR 相互作用对水​​稻产量的影响。ZT-DSR 下的谷物产量与浸渍 TPR 相似。然而，与其他杂草管理方案相比，ZT-DSR 与一种芽前除草剂施用，然后在建立后 28 天进行一只手除草，导致谷物产量显着提高（5.34 t ha-1）。未来的研究应该利用综合和低成本的策略来有效管理 ZT-DSR 和 TPR 下水稻 - 玉米轮作下杂草群落组成变化的方法，这些策略可以由恒河平原东部的农民轻松应用。