With rapid population increase, labour scarcity, and soil nutrient depletion, agricultural lands must be used sustainably to meet the ever-increasing demands for food and livelihood. Perennial rice varieties show promise in meeting the conflicting needs for reducing input use while increasing agricultural production. But, little is known about their agronomic and economic performances and the suitable cropping system in West Africa. The objective of this study was to evaluate the effects of the cropping system and perennial rice variety on grain yield, labour productivity, and profitability in irrigated lowlands in West Africa. Experiments were conducted over two years at two sites: Mbe in Côte d′Ivoire and Ndiaye in Senegal located in the sub-humid and Sahelian climatic zones, respectively. The treatments consisted of three cropping systems [one transplanting and two ratoons per year (rice–ratoon–ratoon), one transplanting and all other ratoons (rice–ratoon continuous), and transplanting twice a year (rice–rice)], and six varieties (five perennial rice varieties: PR101, PR107, PR23, PR24, and PR25 and a local check variety, which was WITA9 and Sahel108 in Mbe and Ndiaye, respectively. There were significant effects of the cropping system and variety, and their interaction on grain yield, labour productivity, and profitability at both sites. In the rice–ratoon–ratoon system, the cumulative grain yield over two years of PR23 and PR25 at Mbe (28.8 t/ha) and PR107 at Ndiaye (22.1 t/ha) was similar to that of the local check in the rice–rice system. The average cumulative grain yield across varieties over two years was the lowest in rice–ratoon continuous system at both sites. Grain yield declined with an increased number of ratoon cropping seasons in the rice–ratoon continuous system. Crop duration and the percentage of regrowth rates (ratio of the number of panicles of the ratoon crop to the number of panicles of the main crop in percentage) were the main drivers of grain yield in the ratoon cropping seasons. At Mbe, the highest labour productivity (39.6 – 39.9 kg/day) and profit (5814 – 5844 USD/ha) were achieved with PR23 and PR25 in the rice–ratoon–ratoon system, while at Ndiaye, the highest labour productivity (24.3 kg/day) and profit (2689 USD/ha) were achieved with PR107 in the rice–ratoon–ratoon system, as they had lower labour input and production costs than those in the rice–rice system with the local check. Grain yield could not be sustained in two years of the continuous ratoon cropping system with perennial rice. The rice–ratoon–ratoon system with PR23 and PR25 at Mbe and PR107 at Ndiaye offers alternative options to the conventional rice–rice system for increasing labour productivity and profitability but may require more water due to the longer crop duration. Realizing the full potential of perennial rice requires the identification of the causes of rapid yield decline and the development of agronomic practices for enhancing grain yield under ratoon cropping systems in West Africa.

中文翻译：

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西非多年生稻品种再生稻种植系统的农艺和经济评价

随着人口快速增长、劳动力稀缺和土壤养分枯竭，必须可持续地利用农业用地，以满足不断增长的粮食和生计需求。多年生水稻品种有望满足减少投入使用和增加农业产量的相互冲突的需求。但是，人们对其农艺和经济表现以及西非适宜的种植制度知之甚少。本研究的目的是评估西非灌溉低地种植制度和多年生水稻品种对粮食产量、劳动生产率和盈利能力的影响。实验在两个地点进行了两年多：科特迪瓦的姆贝和塞内加尔的恩迪亚耶，分别位于半湿润和萨赫勒气候带。处理包括三种种植制度[每年一次移栽和两宿根（水稻-宿根-宿根），一次移栽和所有其他宿根（水稻-宿根连续），以及每年移栽两次（水稻-水稻）]，以及六种种植系统。品种（五个多年生水稻品种：PR101、PR107、PR23、PR24 和 PR25，以及一个地方对照品种，分别是 Mbe 和 Ndiaye 的 WITA9 和 Sahel108。种植制度和品种及其相互作用对在水稻-宿根-宿根系统中，Mbe 的 PR23 和 PR25（28.8 吨/公顷）和 Ndiaye 的 PR107（22.1 吨/公顷）的两年累计粮食产量。与当地水稻-水稻系统的检查结果相似，两个地点的稻-宿根连续系统中两年间的平均粮食产量均随宿麦种植季节的增加而下降。水稻-再生连续系统。作物历期和再生率（再生作物穗数与主要作物穗数的百分比）是再生季粮食产量的主要驱动因素。在 Mbe，最高的劳动生产率（39.6 – 39.9 公斤/天）和利润（5814 – 5844 美元/公顷）是通过水稻-再生元-再生元系统中的 PR23 和 PR25 实现的，而在恩迪亚耶，最高的劳动生产率（24.3 PR107在水稻-再生料-再生料系统中实现了（2689美元/公顷）和利润（2689美元/公顷），因为它们的劳动力投入和生产成本低于当地检查的水稻-水稻系统。多年生稻连作两年，粮食产量无法维持。 Mbe 的 PR23 和 PR25 以及 Ndiaye 的 PR107 的水稻-宿根-宿根系统为传统的水稻-水稻系统提供了替代方案，可提高劳动生产率和盈利能力，但由于作物生长周期较长，可能需要更多的水。要充分发挥多年生稻的潜力，需要查明产量快速下降的原因，并制定农艺措施以提高西非宿根种植系统下的粮食产量。