Adoption of conservation agriculture (CA) practices can lead to the dominance of perennial weeds including purple nutsedge (Cyperus rotundus L.) in different agroecologies over time. Without effective management of this weed, successful adoption of CA in smallholder farming systems is rather unlikely. Therefore, we aimed to develop an integrated strategy for managing C. rotundus in CA-based crop rotations. This study encompassed a two-year (during 2020–21 and 2021–22) field experimentation at Kanpur, India with a split-plot design with three replications. The treatments included purple nutsedge management practices in main plot and crop rotations in sub-plot under CA platform (no-tilled with added crop residues). Six management options were adopted in the summer season (during April to June) as main plots that were super-imposed with two crop rotations such as pigeonpea (Cajanus cajan (L.) Huth) – wheat (Triticum aestivum L.) and pearlmillet (Pennisetum glaucum (L.) R.Br) – chickpea (Cicer arietinum L.) as sub-plot. Growing of cover crop Sesbania (Sesbania aculeata (Willd.) Pers.) during the summer season for 45 days followed by knockdown with 2,4-D 500 g a.i. Ha−1 (cultural management; Sesbania+2,4-D) and/or summer irrigation followed by application of halosulfuron-methyl 70 g a.i. Ha−1 at 20 days after irrigation (chemical management; halosulfuron-methyl) reduced the C. rotundus density by 37–42% and 23–64% over years, respectively, than conventional practice (ploughing during summer followed by irrigation and glyphosate 1.5 kg a.e. Ha−1 application). Besides, these practices could decrease 25–27% total weed density (p < 0.05) than conventional practice (mean of years) in summer season. Importantly, these management practices had a carry-over effect on reduction in density of C. rotundus and total weeds of rainy and winter season crops. For instance, Sesbania +2,4-D and halosulfuron-methyl decreased 35% and 15% density of C. rotundus, respectively, during rainy season than conventional practice. Irrespective of crop rotations, Sesbania +2,4-D and halosulfuron-methyl decreased 30–40% density of C. rotundus (mean of years) in winter season than conventional practice (p < 0.05). A significant reduction in dry weight of C. rotundus was recorded under Sesbania +2,4-D and halosulfuron-methyl in summer season by 13–23%, rainy season by 23–29%, and winter season by 55–72% than conventional practice. Pearlmillet-chickpea rotation had a 10–35% lower infestation of C. rotundus than pigeonpea-wheat (p < 0.05). Management practices such as Sesbania +2,4-D and halosulfuron-methyl had higher system productivity by 15–19% in 2020–21 (p < 0.05), 5–7% in 2021–22 (p > 0.05), and 10–12% in average (p > 0.05) than conventional practice. Summer mungbean cultivation increased 45.2% and 10.1% density of C. rotundus in rainy season over Sesbania +2,4-D and halosulfuron-methyl in CA system, respectively (p < 0.05). Furthermore, the density of this weed was significantly higher under pigeonpea crop during rainy season by 41.4% than under pearlmillet crop (mean of years). Therefore, system-based approaches such as growing of cover crop Sesbania followed by knockdown with 2,4-D (Sesbania +2,4-D) and/or herbicide-based management through halosulfuron-methyl during summer season and subsequently recommended weed management practices in cropping systems (pearlmillet – chickpea and pigeonpea – wheat) can reduce the infestation of C. rotundus and total weeds in CA than conventional practice.

中文翻译：

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覆盖作物和除草剂可以控制紫色坚果 （Cyperus rotundus L.） 并在以保护性农业为基础的作物轮作中提高作物产量


随着时间的推移，采用保护性农业 （CA） 做法会导致多年生杂草（包括紫坚果 （Cyperus rotundus L.））在不同的农业生态学中占据主导地位。如果不对这种杂草进行有效管理，在小农农业系统中成功采用 CA 的可能性相当小。因此，我们的目标是制定一种综合策略，在基于 CA 的作物轮作中管理 C. rotundus。这项研究包括在印度坎普尔进行的为期两年（2020-21 年和 2021-22 年）的田间实验，采用具有三个重复的裂区设计。处理包括主地块中的紫色坚果管理实践和 CA 平台下子地块的作物轮作（添加作物残留物的免耕）。夏季（4 月至 6 月）采用六种管理方案作为主要地块，与两种作物轮作叠加，如木豆 （Cajanus cajan （L.） Huth） – 小麦 （Triticum aestivum L.） 和珍珠小米 （Pennisetum glaucum （L.） R.Br） – 鹰嘴豆 （Cicer arietinum L.） 作为子地块。在夏季种植覆盖作物 Sesbania （Sesbania aculeata （Willd.） Pers.） 45 天，然后用 2,4-D 500 g a.i.Ha−1 （文化管理;Sesbania+2,4-D） 和/或夏季冲洗，然后施用甲基卤磺隆 70 g a.i.灌溉后 20 天的 Ha-1（化学管理;甲基卤嘧磺隆）比传统做法（夏季犁地，然后灌溉和草甘膦 1.5 公斤，即 Ha-1 施用）在几年内将 C. rotundus 密度分别降低了 37-42% 和 23-64%。此外，在夏季，这些做法可以比传统做法（平均年数）降低 25-27% 的总杂草密度 （p < 0.05）。 重要的是，这些管理措施对 C. rotundus 密度的降低和雨季和冬季作物的总杂草量产生了残留效应。例如，与传统做法相比，Sesbania +2,4-D 和氟嘧磺隆-甲基在雨季的密度分别降低了 35% 和 15%。无论作物轮作如何，Sesbania +2,4-D 和氟嘧磺隆-甲基在冬季比传统做法降低了 30-40% 的 C. rotundus 密度（平均年数）（p < 0.05）。与传统做法相比，在 Sesbania +2,4-D 和氟嘧磺隆-甲基下，夏季和冬季的 C. rotundus 干重显着降低了 13-23%，雨季降低了 23-29%，冬季降低了 55-72%。珍珠粟-鹰嘴豆轮作对 C. rotundus 的侵染率比木豆-小麦低 10-35%（p < 0.05）。与传统做法相比，Sesbania +2,4-D 和甲基卤嘧磺隆等管理实践在 2020-21 年的系统生产率提高了 15-19%（p < 0.05），2021-22 年提高了 5-7%（p > 0.05），平均提高了 10-12%（p > 0.05）。夏季绿豆种植在雨季比塞斯巴尼亚 +2,4-D 和 CA 系统中的 C. rotundus 密度分别增加了 45.2% 和 10.1% （p < 0.05）。此外，雨季木豆作物的杂草密度显著高于珍珠粟作物 41.4%（平均年）。因此，基于系统的方法，例如种植覆盖作物 Sesbania，然后用 2,4-D （Sesbania +2,4-D） 敲除和/或在夏季通过甲基卤嘧磺隆进行基于除草剂的管理，以及随后在种植系统中推荐的杂草管理做法（珍珠小米 - 鹰嘴豆和木豆 - 小麦）可以减少碳的侵扰。 CA 的 rotundus 和 total weeds 比传统做法。