Parthenium weed is an invasive species in a growing number of countries where it infests numerous crop fields, including sorghum. Two field studies were conducted to quantify the effect of parthenium weed on the performance of grain sorghum at different weed densities (0, 5, 10, 15 and 20 plants m−2) and durations of weed-crop competition (season-long weed-free, weed-free after 2, 4, 6 or 8 weeks, and season-long weedy). Our aim was to identify the density threshold and ideal duration to control parthenium weed in sorghum fields. Both field experiments were planned in a randomised complete block design each with three replications in 2016 and were repeated in 2017. Parthenium weed biomass increased significantly with increasing density and competition duration. The increasing parthenium weed density had a linear negative effect on sorghum growth, yield and yield-contributing traits. The highest yield loss, of up to 66%, was recorded at the highest parthenium weed density of 20 plants m−2 when compared to weed-free treatment. In addition, the season-long competition of this weed with sorghum caused 81% reduction in grain yield over weed-free treatment. According to our results, parthenium weed should be managed below a density of 5 plants m−2 and throughout the crop growth duration in grain sorghum fields as it can cause serious yield losses even at low densities and through strong competition at early as well as late growth stages of the crop.

中文翻译：

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干旱条件下Parthenium杂草（Parthenium hysterophorus）与高粱竞争

Parthenium 杂草在越来越多的国家是一种入侵物种，它侵染了包括高粱在内的许多农田。进行了两项田间研究，以量化部分杂草对不同杂草密度（0、5、10、15 和 20 株 m-2) 和杂草作物竞争的持续时间（长季节无杂草，2、4、6 或 8 周后无杂草，以及长季节杂草）。我们的目的是确定控制高粱田中部分杂草的密度阈值和理想持续时间。两项田间试验均计划在 2016 年以随机完整区组设计进行，每个试验在 2016 年重复三次，并在 2017 年重复。随着密度和竞争持续时间的增加，Parthenium 杂草生物量显着增加。增加的parthenium杂草密度对高粱生长、产量和产量贡献性状具有线性负面影响。最高的产量损失，高达 66%，记录在 20 株/m-2与无杂草处理相比。此外，这种杂草与高粱的长期竞争导致谷物产量比无杂草处理减少了 81%。根据我们的结果，parthenium 杂草的密度应控制在 5 株 m-2在高粱田的整个作物生长期间，即使在低密度和作物生长早期和后期的激烈竞争中，它也会导致严重的产量损失。