Straw interference in the emergence of talquezal seeds from different origins

Abstract Background: Talquezal (Paspalum virgatum L.) has become one of the main pasture weeds due to its association with the Urochloa brizantha death syndrome, a disease that causes the progressive death of clumps of susceptible grasses in patches, which leads to weed colonization and pasture degradation. Understanding the weed emergence pattern is essential in decision making for management strategies. Objective: Thus, this study aimed to evaluate the emergence pattern of talquezal seedlings according to its origin and the amount of straw covering the soil. Methods: The experiment was carried out in a greenhouse in a completely randomized design, with six replications and treatments arranged in an 8 × 3 factorial scheme with eight amounts of Urochloa brizantha straw covering the seeds (0, 0.5, 1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 ton ha-1) and three collection sites (Rondonópolis, Redenção, and Cacoal). The effect of the origin and amount of straw was evaluated by the percentage of emergence, relative emergence frequency, mean emergence time, emergence synchrony, and emergence speed index of seedlings obtained over 35 days after sowing. Results: Talquezal seeds showed high seedling emergence vigor regardless of their origin under amounts of straw lower than 4.0 ton ha-1. Conclusions: The result suggests that the amounts of U. brizantha straw higher than 4.0 ton ha-1 on the soil surface, the lower is the percentage of Talquezal seedling emergence.

摘要 背景：塔尔奎扎尔草（Talquezal，Paspalum virgatum L.）因与巴西臂形草（Urochloa brizantha）枯萎综合征相关，已成为牧场主要杂草之一。该病害会导致易感草株斑块状丛簇渐进性死亡，进而引发杂草定植与牧场退化。明确该杂草的出苗模式，是制定杂草管理策略的核心依据。
目的：本研究旨在探究塔尔奎扎尔草的幼苗出苗模式，分析其种子来源与土壤秸秆覆盖量对出苗的影响。
方法：本试验于温室中开展，采用完全随机设计，设置6次重复，处理组合为8×3析因设计：8个巴西臂形草秸秆覆盖量梯度（0、0.5、1.0、2.0、4.0、6.0、8.0、10.0 吨·公顷⁻¹），以及3个种子采集位点（龙多诺波利斯、雷德桑托、卡科阿尔）。于播种后35天内，通过出苗率、相对出苗频率、平均出苗时间、出苗同步性及出苗速率指数，评估种子来源与秸秆覆盖量的效应。
结果：当秸秆覆盖量低于4.0吨·公顷⁻¹时，无论种子来源如何，塔尔奎扎尔草种子均表现出较高的幼苗出苗活力。
结论：研究结果表明，当土壤表面巴西臂形草秸秆覆盖量高于4.0吨·公顷⁻¹时，塔尔奎扎尔草幼苗出苗率会显著降低。