In conservation agriculture, weed seed germination could decrease with the presence of a cover crop, surface weed seed location and temporal drought in summer just after seed shedding. This study simultaneously examined the effects of a cover crop, burial depth (seed location) and hydric stress on weed emergence and early growth. It was hypothesized that drought would reduce weed emergence and the initial growth of weed seeds and that this effect would be greater when the seeds were on the soil surface and in the presence of a cover crop. Four annual weed species were chosen that are frequently found (Anisantha sterilis, Vulpia myuros, Sonchus asper, Veronica persica) and not frequently found (Alopecurus myosuroides, Poa annua, Cyanus segetum, Capsella bursa‐pastoris) in fields that implement conservation agriculture. The unburied seeds had 26% lower emergence, on average, than the buried seeds (significant for six of the eight species), hydric stress reduced emergence by 20% (for seven of the eight species) and the presence of a cover crop reduced the level of emergence by 17% (for all species). The unburied seeds with hydric stress were emerging under the “most stressful” set of factors, with a 45% decrease in emergence, compared with the seeds emerging under the “least stressful” set of factors (buried seeds without hydric stress). All the weed growth measurements (height, dry matter content and number of leaves) decreased with the presence of a cover crop. The species that are found frequently in the fields that implement conservation agriculture, compared with the species that are not frequently found in conservation agriculture fields, had higher rates of germination and a higher tolerance of hydric stress when their seeds were unburied.

中文翻译：

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干旱对杂草出苗和生长的影响随种子埋藏深度和覆盖作物的存在而变化

在保护性农业中，杂草种子的发芽可能会随着覆盖作物的存在，表层杂草的种子位置和种子脱落后的夏季短暂干旱而减少。这项研究同时检查了覆盖作物，埋葬深度（种子位置）和水分胁迫对杂草出苗和早期生长的影响。据推测，干旱将减少杂草的出现和杂草种子的初始生长，并且当种子在土壤表面并且有覆盖作物时，这种影响会更大。四种年度杂草进行选择频繁被发现（Anisantha sterilis，鼠茅，花叶滇苦菜，婆婆纳），而不是经常发现（看麦娘，美洲大麦（Poa annua），菜青（Cyanus segetum），s菜（Capsella bursa-pastoris））实施保护性农业的领域。未埋种子的平均出苗率比埋种子（八种中的六种显着）低26％，水胁迫使出苗减少20％（八种中的七种），而覆盖作物的存在降低了种子的出苗率。出现水平提高了17％（针对所有物种）。与处于“最低压力”因素组下的种子（无水力的埋藏种子）相比，具有“水胁迫”状态的未埋种子在“最胁迫”的一组因素下出苗，出苗率降低了45％。所有的杂草生长测量值（高度，干物质含量和叶数）都随着被覆作物的存在而降低。在实施保护性农业的领域中经常发现的物种，