Light and Temperature Requirements for Common Cocklebur (Xanthium strumarium) Germination During After-Ripening under Field Conditions
Light and Temperature Requirements for Common Cocklebur (Xanthium strumarium) Germination During After-Ripening under Field Conditions
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DOI：
10.1614/ws-06-184
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发表时间：
2007-05
期刊：
影响因子：
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通讯作者：
J. Norsworthy;M. J. Oliveira
中科院分区：
文献类型：
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作者：
J. Norsworthy;M. J. Oliveira
摘要2002年和2003年进行了土壤热幅对苍耳出苗的影响试验。此外，在2003年和2004年秋季收集了常见的苍耳瘦果，以评估在田间条件下萌发超过12个月期间的光照和温度要求的变化。在控制条件下，从外地瘦果检索响应光环境和恒定和波动的温度进行了评价。遮荫强度与土壤热幅值呈线性负相关，可解释田间出苗2年以上变异的77%。出苗率随着土壤热幅的下降而下降，95%的遮荫导致出苗率下降72%至88%。红光和远红光对发芽都没有太大的影响，埋葬也没有引起光的需求。从土壤表面取回或埋在土壤中的瘦果的萌发一般不受红光或远红光的影响，瘦果没有获得红光的要求埋后。瘦果成熟后，每天暴露于24至30 ℃的自然温室光下对立即萌发是必需的，而在黑暗中不发生萌发。无论成熟后的时间或瘦果的检索深度，15 ℃的温度波动增加发芽率超过那些在恒温。在这两年的四月或五月和七月或八月，在所有样本日期的平均波动温度通常是25 C（17.5/32.5 C低温/高温; 15 C每日波动），这是最适合发芽的。发芽一般在35或40 ℃的恒温下最佳。在恒定温度下发芽所需的平均温度高于在波动温度下发芽所需的平均温度，这可能有助于减少春季和夏季的出苗，因为较早出现的杂草物种或作物已经确立，而发芽所需的温度波动降低了在光照减少的环境中出苗的可能性。名称：苍耳、苍耳Xanthium strumarium L. XANST
Abstract Experiments were conducted in 2002 and 2003 to determine the influence of soil thermal amplitude on common cocklebur emergence. Additionally, common cocklebur achenes were collected in fall of 2003 and of 2004 to assess changes in light and temperature requirements for germination over a 12-mo period under field conditions. Common cocklebur germination in response to the light environment and to constant and fluctuating temperatures were evaluated under controlled conditions following achene retrieval from the field. There was a linear inverse relationship between shade intensity and soil thermal amplitude, which explained 77% of the variability in emergence in the field over 2 yr. Emergence decreased as soil thermal amplitude declined, with 95% shading resulting in a 72 to 88% reduction in emergence. Neither red nor far-red light had much effect on germination, and burial did not induce a light requirement. Germination of achenes retrieved from the soil surface or buried in soil generally was not affected by red or far-red light, and the achenes did not acquire a red-light requirement following burial. Daily exposure to natural greenhouse light at 24 to 30 C was essential for germination immediately following achene maturation, whereas no germination occurred in darkness. A thermal fluctuation of 15 C increased germination percentages over those at constant temperatures regardless of time after maturation or retrieval-depth of achenes. The mean fluctuating temperature over all sample dates that was generally optimal for germination was 25 C (17.5/32.5 C low/high temperatures; 15 C daily fluctuation) in April or May and July or August in both years. Germination was generally optimum at constant temperatures of 35 or 40 C. The higher mean temperature requirement for germination at constant temperatures than at fluctuating temperatures likely contributes to reduced emergence in spring and summer months, when earlier emerging weed species or crops have already become established, and the thermal fluctuation requirement for germination reduces the likelihood of emergence in an environment where light availability is diminished. Nomenclature: Common cocklebur, Xanthium strumarium L. XANST