Itchgrass [Rottboellia cochinchinensis (Lour.) W.D. Clayton] is among the most troublesome weeds in subtropical climates where sugarcane (Saccharum spp. interspecific hybrids) is cultivated. Two R. cochinchinensis biotypes commonly infest sugarcane in Louisiana. The Louisiana-1 biotype is daylength neutral, but Louisiana-2 flowered when daylength decreased to 13 h. Coupled with biotype diversity, seedling emergence has been reported to occur earlier in the growing season, as sugarcane emerged from winter dormancy. Both R. cochinchinensis biotypes were established in a common garden experiment in Louisiana during periods of sugarcane development and field preparation to simulate discontinuous emergence. Plant height and raceme production were recorded weekly for each biotype and establishment timing; aboveground biomass was harvested in autumn. Louisiana’s subtropical humid climate stimulated rapid plant growth that typically began in May and persisted through September. Without sugarcane competition, maximum R. cochinchinensis heights for Louisiana-1 and Louisiana-2 were 206 and 179 cm and growing degree days to 20-cm height in 2017 ranged from 546 to 832 and 865 to 1,160, respectively. Slower initial growth reported with Louisiana-2 would allow more time for growers to treat escaped plants with POST herbicides. Total raceme production, by autumn, was zero for Louisiana-2 established in June or later, but Louisiana-1 established in June produced up to 202 racemes. The present study demonstrated the importance of managing the Louisiana-2 biotype in March and April to limit seed production, but fields infested with Louisiana-1 were at greater risk for potential crop yield loss, because plants produced high quantities of seed when established over a wide period of time.

中文翻译：

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建立时间对路易斯安那州生长的两种 itchgrass (Rottboellia cochinchinensis) 生物型生长和繁殖力的影响

痒草 [铁线莲(Lour.) WD Clayton] 是亚热带气候中最麻烦的杂草之一，甘蔗 (甘蔗spp. 种间杂种）被栽培。二R. cochinchinensis生物型通常感染路易斯安那州的甘蔗。Louisiana-1 生物型是日照中性的，但 Louisiana-2 在日照减少到 13 小时时开花。再加上生物型的多样性，据报道，由于甘蔗从冬季休眠中出现，幼苗出现在生长季节的早期。两个都R. cochinchinensis在路易斯安那州的一个普通花园实验中，在甘蔗发育和田间准备期间建立了生物型，以模拟不连续的出苗。每周记录每种生物型和建立时间的植物高度和总状花序产量；秋季收获地上生物量。路易斯安那州的亚热带潮湿气候刺激了植物的快速生长，这种生长通常从 5 月开始，一直持续到 9 月。没有甘蔗竞争，最大R. cochinchinensisLouisiana-1 和 Louisiana-2 的高度分别为 206 和 179 厘米，2017 年到 20 厘米高度的生长期天数分别为 546 至 832 和 865 至 1,160。Louisiana-2 报告的较慢的初始生长将使种植者有更多时间用 POST 除草剂处理逃逸植物。到秋天，6 月或更晚建立的 Louisiana-2 的总总状花序产量为零，但 6 月建立的 Louisiana-1 产生了多达 202 个总状花序。本研究证明了在 3 月和 4 月管理 Louisiana-2 生物型以限制种子生产的重要性，但被 Louisiana-1 侵染的田地面临更大的潜在作物减产风险，因为植物在种植后会产生大量种子很长一段时间。