Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, USA.
Division of Seed Technology, ICAR - Indian Grassland and Fodder Research Institute, Jhansi, India.
Pest Manag Sci. 2021 Jun;77(6):2756-2765. doi: 10.1002/ps.6304. Epub 2021 Feb 15.
Italian ryegrass (Lolium perenne ssp. multiflorum) is one of the major winter annual weeds worldwide. In this research, diversity for seed morpho-physiological traits such as seed weight, seed size, awnedness, dormancy, speed of germination, and seed vigor among Italian ryegrass populations collected from the Texas Blacklands region were assessed, and potential association with herbicide resistance was investigated.
A high degree of diversity was observed among the populations for 100-seed weight (125-256 mg), seed length (4.8-6.6 mm), awn length (0-6 mm), and total seedling length (9-14 cm at 21 days after seed germination). Inter-population range for seed dormancy was higher in the freshly harvested seed (31-85%), which reduced to 18 to 62% at 9 months after harvest. Populations with high initial seed dormancy (> 70% dormancy) released dormancy at a faster rate than the low dormancy group (< 40%). Percent survival status to multiple postemergence herbicides was positively correlated with 100-seed weight and fresh or initial seed dormancy.
Early emerging cohorts are easily controlled by pre-plant tillage and preemergence herbicides, whereas late emerging cohorts (facilitated by seed dormancy) are exposed to postemergence herbicides wherein greater opportunities exist for resistance evolution, likely explaining the occurrence of high seed dormancy in Italian ryegrass populations resistant to postemergence herbicides. High seed weights can further allow seedling emergence from greater burial depth, thereby exposing more seedlings to postemergence herbicides and increasing the likelihood of resistance evolution. Results provide unique insights into the association between seed traits and herbicide resistance in this species. © 2021 Society of Chemical Industry.
意大利黑麦草（Lolium perenne ssp. multiflorum）是世界范围内主要的冬季一年生杂草之一。本研究评估了来自德克萨斯黑土地区的意大利黑麦草种群的种子形态生理特性多样性，如种子重量、种子大小、芒长、休眠、发芽速度和种子活力，并研究了与除草剂抗性的潜在关联。
在 100 粒种子重量（125-256 毫克）、种子长度（4.8-6.6 毫米）、芒长（0-6 毫米）和总幼苗长度（种子发芽后 21 天 9-14 厘米）方面，种群间表现出高度的多样性。收获后新鲜种子的种子休眠范围较大（31-85%），收获 9 个月后降至 18-62%。休眠率高（>70%休眠）的种群比休眠率低（<40%）的种群更快地解除休眠。对多种苗后除草剂的存活率状况与 100 粒种子重量和新鲜或初始种子休眠呈正相关。
早期出苗的群体很容易被播前耕作和播前除草剂控制，而晚期出苗的群体（由休眠促进）则暴露在苗后除草剂中，这为抗性进化提供了更多的机会，这可能解释了意大利黑麦草种群对苗后除草剂高休眠的发生。高种子重量还可以使幼苗从更大的埋藏深度出苗，从而使更多的幼苗暴露在苗后除草剂下，增加抗性进化的可能性。结果为该物种中种子特性与除草剂抗性之间的关联提供了独特的见解。 © 2021 化学工业协会。
