Water Hyacinth in Lake Tana

Biomass survey of water hyacinth helps to show major morphometric characters and biomass of the weed. Typically, the biomass of water hyacinth was collected using quadrats with a specific unit area placed over the plant mat (Robles et al., 2015). Water hyacinth samples were collected once via quadrant having an area of 0.5m2. For this study, a destructive biomass estimation method was used to collect the samples. The samples of the weed were measured to estimate the morphometric characteristics of water hyacinth in the study area. Morphometric characteristics of a randomly selected single water hyacinth plant was measured from each quadrant (Robles et al., 2015). The data collection was held twice at October and May when the peak and down water hyacinth infestation occur, respectively. Tape meter was used to measure leaf length, root and shoot length of water hyacinth sample while leaf blade area of the weed was estimated via ImageJ 5.3 software. In addition, the weight of each quadrant was measured using weight scale to capture wet biomass of water hyacinth. According to Madsen (1993) water content of water hyacinth biomass can be dried with a minimum of 500C for considerable enough time. Hence, the weed was dried in an oven at 650C (Center and Spencer, 1981) for 48 hours to remove all the water from the water hyacinth.凤眼蓝（Water Hyacinth）生物量调查可用于揭示该入侵杂草的主要形态计量特征与生物量水平。通常而言，研究人员会通过在植株覆盖层上放置特定单位面积样方（quadrat）的方式采集凤眼蓝生物量样本（Robles等，2015）。本研究采用面积为0.5平方米的样方单次采集凤眼蓝样本，并使用破坏性生物量估算方法开展样本采集工作。对采集的杂草样本进行测量，以估算研究区域内凤眼蓝的形态计量特征：从每个样方中随机选取单株凤眼蓝，测量其形态计量特征（Robles等，2015）。数据采集分别于10月和5月开展两次，分别对应凤眼蓝侵染的峰值期与消退期。研究使用卷尺测量凤眼蓝样本的叶长、根长与茎长，并通过ImageJ 5.3软件估算该杂草的叶面积。此外，使用称重秤测量每个样方内的总重量，以获取凤眼蓝的鲜生物量。根据Madsen（1993）的研究，凤眼蓝生物量的水分可通过置于至少50℃环境中烘干足够时长以充分去除；因此本研究将杂草样本置于65℃烘箱中烘干48小时，以完全去除凤眼蓝中的水分（Center和Spencer，1981）。