College of Ecology, Lishui University, Lishui, China.
Rural Industry Development Center of Liandu District, Lishui, China.
PLoS One. 2021 Dec 2;16(12):e0260674. doi: 10.1371/journal.pone.0260674. eCollection 2021.
Conyza sumatrensis (Retz.) E. H. Walker is an obnoxious weed, emerging as an invasive species globally. Seed germination biology of four populations of the species stemming from arid, semi-arid, temperate, and humid regions was determined in this study. Seed germination was recorded under six different environmental cues (i.e., light/dark periods, constant and alternating day and night temperatures, pH, salinity, and osmotic potential levels) in separate experiment for each cue. Populations were main factor, whereas levels of each environmental cue were considered as sub-factor. The impact of seed burial depths on seedling emergence was inferred in a greenhouse pot experiment. Seed germination was recorded daily and four germination indices, i.e., seed germination percentage, mean germination time, time to reach 50% germination, and mean daily germination were computed. Tested populations and levels of different environmental cues had significant impact on various seed germination indices. Overall, seeds stemming from arid and semi-arid regions had higher seed germination potential under stressful and benign environmental conditions compared to temperate and humid populations. Seed of all populations required a definite light period for germination and 12 hours alternating light and dark period resulted in the highest seed germination. Seed germination of all populations occurred under 5-30°C constant and all tested alternate day and night temperatures. However, the highest seed germination was recorded under 20°C. Seeds of arid and semi-arid populations exhibited higher germination under increased temperature, salinity and osmotic potential levels indicating that maternal environment strongly affected germination traits of the tested populations. The highest seed germination of the tested populations was noted under neutral pH, while higher and lower pH than neutral had negative impact on seed germination. Arid and semi-arid populations exhibited higher seed germination under increased pH compared to temperate and humid populations. Seed burial depth had a significant effect on the seedling emergence of all tested populations. An initial increase was noted in seedling emergence percentage with increasing soil depth. However, a steep decline was recorded after 2 cm seed burial depth. These results indicate that maternal environment strongly mediates germination traits of different populations. Lower emergence from >4 cm seed burial depth warrants that deep burial of seeds and subsequent zero or minimum soil disturbance could aid the management of the species in agricultural habitats. However, management strategies should be developed for other habitats to halt the spread of the species.
苏门白酒草（Retz.）E. H. Walker 是一种讨厌的杂草，作为一种入侵物种在全球范围内出现。本研究确定了来自干旱、半干旱、温带和湿润地区的四个种群的种子萌发生物学特性。在每个 cue 的单独实验中，记录了六种不同环境线索（即光照/黑暗期、恒定和交替的昼夜温度、pH 值、盐度和渗透压水平）下的种子萌发情况。种群是主要因素，而每个环境 cue 的水平被认为是亚因素。在温室盆栽实验中推断了种子埋藏深度对幼苗出土的影响。每天记录种子萌发情况，并计算了四个萌发指数，即种子萌发率、平均萌发时间、达到 50%萌发所需时间和平均日萌发率。不同环境 cue 的测试种群和水平对各种种子萌发指数有显著影响。总体而言，与温带和湿润种群相比，来自干旱和半干旱地区的种子在胁迫和良性环境条件下具有更高的种子萌发潜力。所有种群的种子都需要一定的光照期才能萌发，12 小时的交替光照和黑暗期导致最高的种子萌发。所有种群的种子都在 5-30°C 的恒定温度和所有测试的交替昼夜温度下萌发。然而，在 20°C 下记录到最高的种子萌发。干旱和半干旱种群的种子在温度、盐度和渗透压水平升高的情况下表现出更高的萌发率，这表明母体环境强烈影响了测试种群的萌发特征。测试种群的最高种子萌发发生在中性 pH 值下，而高于和低于中性 pH 值对种子萌发有负面影响。与温带和湿润种群相比，干旱和半干旱种群在 pH 值升高的情况下表现出更高的种子萌发率。种子埋藏深度对所有测试种群的幼苗出土有显著影响。随着土壤深度的增加，幼苗出土率呈初始增加。然而，在 2 cm 的种子埋藏深度后，记录到急剧下降。这些结果表明，母体环境强烈调节不同种群的萌发特征。>4 cm 的种子埋藏深度导致的低萌发率表明，种子的深埋藏和随后的零或最小土壤干扰可能有助于农业生境中该物种的管理。然而，应该为其他生境制定管理策略以阻止该物种的传播。
