Contrasting responses of seed germination to fire have been reported in different vegetation worldwide. In Brazil, the Pantanal harbors one of the world's most extensive floodplains, marked by flooding periods alternating with a dry fire-prone season. The present study aimed to understand the role of fire on regeneration from seed in the Pantanal wetland, using two pioneer species displaying physically dormant seeds as study models: Sesbania virgata (Cav.) Pers. and Guazuma ulmifolia Lam. Seeds were subjected to (1) heat shocks and (2) experimental burns, besides the controls. In Experiment 1, heat shocks of 65, 85, 105, 125, and 145°C (all treatments ± 5°C), were applied for 5 minutes of exposure. In Experiment 2, seeds and corky fruits were placed upon the soil surface, and seeds were buried at 2 cm belowground, then subjected to experimental burns. Germination trials were conducted under optimal conditions and recorded the proportions of germinated, hard, and dead seeds. Increasing temperature of heat shocks had an increasingly negative effect on seed water content and germination of both species as well as increasing the proportion of dead seeds. A slight enhancement in germination of buried seeds (18%) was found in the experimental burns for S. virgata seeds. Moreover, buried seeds remained hard (dormant) up to 80 and 40% for S. virgata and G. ulmifolia, respectively. Inside the corky fruits, seed germination was not promoted and there was a decrease in the proportion of hard seeds after burning, while direct exposure to fire killed nearly all seeds placed upon the soil surface. Fire has little to no effect on the enhancement of seed germination, but seeds mainly survive when buried belowground. Our study provides crucial information to understand seed tolerance to increased fire occurrence in disturbed tropical wetlands.

在世界各地的不同植被中，已经报道了种子发芽对火的不同反应。在巴西，潘塔纳尔湿地是世界上最泛滥的洪泛区之一，其特征是洪水时期与干旱多发季节交替出现。旨在了解火灾对再生过程中的作用，从种子本研究潘塔纳尔湿地，使用两个先锋树种显示物理休眠的种子为研究模型：田菁虎尾草（CAV）个人 和Guazuma ulmifolia我是。除对照外，种子还受到（1）热冲击和（2）实验性灼伤。在实验1中，将65、85、105、125和145°C的热冲击（所有处理均±5°C）施加了5分钟的暴露时间。在实验2中，将种子和树皮果实放在土壤表面，将种子埋在地下2 cm处，然后进行实验性烧伤。在最佳条件下进行了发芽试验，并记录了发芽，坚硬和死亡种子的比例。热激温度的升高对两种植物的种子含水量和发芽率均产生越来越大的负面影响，并增加了死种子的比例。在S. virgata的实验性烧伤中发现埋藏种子的发芽略有增强（18％）种子。此外，沙丁鱼（S. virgata）和短叶草（G. ulmifolia）的埋藏种子仍然保持休眠状态（休眠），分别高达80％和40％。在软木塞果实内部，没有促进种子发芽，燃烧后硬种子的比例减少了，而直接暴露于火中几乎杀死了置于土壤表面的所有种子。火对增强种子发芽几乎没有影响，但种子主要是埋在地下才能生存。我们的研究提供了重要的信息，以了解种子耐受性，以防止热带湿地受火的增加。