Revisão sistemática da literatura sobre germinação de sementes em Myrtaceae Neotropical

Abstract

Studies on the early life stage of plants are essential for understanding the survival and establishment requirements of flora. However, this information is rare for the neotropical flora. In megadiverse environments such as the Neotropics, it is expected the existence of a wide diversity of seed germination strategies. Myrtaceae is one of the richest botanical families in this region, with about 2,500 species. This family shows a huge morphological variation, including differences on fruit size, color, embryo type, and seeds quantity. Myrtaceae fruits are an important food source for animals due to their year-round availability. Additionally, many species, such as guava, pitanga, and jabuticaba, have socioeconomic value for human populations. Given the significance of this botanical family, we conducted a systematic literature review on seed germination in Neotropical Myrtaceae using three online repositories: Web of Science, Scopus, and Scielo Brazil. The main goal was to describe what we know about this early life stage of Myrtaceae seeds and to synthesize this knowledge to guide future researches on the topic. As a result of the review, 9,758 unique publications were found, and after screening for relevance to the topic, 151 studies met the inclusion criteria. These studies evaluated germination in 17 genera and 64 species, with Eugenia being the most studied genus. We found a spatial bias with a high concentration of studies in Brazil, where 120 papers (79.5%) were conducted, especially in the southern and southeastern regions. The most common objectives in the studies were testing germination at different temperatures (36 studies), testing the effect of storage methods on germination (32 studies), and testing tolerance to desiccation or drying seeds methods (30 studies). The germination criteria adopted by the authors varied; however, radicle protrusion was the most commonly used (45.3% of the studies) to establish that seed germination occurred. Most of the experiments (81.5%) were conducted in laboratories. The most commonly substrate applied in the experiments was paper (59.6% of studies), and the most frequent temperature was 25°C (57.6%). A total of 150 publications reported the germination percentage, and just over half of the studies presented data on the germination speed index, while fewer than half reported water content and mean germination time, which are important variables for understanding the germinative behaviour of plant species. Our results showed that more efforts are crucial to accurately describe Myrtaceae germination at a point that these studies could contribute to ecological restoration strategies. The lack of methodological consistency among the studies hinders the execution of a meta-analysis of the data already published, emphasizing the urgency to develop a consistent protocol for seed germination in Myrtaceae.