Sample size in studies on the germination process

Abstract

Studies on diaspore germination in native species with low economic relevance but great ecological significance have been based on a wide range of sample sizes. However, can the sample size change the physiological inferences made from germination measurements? To answer this question, diaspores of six Cerrado species were evaluated for germinability, germination time (initial, mean, and final), germination velocity (mean germination rate and Maguire’s rate), coefficient of variation of the germination time, and synchronization index of the germination process. Germinability, final time, mean time, and synchronization index were robust with respect to sample size fluctuation. Maguire’s rate, initial time, coefficient of variation of the germination time, and mean germination rate, in contrast, were affected by sample size fluctuation, at least in one of the species tested. The robustness of the time measurements and the synchronization index also demonstrates that the germination process occurs in a cadenced rhythm, much like a biological clock. Among the measurements evaluated, Maguire’s rate is the only one that must be avoided, since it is strongly influenced by sample size and by the balance between germinability and mean germination rate. These results demonstrate that sample size can affect inferences about the germination process and can compromise restoration and (or) conservation efforts.

Ex situ initial seedling development of Hymenaea courbaril L. (Fabaceae): a crucial phase to preserve the species

“…The seedling emergence of Hymenaea courbaril is slow and asynchronous even without mechanical dormancy, which was removed through mechanical scarification. The range between the first and last emergence, the higher mean emergence time and uncertainty, and lower Z values in relation to other native species confirm this information, although there are slower and more asynchronous species than this (Carvalho et al 2005, Pereira et al 2009, Mendes-Rodrigues et al 2011a, b, Dorneles et al 2013, Ribeiro-Oliveira et al 2013, Berger et al 2014, Ribeiro-Oliveira & Ranal 2016.…”

Clues on an intraspecific communication system in early plant establishment: The seed-seedling transition from the point of view of a crosstalk between information theory and gene expression

“…These aspects, which have long been discussed by ecophysiologists (e.g. Peet, 1975), may come from physiological processes associated with maternal recruitment, as well as from the seed, such as volatile emission (Ribeiro-Oliveira and Ranal, 2016). In either way, there are still few reports that decipher how this effect of mutual stimulation promotes the germination boom, and information entropy can stand out as a useful measurement for this.…”

“…Thus, we can say that the intra-specific variability in a seed sample is a central component on multiple interactions in a seed-seedling transition system (Labouriau and Valadares, 1976). This interaction is theoretically more intense in artificial environments (e.g., Petri dish, germination plastic boxes and development chamber), where it is expected that populational density will be greater than in natural environments (Labouriau and Valadares, 1976; Ribeiro-Oliveira and Ranal, 2016). Taking this into account, we ask: how can intra-specific variability affect functional understanding of the germination process?…”

“…This can be related to different aspects, such as modifications in water uptake, presence of volatile (mainly VOCs and/or volatile hormones, such as ethylene and jasmonates) and substrate structure (Matilla, 2000; Linkies and Leubner-Metzger, 2012; Motsa et al , 2017; Maurya et al , 2019). In this view, it is expected that the higher the number of random events in the seed-seedling transition system, the greater the information entropy generated (Ribeiro-Oliveira and Ranal, 2016). Thus, findings in seed-seedling transition systems not only can shed light on the understanding of the functional association between information entropy and the early plant development, but also help produce reliable models of theoretical biological systems, an incipient topic in seed science.…”

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“…This seems to be quite conflicting because normal approximation for large samples is considered as a basis of the nonparametric statistics (Zar, 1999). Because of the inability of non-parametric tests to minimise type I and type II errors (Lix et al 1996), these tests are considered inefficient compared to its parametric analogous in inferential statistics (Ribeiro- Oliveira et al 2013;Ribeiro-Oliveira and Ranal, 2016).…”