Seedless fruits mask germination response to key environmental factors

<p>In studies on the reproduction and germination of species with indehiscent fruits containing a single seed, it is often assumed that all fruits that reach maturity contain a seed capable of generating a new plant. This is not always the case, and failing to take this into account can lead to erroneous conclusions regarding the factors affecting reproduction or germination in plants.</p> <p>The research team illustrates this issue by analysing the effects of temperature, soil water potential and light exposure on the germination of <i>Salvia rosmarinus</i> fruits from four different populations, which vary in the proportion of empty fruits. When considering all fruits, we detected a negative effect of water potential in three of the four populations but no effect of temperature. However, when considering only the fruits with seeds, we detected a negative effect of water potential in all populations, as well as a positive response to increased temperature in three of them. In the temperature and light experiment, we observed that darkness reduced germination in three of the four populations when using all the fruits, but, when using only the fruits with seeds, we observed this negative effect in only one population. Despite this greater consistency of results across populations, differences persisted between populations regarding the effect of various factors on germination. These differences appear to be more a consequence of the reduced number of replicates remaining after removing empty fruits from the analyses than of any possible local adaptation of the populations. All these inconsistencies and incoherences found in this study highlight the danger of drawing conclusions from experiments and observations that do not account for the presence of seedless fruits in the samples.</p>