DOI: 10.5061/dryad.gtht76hwv
title: Data from: Nitrate inhibition of germination in Ericaceae relates to seed size and mycoheterotrophy

description: Nitrate is a well-known regulator of several processes in plants,
 including seed germination. It generally induces germination, but its
 effect is species-specific, and germination of some species is even
 inhibited. It is not clear what drives these
 differences. Nevertheless, it is striking that the germination of
 initially mycoheterotrophic orchids is generally inhibited by nitrate,
 indicating that this may be an adaptive trait allowing the seeds to detect
 sites with low nutrient availability, favourable for mycoheterotrophic
 plants. Whether this unusually negative response to nitrate is a general
 feature of mycoheterotrophic plant germination remains
 unknown. We focused on the family Ericaceae, which contains
 lineages that are either fully or initially mycoheterotrophic together
 with autotrophic ones, and we tested the germination response of selected
 species to nitrate. We found high variability in the germination responses
 even within members of this family. Fully and initially mycoheterotrophic
 species reacted more negatively to nitrate compared to autotrophic
 species. However, the species responses to nitrate also strongly
 correlated with seed dimensions. As a control, we also tested responses to
 another common nitrogen form, ammonium ion, but these showed little or no
 correlations with the tested predictors indicating that the observed
 germination responses are specific to nitrate. Two factors may be
 responsible for the negative response of mycoheterotrophic species of both
 Ericaceae and orchids to nitrate: seed size and the mode of carbon
 acquisition (mycoheterotrophy), nevertheless, both factors are closely
 linked. Thus, mycoheterotrophic plants in general, which nearly all
 produce tiny dust seeds, are likely to be negatively affected by
 nitrate. 
description: Seeds were cultivated axenically in vitro on media with various
 amount of nitrate or ammonium ion. We also measured dimensions of dry ripe
 seeds. 
description: # Nitrate inhibition of germination in Ericaceae relates to seed size and
 mycoheterotrophy
 [https://doi.org/10.5061/dryad.gtht76hwv](https://doi.org/10.5061/dryad.gtht76hwv) ## Description of the data and file structure The seeds were cultivated axenically in vitro on media with various concentration of nitrate or ammonium ion to count germination rate. We also measured dimensions of ripe seeds. ### Files and variables #### File: klicivosti.txt **Description:**  ##### Variables * species: plant species tested * ion: the ion tested - nitrate (NO3-) or ammonium (NH4+) * concentration: the concentration of the tested ion in mg·l-1 of NO3- or NH4+ [mg·l-1]. * germination_rate: the proportion of germinated seeds counted after cultivation [%]. #### File: seed\_dimensions.txt **Description:**  ##### Variables * plant: plant species tested * coat_length: total length of the seed [mm] * coat_width: total width of the seed [mm] * live_length: length of the living part (embryo plus endosperm, if present; excluding seed coat) [mm] * live_width: width of the living part (embryo plus endosperm, if present; excluding seed coat) [mm] ## Code/software Both datasets are tab separated txt files ready to be open in any version of R software. They can also be open in Excel or other common software.