Density-dependent effect of allelopathy on germination and seedling emergence in two Ipomoea species

Zoila Mercedes Aguilar-Franco,Irene Perea-Arango,Alejandro Flores-Morales,Susana Valencia-Díaz,Alejandro Flores-Palacios,José De Jesús Arellano-García

doi:10.1186/s40693-019-0087-z

Zoila Mercedes Aguilar-Franco, Irene Perea-Arango + Show 4 more

Open Access

https://doi.org/10.1186/s40693-019-0087-z

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Abstract

BackgroundDensity in inter and intraspecific plant-plant interactions affects the action modes of allelopathy (autotoxicity, negative and positive allelopathy). Some seeds exude compounds that inhibit the germination of others. Ipomoea murucoides and I. pauciflora are sympatric tree species that form patches at the local scale where one or the other dominates, possibly due to allelopathy in the seeds. The objective of this study was to determine the possible density-dependence of the allelopathic effect among seeds of these species through the measure of seed germination and seedling emergence.MethodsIn both species, allelopathy was measured as: a) germination in mixed sowing of both species at different proportions, b) germination in single-species trials at different densities after adding seed extracts of both species, and c) seedling emergence in seed mixtures of both species sown at different proportions beneath canopies of the two Ipomoea species.ResultsSeed germination of I. murucoides was increased by the presence of I. pauciflora and diminished at higher densities of its own seeds; however, seed germination of I. pauciflora was not affected by the presence of I. murucoides seeds. The addition of extracts (either from conspecifics or congeneric) diminished the germination of both species and at higher seed densities the germination was lower. Seedling emergence did not depend on the species under which the seeds were sown nor on the density of the seeds.ConclusionsThe germination experiments evidenced positive allelopathy and/or autotoxicity, while there was no evidence of allelopathic effects in seedling emergence. The allelopathic activity is reported in the seeds of these species for the first time.

Highlights

Density in inter and intraspecific plant-plant interactions affects the action modes of allelopathy
No consistent pattern of germination in relation to seed density was observed in the three controls; for example, with 8 mL of distilled water, germination of I. murucoides increased with seed density but germination of I. pauciflora did not
With 12 mL I. pauciflora had the lowest germination at intermediate density, while with 16 mL the germination of both species diminished with the increment of seed density (Fig. 2c, d, e, h, i, j)

Summary

Introduction

Density in inter and intraspecific plant-plant interactions affects the action modes of allelopathy (autotoxicity, negative and positive allelopathy). Some seeds exude compounds that inhibit the germination of others. Ipomoea murucoides and I. pauciflora are sympatric tree species that form patches at the local scale where one or the other dominates, possibly due to allelopathy in the seeds. The objective of this study was to determine the possible density-dependence of the allelopathic effect among seeds of these species through the measure of seed germination and seedling emergence. A negative form of intraspecific allelopathy, called autotoxicity or autoallelopathy, occurs when plants exert harmful effects on the growth of its conspecifics [19]. It has been found that diterpenes from leaves of Cistus ladanifer inhibited the seed germination, seedling size and seedling establishment at intraspecific level [20]

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