Impact of fruit orientation and pelleting material on water uptake and germination performance in artificial substrate for sugar beet.

Sebastian Blunk,Sandra Brosda,Jeroen Hoffer,Martine I De Heer,Sacha J Mooney,Craig J Sturrock

doi:10.1371/journal.pone.0232875

Abstract

Water uptake into seeds is a fundamental prerequisite of germination and commonly influenced by commercial seed enhancement technologies. The effect of fruit orientation and contrasting pelleting materials on germination and biological performance of sugar beet was assessed. The results indicated there was orientation dependent fruit shrinkage of 37% for the operculum side supplied by moisture compared to 4% for the basal pore side. The expansion rate of 5% compared to the original size, which was also observed for non-shrinking seeds, indicated this was a temporary effect. This behaviour has importance for the application pelleting materials to seeds. Pellets composed of materials exhibiting low levels of swelling act as a water distribution layer which increased germination rates. Careful selection of pelleting material is crucial as it has direct implications on germination speed and subsequent establishment rates.

Highlights

When seeds enter a moist soil environment, the process of imbibition begins and germination is initiated upon contact of the dry seed surface to the moist soil matrix
A shorter amount of time was needed until the inflection point was reached for the operculum touching the moist surface, indicating the basal pore does not represent the primary way of water uptake
This contradicts a common assumption that the basal pore is one of the major entry points of water uptake besides the micropyle as the pericarp mainly consists of an impervious layer of sclerenchyma cells [44]

Summary

Introduction

When seeds enter a moist soil environment, the process of imbibition (i.e. water uptake) begins and germination is initiated upon contact of the dry seed surface to the moist soil matrix. The true seed (embryo, perisperm and testa) is encapsulated in the pericarp, the fruit coat (dense sclerenchyma cells) containing the basal pore (loose cells) and the ovary cap (operculum) (Fig 1) [1]. Water uptake is proposed to be facilitated by the micropyle, a small hole allowing entry of water, the basal pore (former connection of the seed to the mother plant) and the operculum [2].

Objectives

Methods

Results

Discussion

Conclusion