Seed moisture content can be used to accelerate dormancy release during after-ripening of Urochloa humidicola cv. Llanero spikelets

Fabiana Lima Abrantes,Nelson Barbosa Machado-Neto,Ceci Castilho Custódio

doi:10.1590/0103-8478cr20200526

Abstract

ABSTRACT: Increased demand for livestock products is leading to research on more productive pastures adapted to different environments. Urochloa humidicola is a species adapted to low-fertility conditions and to environments occasionally subjected to temporary flooding and with highly dormant seeds at harvest. Mechanical and sulphuric acid (H2SO4) scarification are used to release these seeds from dormancy; although, there are several side effects. Hydrogen peroxide (H2O2) is linked to dormancy release in many crop species. The objective of this research was to characterize the dormancy release and H2O2 accumulation during one year of storage in dormant spikelets of U. humidicola cv. Llanero equilibrated to 4.5% and 50% relative humidity (RH) and stored at 20 °C, during which time the seeds had moisture contents (MCs) of 0.03 and 0.1 g H2O g-1 dry weight (DW), respectively. The seeds were evaluated initially and at 3, 6 and 12 months; the seeds from spikelets or just caryopses were evaluated. Germination and dormancy percentage, H2O2 content, superoxide dismutase (SOD) and peroxidase (PRX) activity were determined. The germination and H2O2 content increased mainly in the caryopses, and SOD activity increased. Moreover, dormancy and PRX activity decreased during storage. For the first time, it was shown, in U. humidicola cv. Llanero that dormancy release during storage is caused mainly by the accumulation of reactive oxygen species (ROS) in the spikelets even under ultra-dry storage conditions (4.5% RH), and this process could be accelerated by seed storage at a MC of 0.1 g H2O g-1 DW at 20 °C.

Highlights

The increasing demand for livestock products is driven by population growth, increased richness and urbanization, especially in developing countries
With respect to the caryopses germination, no difference was detected between the storage environments, and the maximum germination was reached at six months of storage (Table 1)
The maximum germination of the spikelets was achieved after 12 months of storage, regardless of the storage relative humidity (RH), but, the dormancy release was faster in the moister environment than under dry conditions

Summary

Introduction

The increasing demand for livestock products is driven by population growth, increased richness and urbanization, especially in developing countries. This global demand is projected to increase by approximately 70% by 2050 to meet an estimated population of 9.6 billion. The larger part of this demand will be achieved through intensive livestock production (concentrated animal feeding operations) and traditional systems (animals raised in pastures). V.51, n.1, The increase in animal production in Brazil is due to technological advances related to genetics, animal nutrition and pasture quality. Brachiaria) spp. have been increasing in area, mainly because of the robustness and adaptability of these species to a range of both climate and soil conditions (CARDOSO et al, 2014)

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