Effect of storage on seed viability and vigour in different Ethiopian wheat and maize cultivars

[摘要] English: Seed viability and vigour loss during storage, is one of the several factorslimiting crop yield in Ethiopia. Ambient storage conditions (high temperatureand relative humidity) as well as high moisture content during storage areconsidered to be the most important factors causing inferior quality of seeds(Anonymous, 1995). This supplied the rationale to study the effect of ambienttemperature (more or less similar to that applying in Ethiopian conditions) andlow temperature (4°C) on seed viability and vigour as well as biochemical andphysiological aspects related to seed viability and vigour of Ethiopian bread anddurum wheat as well as maize cultivar seeds. Additionally, the effects ofstorage in open and closed containers at different temperatures were alsoinvestigated.Seeds from three bread and durum wheat as well as two maize cultivars werestored at low (4°C) or ambient temperatures (18-30°C) in open or closedcontainers for a period of six months. Seed viability and vigour as well asbiochemical and physiological aspects related to seed viability and vigour weremeasured before (fresh seeds) and after different storage treatments. Seedviability (germination percentage) and vigour (germination index and dry shootmass) of seeds from both bread and durum wheat cultivars stored in opencontainers at ambient temperature were not significantly influenced while theother storage treatments affected the viability and vigour to various degrees.A more or less similar tendency was observed for seeds of the two maizecultivars, when only the raw data was considered. The mentioned storagecondition also maintained most of the seed metabolite levels measured in thisstudy. The lower relative humidity of the ambient storage environment contributedto maintain the moisture level of seeds at a much lower level compared to thoseaged at low temperature. This situation contributed to seeds aged in opencontainers at ambient temperature in retaining their viability and vigour duringthe six month storage period, indicating the need to dry seeds to a lowermoisture content level before storage and/or the need for dehumidifying thestorage environment, especially under Ethiopian storage conditions.Like the other two vigour tests, the measurement of electrical conductivity andthe respiration rate clearly showed cultivar variations. However, they did notseem to clearly distinguish between the vigour of seeds stored under differentconditions. Future work should focus towards developing a range of correlatingseed vigour test methods under local conditions. In addition, the results oflaboratory seed vigour tests should be correlated with field emergence in orderto assess the quality of seeds with respect to its field performance potential.Biochemical tests performed in this study did not seem to correlate with theviability and vigour of seeds aged under different conditions. However, therelatively higher metabolite content of some cultivars, such as HAR-1685 (breadwheat) and E-26 (durum wheat) appeared to have contributed to their higherviability and vigour. Future research might focus on elucidating the biochemicaland physiological processes underlying seed deterioration and considerdeveloping new and cheaper screening methods for seed viability and vigour. Itshould also be considered to correlate future findings regarding physiologicalchanges in stored seeds with mechanisms of seed deterioration in order tounderstand the mechanism of seed deterioration better in terms of biochemicalprocess and metabolite content changes.

[发布机构] University of the Free State