Seed germination and storage reserves of maize and sorghum after exposure to and recovery from pre- and post-flowering dehydration

Abstract

Investigations were made on the seed viability (standard germination test and vigour after accelerated ageing) and seed quality (starch, protein, lipid, sucrose, glucose and fructose) of seeds of maize (cv Melkassa-2) and sorghum (cv Macia) harvested from plants after exposure to and recovery from pre- and post-flowering dehydration. The objectives of the study were to achieve a better understanding of 1) the effects of water deficit during the pre- and post-flowering stages on the seed viability and food (storage reserves) quality, and 2) the effects of dehydration and rehydration cycles at critical growth stages on subsequent seed performance and production, which could lead to the development of cultivars more able to efficiently partition assimilates to the reproductive organs in the field. The experiment was conducted in a controlled environment growth chamber under constant environmental conditions (12/12 h day/night, 28–32/17°C day/night temperature, 60–80% RH and 1200–1400 μmol m −2 s −1 PPDF). The seed viability and vigour tests were done on air-dried seeds and the seed quality analysis on freeze-dried seeds of both species.The results of the standard germination test indicated that sorghum seeds harvested after both pre- and post-flowering dehydration were not affected by the treatment, while maize seeds had reduced % germination. Sorghum seeds harvested after post-flowering dehydration had significantly decreased vigour after accelerated ageing. Dehydration during both the pre- and post-flowering stages resulted in reduced contents of protein, lipid and soluble carbohydrates (sucrose, glucose and fructose) in both species as compared to the control seeds. The species differed in the extent to which these reserves were reduced.