Archived
This content is available here strictly for research, reference, and/or recordkeeping and as such it may not be fully accessible. If you work or study at University of Kentucky and would like to request an accessible version, please use the SensusAccess Document Converter.
Publication Date
1981
Description
Effects of variation in temperature, soil moisture supply, and illuminance on seed dormancy and seed formation of Srylosanthes hamata cv. Verano were studied. Plants were grown in the open in successive seasons, in controlled-temperature cabinets, and in the greenhouse where shading and watering treatments were varied after the onset of flowering. Hardseededness was strongly developed and was positively related to temperature during seed formation. After seed maturation, seed moisture content was the main factor governing hardseededness, and this quality was negatively associated with temperature during seed formation. High levels of hardseededness developed in all seeds when seed moisture content was below approximately 7 % , but the equilibrium moisture content of seeds stored in atmospheres of varying relative humidity was modified by temperature during seed formation. This fact helps to explain variation in hardseededness related to differing provenances of seedlots. Seeds formed under high temperature had higher content oflignin (which was concentrated in the counter-palisade cells) and of hemicellulose, lower content of cellulose, and shorter palisade cells; cutin content was independent of temperature. The seedcoat of hard seeds exhibited a more regular and organized structure and a more evenly recticulated surface than that of soft seeds. Seed color changed from dark to light as temperature of seed formation decreased from 27°C to 21 °C, but hardseededness was found to be unrelated to seed color per se. Embryo dormancy was transitory, and little developed. An inhibitor in the pod or testa restricted germination; this effect was independent of climatic conditions during seed formation and decreased after 120 days of seed storage. Dormancy was more strongly developed in the hooked upper articulation than in the hookless lower articulation. Short durations of soil moisture stress that reduced leaf water potential to minimum values of about - 25 to - 28 bars, and shading treatments that reduced radiation to about 20% of full daylight reduced seed production, but hardseededness was not consistently related to these treatments. Time of blooming, rate of floret appearance, total floret differentiation, duration of flowering, floret abortion, lower articulation formation, and time to pod maturity were sensitive to temperature conditions. Seed yield was maximal at 31 °/24°C. S. hamata cv. Verano is a short-lived plant, and persistence of sustained yields depends upon continual plant replacement from soil seed reserves. The levels of seed production and ofhardseededness are increased by warm conditions during flowering, and this factor favors and may even restrict its adaptation to dry tropical environments.
Citation
Argel, P J. and Humphreys, L R., "Climatic Influences During Flowering on Seed Dormancy and Seed Formation of Stylosanthes hamata cv. Verano" (1981). IGC Proceedings (1981-2023). 3.
(URL: https://uknowledge.uky.edu/igc/1981/section6/3)
Archival?
Archival
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Climatic Influences During Flowering on Seed Dormancy and Seed Formation of Stylosanthes hamata cv. Verano
Effects of variation in temperature, soil moisture supply, and illuminance on seed dormancy and seed formation of Srylosanthes hamata cv. Verano were studied. Plants were grown in the open in successive seasons, in controlled-temperature cabinets, and in the greenhouse where shading and watering treatments were varied after the onset of flowering. Hardseededness was strongly developed and was positively related to temperature during seed formation. After seed maturation, seed moisture content was the main factor governing hardseededness, and this quality was negatively associated with temperature during seed formation. High levels of hardseededness developed in all seeds when seed moisture content was below approximately 7 % , but the equilibrium moisture content of seeds stored in atmospheres of varying relative humidity was modified by temperature during seed formation. This fact helps to explain variation in hardseededness related to differing provenances of seedlots. Seeds formed under high temperature had higher content oflignin (which was concentrated in the counter-palisade cells) and of hemicellulose, lower content of cellulose, and shorter palisade cells; cutin content was independent of temperature. The seedcoat of hard seeds exhibited a more regular and organized structure and a more evenly recticulated surface than that of soft seeds. Seed color changed from dark to light as temperature of seed formation decreased from 27°C to 21 °C, but hardseededness was found to be unrelated to seed color per se. Embryo dormancy was transitory, and little developed. An inhibitor in the pod or testa restricted germination; this effect was independent of climatic conditions during seed formation and decreased after 120 days of seed storage. Dormancy was more strongly developed in the hooked upper articulation than in the hookless lower articulation. Short durations of soil moisture stress that reduced leaf water potential to minimum values of about - 25 to - 28 bars, and shading treatments that reduced radiation to about 20% of full daylight reduced seed production, but hardseededness was not consistently related to these treatments. Time of blooming, rate of floret appearance, total floret differentiation, duration of flowering, floret abortion, lower articulation formation, and time to pod maturity were sensitive to temperature conditions. Seed yield was maximal at 31 °/24°C. S. hamata cv. Verano is a short-lived plant, and persistence of sustained yields depends upon continual plant replacement from soil seed reserves. The levels of seed production and ofhardseededness are increased by warm conditions during flowering, and this factor favors and may even restrict its adaptation to dry tropical environments.
