| The objectives of this study were (1) to determine whether applications of ethephon fusicoccin, kinetin, and thiourea, could promote Glaucium spp seed germination under different salinity levels; (2) to determine the most effective concentrations of each growth regulator in enhancing horned poppy seed germination under saline conditions; (3) to evaluate the degree of salinity tolerance among the common Horned Poppy species that were available from Denver Botanic Gardens, G. flavum, G. corniculatum, G. grandiflorum and G. acutidentatums ; (4) determine which evaluation criteria are most closely associated with superior salinity tolerance; (5) to confirm selection criteria for evaluation of salinity tolerance in Horned Poppy species and (6) to evaluate the degree of drought tolerance among the common Horned Poppy species, G. flavum, G. corniculatum , G. grandiflorum and G. acutidentatums. .;An application of ethephon, fusicoccin, kinetin and thiourea were evaluated for their relative ability to promote Glaucium spp seed germination under different salinity levels and to determine the most effective concentrations of each growth regulator in enhancing Glaucium spp germination under saline conditions.;The salinity tolerance of the four Horned Poppy species available from Denver Botanic Gardens, G. flavum, G. corniculatum, G. grandiflorum and G. acutidentatum, were compared to examine the effects of salinity, (EC = 5, 15 and 25 dS m-1), on plant characteristic that add up to its attractivrness, and to determine which tolerance mechanism was associated with superior salinity tolerance among the tested species after evaluating the effects of salinity on total nonstructural carbohydrate content (TNC), shoot reducing sugar content (RSC), Proline content and K+/Na+ in shoots of Glaucium spp. Lysimeter columns were used in this study which was replicated twice in the green house.;All 4 horned poppies were also evaluated for drought tolerance, ( G. flavum, G. corniculatum, G. grandiflorum and G. acutidentatums), by examination the effects of drought on plant aesthetics as well as the mechanisms associated with drought tolerance such as proline content, total non-structural carbohydrate content (TNC), shoot reducing sugar content (RSC) and Evapotranspiration rate (ET) as indicated by water use efficiency among the tested species. Lysimeter columns were used in this study which was replicated twice in the green house. Glaucium spp. were initiated from seeds. Seedlings were planted in potting mix, (Pro-Mix , Mycorrhizae and Biofunglcide). Fifty 3 leaf seedlings of each species were transplanted, each into PVS tubes (15 cm diameter and 50 cm long) containing commercial potting mix. The potting mix was mixed with sand in a 2:1 ratio to increase pore space. Water regimes applied included control (100% of the total evapotranspiration), as well as 75%, 50% and 25% of total evapotranspiration,(ET).;Ethephon was the most effective growth regulator in ameliorating salinity effect on Glaucium ssp seed germination followed by thiourea, fusicoccin, and kinetin. As salinity increased, Glaucium spp. exhibited reduction in leaf characteristics, plant height, flowering characteristics, overall plant quality (attractiveness), TNC, and K+/Na + ratio, and increased shoot total reducing sugars and proline content. G. flavum showed greater salinity tolerance at all salinity levels when compared to the other tested species. Proline accumulation could add to the salinity tolerance through osmoregulation or by acting as a carbon and nitrogen sink for stress recovery. Similarly, as drought increased, Glaucium spp. exhibited reduction in leaf characteristics, plant height, flowering characteristics, overall plant quality (attractiveness), TNC, and ET rate, and increased shoot total reducing sugars and proline content. G. flavum again showed greater tolerance at all water regimes ( 100%,75%,50% and 25% ET) when compared to the other tested species. Also, Proline accumulation was correlated with drought tolerance that could be done through osmoregulation or by acting as carbon and nitrogen sink for stress recovery. (Abstract shortened by UMI.). |
