Experiments with ethylene-insensitive tomato (Lycopersicon esculentum) and petunia (Petunia x hybrida) plants were conducted to determine if normal or adventitious root formation is affected by ethylene insensitivity. Ethylene-insensitive Never ripe (NR) tomato plants produced more below-ground root mass but fewer above-ground adventitious roots than wild-type Pearson plants. Applied auxin (indole-3-butyric acid) increased adventitious root formation on vegetative stem cuttings of wild-type plants but had little or no effect on rooting of NR plants. Reduced adventitious root formation was also observed in ethylene-insensitive transgenic petunia plants. Applied 1-aminocyclopropane-1-carboxylic acid increased adventitious root formation on vegetative stem cuttings from NR and wild-type plants, but NR cuttings produced fewer adventitious roots than wild-type cuttings. These data suggest that the promotive effect of auxin on adventitious rooting is influenced by ethylene responsiveness. Seedling root growth of tomato in response to mechanical impedance was also influenced by ethylene sensitivity. Ninety-six percent of wild-type seedlings germinated and grown on sand for 7 d grew normal roots into the medium, whereas 47% of NR seedlings displayed elongated tap-roots, shortened hypocotyls, and did not penetrate the medium. These data indicate that ethylene has a critical role in various responses of roots to environmental stimuli.
Increased need for salt tolerant turfgrasses continues due to increased restrictions on water resources and to salt water intrusion into ground water. This is especially critical along coastal areas. Bermudagrass (Cynodon spp.) cultivars are widely used throughout the South on golf courses, home lawns, and sports turf facilities. Information on tolerance of warm‐season turfgrass cultivars to salinity is limited. The purpose of these studies was to document the glasshouse response of eight bermudagrass cultivars to solution cultures differentially salinized with NaCl. Salt was added to a basic nutrient solution to provide five initial salinity levels ranging from 2.7 to 9.9 dS m−1, but no cultivar differences were found in duplicate studies. Overall, top growth decreased 22%, but root growth increased 270% at the highest salt level. When salt levels ranged from 2.4 to 32.5 dS m−1 in a third study, cultivars differed in their response. ‘Tifdwarf’ and ‘Tifgreen’ were most tolerant while ‘common’ and ‘Ormond’ were most sensitive. Based on regression analyses within cultivars, Na increased and K decreased while total Na plus K in top growth was unaffected by salt concentration. Tissue levels of total Na plus K differed among cultivars.
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