Auxin deficiency at the onset on root growth in Allium cepa
Summary3-Indolylacetic acid (IAA) increased the length of the epidermis cells of onion roots during the initial stage of root growth, when cell length has not yet reached its maximum value, by up to 50% (10−11 M), while in the later, steady-state or dynamic equilibrium stage no promotive effects were present. It is suggested that the lesser elongation capacity of the cells at the onset of root growth is related to a deficiency in auxin while the steady-state phase is characterized by hormonal balance.
Transport of indoleacetic acid in intact roots of Phaseolus coccineus
SummaryIndoleacetic acid (IAA)-5-3H (2×10-9) was applied to intact roots of Phaseolus coccineus seedlings at the apex or 2 cm above the apex, and the movement of IAA-3H and its metabolites traced by sectioning and chromatography. Basipetal movement of label occurred for 2 cm or less, declining exponentially, and the amount increased with time. Acropetal transport from above the apex showed quantitatively less movement of radioactivity. After a 6h treatment period a decline of label occurred in the first 0.5cm, below which there was a long distance movement of small amounts of label, mainly in IAA, towards the apex where the label concentrated by a factor of approximately 2. Short-distance basipetal movement consisted of about equal amounts of IAA and metabolites, and only metabolites were found in areas more basipetal than 2cm. Label from solutions of sucrose-14C and 3H2O followed the same general pattern of movement as label from IAA-3H, except that acropetal movement of water showed a steady decrease in the amount of label as the distance from the area of application increased. The short distance basipetal transport of label with the breakdown of IAA-3H indicates that the extent of basipetal movement was limited by catabolic processes. The acropetal pattern of IAA-3H movement with the concentration of the transported material close to the apex, is possibly the result of transport in the phloem.
Thermal properties of the Florida Current as related to Ocean Thermal Energy Conversion (OTEC)
The thermal properties of the Florida Current are presented and analyzed for the available ocean thermal energy. For a cold water intake depth equal to or greater than 600 m, potential sites for Ocean Thermal Energy Conversion (OTEC) power plants appear to exist in the Straits of Florida and, to a lesser extent, off the coasts of Georgia and South Carolina. The maximum thermal differences occur on the continental shelf because of the geostrophic motion of the Gulf Stream. An estimate of the total available ocean thermal energy from the Florida Current, delivered in the form of electricity, is 3.5 × 1012 kWh yr−1. For a cold water suction depth of 600 m or more, seasonal variability in the ocean thermal resource is approx. ±35 per cent of average annual output.