Tomato plants (Lycopersicon esculentum Mill.) were grown in the greenhouse and in the field during 1979 and 1980. The inflorescences were treated with gibberellin (GA4/7) and/or benzyladenine (BA). Root exudate was collected at various stages of growth and development for the estimation of the levels of cytokinins in the plant. Soluble sugars and starch were determined in inflorescences at different stages of development. Partitioning of dry matter between the different plant portions was studied to evaluate growth of tomato plants in two different conditions. The application of GA4/7 and BA to tomato inflorescences promoted the development and increased the number of flowers. These growth regulators substantially increased fruit set and yield of tomatoes in both greehouse and field experiments. Determinations of carbohydrates in inflorescences treated with growth regulators showed higher amounts of soluble sugars and starch over a considerable period of development. The level of cytokinins in root exudate was higher during early phase of vegetative growth. At the time of bud formation and anthesis, the level of cytokinins declined. The quantity of translocated cytokinins in the greenhouse was 4 to 5 times higher than under high temperatures in the field. The low levels of cytokinins were associated with poor flower development. Field grown tomato plants produced more vegetative growth and fewer inflorescences than plants in the greenhouse. Allocation of assimilates to newly developed leaves and low level of growth regulators in buds and inflorescences might contribute towards more vegetative growth but poor flowering under high temperatures.

No description available.

Effects of growth environment (E) on carbon isotope discrimination (Delta), water-use efficiency (WUE), leaf movement (LM) and nutrition of bush bean were examined. Environments in greenhouse (GR), open air (E0), perforated (E1) and non-perforated (E2) plastic covers in combination with well-watered (W0), moderately-watered (W 1), and water-stressed (W2) plants were used. Soil water content (WC), E, and E x WC interaction significantly affected Delta, WUE, dry matter (DM) and water use. WUE, photosynthetic rate, and leaf nitrogen increased; while Delta, DM, and transpiration decreased with water stress in GR, and E0. WUE in E2 either decreased or remained almost constant with decrease of WC. WUE of W0, and Delta in E2 were independent of growing environment, and WC, respectively. WUE and Delta correlations were significant in GR, E0, and E 1. LM was more paraheliotropic inside plastic coverings than those in E0. LM and pulvinus water content were affected by WC and temperature. High correlations were found between LM and the transmission of beta-rays from a beta-ray gauging system, WC, and leaf water potential. A high correlation was also found between leaf angle and 45Ca activity ratio between the extensor and flexor parts of the pulvinus. 32P uptake increased with increased root temperature, and decreased in presence of iron in the medium. Q10 values showed 32P uptake with and without the presence of iron to be mostly diffusion-controlled, but leaf movements were active processes requiring the expenditure of energy.

No description available.

No description available.

Ultraviolet (UV) radiation damages both eukaryotic and prokaryotic cells by causing the formation of free radicals which damage cell membranes and DNA. Antioxidant vitamins have been shown to protect cells from UV-induced damage by scavenging free radicals. The protection of skin and its normal flora is necessary for the health of individuals in resisting diseases caused by microorganisms and delaying the long-term damage caused by UV radiation.This research investigated the effects of the antioxidants vitamin A and ascorbic acid, as well as UV-irradiation on both prokaryotic (Staphylococcus epidermidis) cells and eukaryotic (human fibroblast skin) cells. This information is important in determining the effects of vitamin treatment on skin and its normal flora.Results indicate that ascorbic acid is rapidly (within six hours) degraded after being dissolved in water or medium. Treatment of cells with ascorbic acid must take into account this rapid degradation. S.epidermidis cells were protected from UV-induced damage by treatment with ascorbic acid but were more sensitive to UV-irradiation when treated with vitamin A. Human fibroblast cells treated with ascorbic acid did not exhibit morphological changes when compared to untreated cells. / Department of Biology

Whole body vibration (WBV) is a technique that has been shown to induce positive blood flow changes, however little is known about the effect of different vibration amplitudes on arterial blood flow. Purpose. The purpose of this study was to determine the effect of 2 different amplitudes during an acute bout of WBV on blood flow through the popliteal artery. Methods. Thirty healthy, recreationally active subjects (15 women, 15 men) aged 19-34 years performed two, 10 - minute bouts of vibration at a frequency of 30 Hz and high amplitude (6 mm) or low amplitude (3 mm) in random order after a period of prone rest. Doppler ultrasound was used to assess changes in blood flow. Mean blood flow velocity, peak velocity, end-diastolic velocity, pulsatility index, and resistive index measures were taken immediately before vibration and immediately after. Results. Mean blood flow velocity increased after 10 minutes of WBV. Mean velocity increased more in the 6mm trial (pre= 21.6 ± 4.74 cm/s, post= 25.3 ± 6.11 cm/s) than in the 3mm trial (pre= 22.3 ± 4.33 cm/s, post= 23.5 ± 5.94 cm/s). Peak blood flow velocity increased following 10 minutes of WBV and increased more in the 6mm trial (pre= 37.1 ± 9.78 cm/s, post= 43.7 ± 10.95 cm/s) than in the 3mm trial (pre= 37.8 ± 8.92 cm/s, post= 39.4 ± 10.5 cm/s) following 10 minutes of passive WBV. Pulsatility index also increased significantly following 10 minutes of WBV and increased more in the 6mm trial (pre= 1.639 ± 0.1299, post= 1.729 ± 0.1324) than in the 3mm trial (pre= 1.660 ± 0.1219, post= 1.671 ± 0.1428). No main effects or interactions were observed for resistive index or end diastolic blood flow velocity (P>0.05). Conclusion. Ten minutes of passive WBV increases blood flow velocity. High amplitude (6 mm) produced a more pronounced increase in blood flow than the low amplitude (3 mm). Given the relationship between blood flow velocity and WBV, these results suggest that amplitude plays a role in increasing blood flow and that high amplitude (6 mm) may be more effective than low amplitude (3 mm) in improving circulation to the lower leg. / School of Physical Education, Sport, and Exercise Science

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1967. / Bibliography: leaves 145-152. / xiii, 152 l illus., tables

Thesis (MScAgric (Horticulture))--University of Stellenbosch, 2007. / The production of high quality fruit that meet international standards is of vital importance to the South African fruit industry. Detrimental climatic conditions are forcing producers to examine alternate production methods. In this study the effect of protective netting on apple tree (Malus domestica) physiology, microclimate and fruit quality was investigated to determine the potential of apple production under netting in the Western Cape Province of South Africa. The influence of 20% black shade netting on the photosynthetically photon flux density, leaf and fruit surface as well as air temperature was measured on four blush apple cultivars over a two year period in the Koue Bokkeveld area, in the Western Cape, South Africa. Measurements were also taken on leaf gas exchange, including net CO2 assimilation rate under ambient and saturating CO2 conditions, stomatal conductance, and transpiration rate. A decrease in light conditions of 22 - 31% was measured under black netting thus reducing the amount of light available to the plant significantly. Leaves under the netting were cooler by 1.7 – 3.9°C on a milder day (11 January 2005) and by 4.3 – 6.2°C on a hot day (28 February 2005) than control leaves. Fruit surface temperature under the netting was cooler by 0.7 - 2.9°C on milder days, and by 4.0 - 5.3°C on a hot day (28 February 2005) than control fruit. Significant increases in CO2 assimilation, stomatal conductance and transpiration were found under the netting. Netted treatments also showed a lower leaf vapour pressure deficit and tended to be less water stressed having higher leaf water potential than the control treatments. Differences in leaf nitrogen were not significant between treatments except for ‘Cripps’ Pink’ where non netted treatments had higher leaf nitrogen levels than the netted treatments during the 2004 season. Heat tolerance and the ability to recover after exposure to different temperatures for different lengths of time, was evaluated for the same four blush apple cultivars grown under protective netting. The results showed that fruit taken from the netted treatments had a higher incidence of injury based on chlorophyll fluorescence measurements, and did not recover well at temperatures higher than 45°C. The higher tolerance of the non-netted fruit at 45°C could be due to better acclimation to high light and heat levels than the fruit from the netted treatment. Fruit quality of ‘Royal Gala’, ‘Fuji’, Cripps’ Pink’ and ‘Braeburn’ was evaluated for netted and non-netted treatments as well as between five different crop loads as sun-treatments. It was found that cultivars reacted differently to the altered microclimate under the netting. Significant interaction between net and crop load treatments was found for fruit mass of ‘Royal Gala’ and ‘Fuji’. Fruit mass declined more rapidly with increased crop load under nets than in the open. The net treatment reduced sunburn significantly in all the cultivars except ‘Cripps’ Pink’. Ground colour was found to be positively influenced by netting on ‘Braeburn’ and during 2005 on ‘Royal Gala’. Blush colour was reduced under the netting for ‘Braeburn’ and ‘Fuji’ and unaffected for ‘Royal Gala’ and ‘Cripps’ Pink’. Fruit firmness, total soluble solids and titratable acidity, were reduced under nets for most of the cultivars. Netting thus seems to have a positive effect in reducing sunburn damage but a varying effect on other fruit quality parameters, which seem to be cultivar specific. The influence of black protective netting on vegetative growth was determined by measuring total prunings and trunk circumference. Reproductive bud development analysis was also done. An increase was found in summer prunings for ‘Fuji’ and ‘Cripps’ Pink’ which was most likely due to the topping of the trees to prevent them from growing into the netting. Seasonal trunk growth was affected significantly for ‘Braeburn’ with a higher percentage recorded under the netting. Reproductive bud development was higher for the netted treatments and on trees with lower crop loads. Photosynthetic photon flux density was reduced significantly in a ‘Granny Smith’ orchard at harvest by black, blue and grey type netting. Sunburn was significantly reduced under the black and blue netting. Fruit mass was higher under the netted treatments during the second season of measurements. Firmness and total soluble solids were lower under the netting. Blush colour was found to be significantly lower under the black netting. Seed viability, ground colour, titratable acidity, starch breakdown, stem end russet and the occurrence of Fusicladium pyrorum damage was unaffected by the netting.

This study evaluated the effect of a macro- versus a microcooling system on the cognitive, psychomotor and physiological performance of human operators. Male subjects (n = 24) were acclimatized for four days and then subjected to three different environmental conditions: hot ambient (40°C; 40% RH), microcooling and macrocooling. Each environmental condition was repeated twice; once under a rest condition and once while simulating a physical workload of 40 W. Four performance tests (reasoning, eye-hand coordination, memory, reaction time) were conducted once every hour for four hours. Five physiological measurements, viz rectal temperature, skin temperature, heart rate, total sweat loss and sweat rate, were taken. A significant difference existed between the physiological responses under the hot ambient condition and both cooling conditions. For all five physiological parameters he human operator benefitted substantially whatever the cooling condition. The psychological performance results indicated a greater benefit under the cooling conditions, though various external factors may have influenced responses. User perception showed that macrocooling was perceived to be the optimal method of cooling. The results showed that there was no difference in the extent to which both rectal temperature and heart rate (for rest and work conditions) decreased over the 4-hour study period with micro- and macrocooling. In the baseline hot environment both increase. Sweat rate was lowest when resting or working in a microcooled environment and at its highest in the hot baseline environment. Mean skin temperature was lowest (for rest and work conditions) with microcooling and highest in the hot baseline environment. Reaction time and memory/attention were the same under all three environmental conditions. Eye-hand coordination was better with cooling than without, but did not differ between the two cooling conditions. Reasoning ability was poorest under the hot baseline condition and best in the macrocooled environment. User perception showed that the subjects found macrocooling highly acceptable. Microcooling was found to be uncomfortable, particularly because cold air (18 - 21°C) entered the jacket at one point which caused numbness of the skin at that point. Jackets did not always fit subjects well and the umbilical cord restricted free movement.