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Abstract
Alstroemeria plants were grown under 10, 12, 14, 16, 18, and 24 hour photoperiods by employing an 8-hour natural day and low intensity incandescent lighting as a daylength extension. The production of flower stems was increased to a maximal level by extending the photoperiod to 16 hours in ‘Orchid’ and in ‘Regina’. Under 16 hours high-intensity supplementary lighting with high-pressure sodium (HPS) lamps, the production of flower stems in ‘Orchid’ increased by 49% in the first year and 36% in the 2nd year. ‘Regina’ flower stems increased by 26% in the first year and 16% in the 2nd year. HPS lighting increased the number of flowering shoots per square meter from 166 (control) to 262 in ‘Orchid’ and from 10 to 21 in ‘Regina’ during the period November to February.
The wax-apple [Syzygium samarangense (Bl.) Merr. & Perry] is a vigorous tropical fruit tree species that has five to six growth flushes per year. One-year-old, root-bearing wax-apple trees were grown in different-sized containers filled with potting mixture to test if container volume restricts shoot and/or root growth and thereby lends itself to forcing culture. The trunk cross-sectional area (TCSA) at 15 cm above the soil was measured to assess vegetative growth. After 6 months, the TCSA had increased quadratically with container volume. At the end of the first and second year, leaf count, leaf area, leaf dry mass, stem dry mass, shoot dry mass, and root dry mass were positively correlated with container volume. However, the shoot: root ratios remained fairly constant among treatments during the experimental period. Thus, root restriction is an effective means of reducing shoot and root growth of the wax-apple.
A portable, nondispersive infrared (NDIR) gas analyzer was modified to measure the concentration of CO2 and water vapor in small gas samples. A 2-mL gas sample was taken from a series of sealed flasks partially filled with a saturated solution of chemicals known to produce various levels of relative humidity (RH). The modified NDIR instrument quantified water vapor content by its absorption at 2.59 μm. Peak height was displayed on a strip chart recorder and a standard curve constructed. At a specific temperature, the vapor pressure (VP) and vapor pressure difference (VPD) were calculated for sweet pepper (Capsicum annuum L., cv. Mazurka) fruit packed in trays that were covered with plastic films having several levels of perforations. Water loss from the fruit was highly correlated with VPD inside the packages. The modified NDIR instrument has an advantage over other instruments used to measure RH because it can rapidly and simultaneously determine the concentration of water vapor and CO2 in a single injection of a small gas sample.
Greenhouse-grown `Bison' and `Doria' peppers (Capsicum annuum L.) were harvested when mature green (MG) (>95% surface green) or ripe (>95% of surface red or yellow). Both cultivars responded similarly to temperature and neither exhibited chilling injury (CI), as indicated by surface pitting, after storage at 13C for 1 or 2 weeks. Ripe peppers showed no CI when held at 1C for 1 or 2 weeks, while MG peppers exhibited CI after these treatments. Exposing MG peppers to 1C for 3 days caused CI and stimulated C2H4 (12.3x) and CO2 production (2.5x). In contrast, a similar exposure of ripe peppers did not cause CI but stimulated C2H4 (6.5x) and CO2 production (1.4x). It seems that CO2 and C2H4 production was stimulated by exposure to 1C, not necessarily by CI development. Our data question the physiological significance of elevated CO2 and C2H4 production in CI development. The observed tolerance of ripe peppers to 1C suggests that ripe greenhouse-grown peppers can be stored at temperatures lower than those currently recommended for bell peppers.
Abstract
Dormancy of non-cooled Lilium longiflorum Thunb. cv. Ace bulbs was broken with GA3 (1000 ppm), while ABA (500 ppm) partially negated the effect of vernalization on dormancy breaking. Infusion of bulbs with GA3 or ABA had little effect on days to anthesis. Injections of GA3, GA4, or GA7 into shoots from non-cooled bulbs did not substitute for vernalization or affect days to anthesis. ABA injections into shoots from cooled bulbs partially negated the effect of vernalization and delayed anthesis. Injections of GA3 or GA7 into shoots from cooled bulbs decreased days to anthesis, while GA3, GA4 or GA7 increased plant height. ABA delayed anthesis and reduced stem elongation. The major effect of exogenous GA applications appears to stimulate bolting.
Abstract
Lilium longiflorum Thunb. cv. Nellie White shoots rapidly emerged and flowered when bulbs were given a 4.5°C/40 day treatment. However, GA levels in the bulbs did not increase during the 4.5°C/40 day cold storage, but increased afterwards in the greenhouse with a GA maximum 30 days past storage. ABA activity patterns were similar to GA. Bulbs first treated at 4.5°C/30 days and then followed by 21°C/30 days had higher GA activity and their shoots were slower to emerge and flower than those of bulbs first treated at 21°C/30 days then given 4.5°C/30 days. Bulbs from 4 harvest dates had greater GA activity in the inner scales while ABA activity was greater in the outer scales.
Abstract
Samples of sweet potatoes [Ipomoea batatas (L.) Lam.] grown in field trials during 4 seasons in 1981 and 1982 were analyzed for trypsin inhibitor levels and protein concentration. A significant positive correlation between trypsin inhibitor levels and protein concentration was found in each season and between trypsin inhibitor level and dry matter content in 3 of the seasons. Clones were identified which had less trypsin inhibitor activity than predicted by multiple linear regression.
Design modification of a particle inflow-type gun for particle bombardment significantly simplifies construction and reduces fabrication time. The gun consists of a high-speed electric solenoid valve mounted on and through a vacuum jar. DNA-coated tungsten particles are placed on the support grid of a filter housing and accellerated by a burst of pressurized helium, which is controlled by a timer. Specimens are held between plastic screens and their distance from the particle support grid is adjusted with a miniature laboratory apparatus positioner. Transient expression of GUS in cantaloupe cotyledons and grape somatic embryos was equivalent to that obtained with a conventional particle inflow gun. The device was constructed with locally-available hardware in 40 minutes using a hand drill, some thread taps and a thread die.
Abstract
A drip-irrigation study was conducted at the Asian Vegetable Research and Development Center (AVRDC) to determine its effectiveness on yield and quality of tomato (Lycopersicon esculentum Mill.). Four drip-irrigation treatments, with moisture levels maintained above 25, 50, 65, and 80% available water, produced 20% to 40% more marketable yield than the treatment with monthly furrow irrigation, and 80% more than the nonirrigated control. Plots with 25% available water produced fewer nonmarketable fruits with similar yields to other drip-irrigation treatments and required 30% less water than the furrow irrigation control. Electrical conductivity of the root-zone soil extracts was lower for drip-irrigation treatments than for the furrow-irrigated plot. Leaf chloride content during the growing stages was not significantly different among various drip-irrigation treatments but was less than the furrow-irrigation treatment. No differences in fruit quality were measured between treatments.
Abstract
Leaf morphology of Pistacia atlantica Desf., P. chinensis Bunge, P. integerrima Stewart, P. khinjuk Stocks, P. lentiscus L., P. mexicana HBK, P. mutica F.&P., P. vera L., and P. weinmannifolia Poisson were compared. P. lentiscus, P. mexicana, and P. weinmannifolia were hypostomatic while the other species were amphistomatic. Leaves of P. vera, which are oriented randomly, appeared to be isolateral, while leaves of the other species are dorsiventral and are oriented horizontally. Differences in the length and density of the ab- and adaxial palisade cells and in the shape of the spongy parenchyma cells were noted among species. In an effort to relate structure to function, the daily patterns of carbon dioxide assimilation rate, A, and leaflet conductance, g, to water vapor among P. atlantica, P. integerrima, and P. vera were determined under field conditions. The mean maximum Pn rates were 2.1, 1.0, and 2.0 nmol CO2 cm−2 s−1, respectively.