Search Results
Abstract
Injecting CO2 gas into mist water (CO2 mist) promoted rooting of Ilex aquifolium L. ‘Silver Variegated Standard’ stem cuttings in spring propagation while inhibiting rooting in the fall. Supplementary lighting from high pressure sodium lamps (HPS) for 16 hr daily had similar effects as CO2 mist in the spring and inhibited root growth in fall propagation. There was a positive interaction between CO2 mist and HPS in spring propagation, suggesting that the promotive effects of these variables were due to enhanced photosynthesis.
Abstract
Clematis × ‘Jackmanii’ (C. lanuginosa × C. viticella × C. × eriostemon) and Clematis × ‘Comtesse de Bouchard’ (cultivar of C. × ‘Jackmanii’) were evaluated for winter flowering with supplementary lighting treatments combining two photoperiods and two levels of irradiance during September to January. The dormancy of ‘Jackmanii’ was overcome by long (16 hr) days or by high (HPS) irradiance during natural photoperiods (8.5-12 hr); the dormancy of ‘Comtesse de Bouchard’ was overcome only by long days, irradiance having no effect. Terminal flower bud formation was affected similarly by supplementary lighting. The development of lateral flower buds of both cultivars was greatly enhanced by combining long photoperiods and high irradiance.
Abstract
Cut flower Gerbera (Gerbera jamesonii Bolus) plants were grown in pots or ground benches under various photoperiods, levels of irradiance, and soil temperatures. Photoperiodic flowering response varied with the 3 cultivars; ‘Appelbloesem’ was not sensitive to photoperiod; ‘Oranje Nasau’ and ‘Fabiola’ were promoted by short day (SD). In pot-grown Gerbera, SD increased the number of flowers (inflorescences) per plant of ‘Oranje Nassau’ and ‘Fabiola’ in the summer-fall and fall-winter. Supplementary lighting with high-pressure sodium (HPS) lamps increased the fall-winter production of all 3 cultivars. Plants grown under 16 hr photoperiod by extending natural day length with incandescent light (INC) produced the least flowers per plant in both summer-fall and fall-winter. In bench-grown Gerbera, supplementary HPS increased the number of flowers during the fall-winter as compared to natural daylight (ND). Soil warming from 16°−20° to 23°C had no effect on productivity, but increased the peduncle length.
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.
Abstract
Pea cultivars may be severely or mildly affected (susceptible), or completely symptomless (resistant) when infected with an Oregon isolate of PSV. Infected plants of susceptible and resistant cultivars contained substantial virus concentrations which were not consistently related to symptom severity. The severity of symptoms in inoculated plants and the numbers of plants showing symptoms differed in various tests, apparently in response to changes in environment and the virulence of the virus. When apparent maximum symptom expression occurred, it was shown that the highest degree of resistance was due to a single recessive gene. Deviations from the expected ratio of 3 susceptible: 1 resistant (symptomless) were always the result of excess symptomless plants, probably because of combinations of effects of the environment, modifying genes from one or both parents, and in the later phases of the study, a reduced virus virulence. Observations and limited tests suggested that symptom development was promoted by conditions which were unfavorable for optimum plant growth.
Abstract
Plantlets orginating from adventitious buds of explants obtained from the decapitated shoot apex of a banana sucker established well under field conditions and gave rise to mature plants with uniform growth and normal yield of fruit. A total of one million pathogen-free plantlets for commercial planting was produced in 1983. Introduction of plantlets for commercial planting prevents the spreading of fusarial wilt of banana by planting materials to the disease-free orchards.
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.
Abstract
Comparative anatomical studies of vegetative buds from normal and failure prone (BF) ‘Nonpareil’ almond showed no anatomical difference in the buds, except reduced size in buds on severely affected BF trees, until early August to mid-September. The sequence of microscopically visible degenerative processes in shoot apices of BF trees is: l) breakdown of the outer tunica layer, 2) disorganized proliferation of the corpus: and, 3) the differentiation of layers of cells in the sub-apical region delimiting the potentially necrotic tissues of the apex. Subsequent abscission of affected buds occurs depending upon the extent of the necrosis. Growth was observed from 13% of buds from BF trees budded onto peach seedling rootstock, 38% of buds from non-BF trees grafted at the same time, and 95% of buds from normal plants. The scion buds had been collected and grafted in October, when internal anatomical symptoms were apparent. In general, the number of failing buds and the severity of the internal symptoms increased acropetally. Buds from BF trees attained maximum size by early June and thereafter decreased in size due to dessication.
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.
Inheritance of red flower color was investigated in crosses using Lamprecht's lines M0169 and M0056, which are derived from Phaseolus coccineus L., and Univ. of Florida P. vulgaris L. breeding line 5-593. Based on segregation in the F2populations from 5-593 × M0169 and 5-593 × M0056, we hypothesize that the genotypes for flower colors are sal/sal V/V for 5-593 and Sal/Sal v/v for M0169 and M0056. The backcross 5-593 × F, (5-593 × M0056) segregated for four flower colors in about equal frequencies, and F2, F3, and F4progeny tests of the backcross plants provided confirmation of all the genotypes in the digenic model. The two recombinant true-breeding colors/genotypes were white (sal/sal v/v) and china rose (Sal/Sal V/V). We hypothesize that the large deficiency of plants carrying the Sal allele in segregating populations is due to a gametophyte factor linked to Sal. We propose the gene symbol Ga for the gametophyte factor locus, which achieves complete selection for pollen carrying Ga on female plants carrying Ga, i.e., no pollen carrying ga achieves fertilization. The linkage between Ga and the marker locus Sal is 17 CM (centiMorgan).