Search Results

You are looking at 1 - 10 of 19 items for :

  • Author or Editor: Robert E. Paull x
  • HortScience x
Clear All Modify Search
Author:

There is a need to develop effective, non-damaging, non-polluting, non-carcinogenic procedures for insect disinfestation and disease control in fresh horticultural products. The loss of ethylene dibromide as a fumigant and the uncertainties of other fumigants, has meant that alternatives are needed. The most likely possibilities include irradiation, heat, cold and controlled atmospheres. Irradiation doses required for sterilization of insects cause only minor physiological changes, while controlled atmospheres appear to require longer periods of exposure than the postharvest life of most tropical fruit. The sensitivity of tropical commodities to temperatures less than 10°C makes cold treatments inappropriate for most tropical commodities. Heat treatments seem to be most promising. For papaya, the requirement is that the fruit core temperature reach 47.2°C, this can occasionally disrupt fruit ripening. The sensitivity to heat is modified by seasonal, variety and rate of heating factors. The sensitivity can be related to the heat shock response and the presence of heat shock proteins.

Free access
Author:

Abstract

Rating scales and their descriptions are described for spadix condition, spathe discoloration, and gloss for anthurium inflorescence.

Open Access
Author:

Abstract

The optimum storage temperature for flowers of the ‘Kaumana’, ‘Nitta’, and ‘Ozaki’ cultivars of anthurium (Anthurium andraeanum Andre) was between 14° and 17°C. A AgNO3 pulse (4 mm, 40 min) given immediately after harvest increased postharvest life of stored flowers but had no effect on flowers that were placed immediately in the vase. Maximum postharvest life was achieved with Ag+ treated flowers packed for 3 days. It was possible to store packed, untreated flowers for 9 days and still have 2 weeks of postharvest life before spadix browning, spathe blueing, or loss of spathe gloss became objectionable.

Open Access

Four papaya (Carica papaya L.) lines that may have commercial value were surveyed for variability in ripening characteristics. Skin and flesh yellowing, fruit softening, respiration rate, and ethylene production were compared. Skin yellowing and flesh softening followed a similar sigmoid pattern for all lines. However, the temporal relationship between skin yellowing and flesh softening differed among the lines. Fruit from lines RL-1-3 and RL-1-12 did not begin to soften until the skin was 80% yellow, compared to 40% yellow for the commercial cultivars Kapoho and Sunrise. Fruit from RL-1-3 and RL-1-12 took 12 and 16 days, respectively, to reach 100% yellow from color break, which was two to three times as long as that of `Kapoho' and `Sunrise' at 22C. All lines showed typical climacteric respiration and ethylene patterns. The time between the start of skin yellowing and the rise in respiration varied from ≈2 days in `Kapoho' and `Sunrise' to ≈4 days in line RL-1-3 and 8 days in line RL-1-12. The respiratory peak was greatly reduced in RL-1-12. The patterns of softening in lines RL-1-3 and RL-1-12 differed from `Kapoho' and `Sunrise': RL-1-3 softened slowly, but reached similar firmness values to other lines 4 days after 100% yellow skin color; RL-1-12 had a much slower rate of softening and the fruit were still firm 4 days after the fruit reached 100% yellow. The ripening patterns of line RL-1-3 and RL-1-12 could be useful in postharvest handling and provide material for studying the genetic control of fruit softening.

Free access
Authors: and

This study examined the relationship between the activity of fruit enzymes involved in metabolizing sucrose and sugar accumulation during fruit development, to clarify the role of these key enzymes in sugar accumulation in papaya fruit. Papaya fruit (Carica papaya L. cv. Sunset) were harvested from 14 to 140 days after anthesis (DAA). Fruit dry matter persent, total soluble solids (TSS), and sugar composition and the activity of enzymes: sucrose phosphate synthetase (SPS), sucrose synthetase (SS), and acid invertase were measured. `Sunset' papaya matured 140 days after anthesis during the Hawaii summer season and in about 180 days in cool season on the same plant. Fruit flesh dry matter persent, TSS, and total sugar did not significantly increase until 30 days before harvest. Sucrose synthetase was very high 2 weeks post-anthesis, then decreased to less than one-third in 42 to 56 DAA, then remained relatively low during the rest of fruit development. Seven to 14 days before fruit maturation, SS increased about 30% at the same time as sucrose accumulation in the fruit. Acid invertase activity was very low in the young fruit and increased more than 10-fold 42 to 14 days before maturation. SPS activity remained very low throughout the fruit development and was about 40% higher in mature-green fruit. The potential roles of invertase and sucrose synthetase in sugar accumulation will be discussed.

Free access

Production of heat shock proteins (HSP) in response to high temperatures are a highly recognizable feature of plant and animal systems. It is thought that such proteins play a critical role in survival under supraoptimal temperature conditions. The use of heat treatments has been examined extensively, especially for disinfestation of fruit and disease control. Heat treatments can affect physiological responses, such as ethylene production, softening, and other ripening factors, as well as reducing physiological disorders, including chilling injury. HSPs have been implicated in a number of stress responses, but the extent that they are involved, especially in amelioration of chilling injury, is a subject of debate. In a number of cases, heat shock proteins do not appear to be involved, and HSPs do not explain long-term adaptation to heat; other systems for which we do not have models may be at work. Resolution of these issues may require the use of transgenic plants with modified heat shock responses.

Free access

Over ripe and abnormally soft fruits occur often during papaya shipments to the mainland U.S.A. Calcium fertilization to the soil did not always increased Ca concentration in the mesocarp. Calcium plus K treatment was more effective at increasing the Ca concentration in the mesocarp than Ca treatment alone. Calcium and K fertilization did not affect the fruit color development. There was a positive correlation between mesocarp Ca concentration and ripe fruit firmness, with no relationship between K or Mg concentration and ripe fruit firmness. Vacuum infiltration with CaCl2, MgCl2, KCl to mesocarp plugs in vitro showed that Ca significantly delayed softening and reduced C2H4 production, and that MgCl2 and KCl also slowed the softening. Use of the chelating agent sodium citrate increased the rate of softening, probably, by removing Ca from the cell wall. We conclude that Ca is an important factor in fruit firmness and that the increase of Mg and K by infiltration has different effects on fruit firmness from that by soil fertilization.

Free access

The Anthurium andraeanum `Kaumana' flower growth and development before and after emergence was studied. The process before emergence was long and slow. A tiny flower bud, about 0.3 cm long was formed 80 days before its emergence. The whole period before emergence was divided into three phases: cell division phase, slow growth phase and elongation phase. The characteristic of each phase was studied.

The leaf which bears the flower bud at its petiole base is called subtending leaf. Its growth had a significant influence on the flower bud growth at its petiole base. Detaching the young subtending leaf blade resulted in an earlier flower emergence.

Free access