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Under most circumstances, some type of storage, from ephemeral to long-term, is an asset in the marketing of horticultural products. However, attempts to transfer developed country (DC) storage technology to the less-developed countries (LDCs) can be futile unless two conditions are met: 1) There must be a prior extension program to introduce the concept of what produce storage involves and what benefits can be expected from its proper use; and 2) the storage techniques introduced must be appropriate for the area. In many circumstances it may be necessary to start with very simple “old-fashioned” methods. Stages of development in LDCs are described, together with suggestions as to appropriate storage methods for each stage and how to prepare for them.
Abstract
Humidity as related to horticulture is discussed in terms of: ways of expressing humidity levels; physical properties of water vapor; and temperature-humidity and air circulation-humidity interactions. The role of humidity in transpiration, killing freezes, and storage and transport of fruits and vegetables is discussed. Also given are sources of information on methods of recording and controlling humidity in postharvest applications.
Abstract
We all pay lip service to the concept that fruits and vegetables are alive. Nevertheless, very little attention is paid to what must be a major trauma for most of them, being suddenly cut off at harvest from the water supply that has hitherto sustained them. While on the plant, the organs that we call fruits and vegetables participated in a dynamic traffic in water due to transpiration and to withdrawal of water by the plant in times of stress (40). At harvest, this suddenly ceases and for water, as well as other essential nutrients, they have to become what Biale has called “self sufficient harvested fruit” (8). This transition is minimal for those that are storage organs physiologically prepared for a long resting period (e.g. onions, cabbage, pumpkins, beets, carrots, potatoes) or are fruits that form a complete abscission layer preparatory to inevitable dehiscence (e.g. nuts, apples, pears, persimmons, plums, pomegranates, lychees). The water relations transition is maximal for those severed from the parent plant regardless of botanical independence or physiological maturity (e.g. okra, cauliflower, asparagus, corn-on-the-cob, leeks, celery, green beans, parsley, lettuce, green peas). Fruits that have a long harvest period from a single bloom (oranges, grapefruit, avocado) are intermediate. At the time of the fruit’s sudden severance from a hitherto assured water supply, humidity (as distinct from root-supplied water) becomes of critical importance. The trauma of this onset of harvested life should be a consideration in the handling of horticultural products.
Abstract
Fumigation with 2-aminobutane (2-AB) provides effective and convenient decay control for citrus fruits, but the temporary residue tolerance of 20 ppm can easily be exceeded. Factors found to control residues were the cultivar, concentration of 2-AB, temperature, duration of fumigation, and load (as a percentage of maximum capacity) in the fumigation chamber. The simplest procedure was to evaporate the entire charge of 2-AB as rapidly as possible. Residues in ‘Dancy’ tangerines and ‘Temples’ were higher than in oranges. Safe dosages for waxed fruit in poly bags and master cartons fumigated for 3 hr in full cabinets at various temperatures were (in ml/100 cu ft): 80 ml at 85° F, 110 ml at 70°, and in excess of 150 ml at 50° and below. Risk of exceeding tolerance at 40° and lower was minimal. Use of a chlorinated hydrocarbon, Quick Color, to eliminate explosion hazard had no consistent effect upon 2-AB residues.
Abstract
‘Hamlin,’ ‘Pineapple,’ and ‘Valencia’ oranges and ‘Marsh’ grapefruit were harvested by hand and with either the limb clamp shaker, foliage (coil) shaker, or vacuum tube picker's aid. Harvesting trials were combined with tests of abscission sprays, pre- and postharvest fungicides, and simulated fresh fruit marketing. All mechanical shaker harvesting increased losses from cuts and punctures, but “plugging” was so reduced that percentage of sound fruit sometimes did not differ significantly from that in the hand picked controls. When mechanical harvesting was followed by the fungicide thiabendazole (TBZ) decay in ‘Hamlin’ oranges during simulated fresh fruit marketing was not significantly higher than in the hand harvested controls treated with diphenyl only. Mechanically harvested fruit from trees sprayed with benomyl (Benlate) always had less decay than hand harvested fruit without the benomyl spray, differences usually being significant. Abscission sprays were helpful only for crops intended for cannery use. Long stems on mechanically harvested fruit remain a problem.
Abstract
Resistance of grapefruit (Citrus paradisi Macf.) to chilling injury (CI) was compared with the concentration of reducing sugars in the peel through 3 harvesting seasons. Accumulation of reducing sugars preceded increased resistance to CI. The increase in reducing sugar concentration at mid-season (December – February) resulted from the hydrolysis of sucrose which is regulated by temperature. Accumulation of reducing sugars may be prerequisite to increased resistance of grapefruit to CI, but the role(s) of reducing sugars in the resistance mechanism has not been determined.
Abstract
Mechanical harvesting has, of course, long been standard for many annual crops, the “combine harvester” for wheat being an early, and successful, example. In some instances (e.g., tomato, plant breeders have “tailor made” cultivars to adapt them to mechanical harvesting. Typically, such annuals are destroyed in harvesting. The plant must be preserved with perennial crops, although sometimes considerable injury to the plant can be acceptable when (as for grapes or raspberries) the plant is severely pruned annually. Substantial damage to the plant (tree) is not acceptable, in mechanical harvesting of tree crops, but leaf damage is of minor consequence for deciduous tree crops, and the fruit is biologically destined to abscise; if it is not harvested. Damage to the product is not a problem, it will soon fall naturally for some deciduous tree crops (particularly nuts of various kinds). In contrast, mechanical harvesting of citrus fruits involves quite extraordinary problems. The tree is evergreen and substantial leaf damage is not acceptable. The fruit has no clearly defined abscission period. The same grapefruit that might be picked in October can hang on the tree until May. Citrus fruits are extremely subject to decay. ‘Valencia’ (an important cannery orange cultivar) takes 12 to 18 months from bloom to acceptable maturity to complicate matters further. Thus, there are 2 crops on the tree at harvest time; mature fruit that are to be harvested and immature fruit that must not be damaged or removed. It is apparent after 20 years and millions of dollars spent in Florida that the problem (particularly for ‘Valencia’) is as much biological as it is mechanical. The fruit, but not the leaves, must be made to abscise and, for ‘Valencia’, the tree must retain the immature crop while releasing the mature fruit.
Abstract
Resistance of ‘Marsh’ grapefruit (Citrus paradisi Macf.) to chilling injury (CI) at 4.4°C was highest during February–March, 1978 in Florida, Reducing sugar levels correlated better with resistance to CI than did total soluble carbohydrates or peel color. High levels of reducing sugars in grapefruit peel are considered to indicate greater resistance to CI and reducing sugars possibly play a significant role in promoting CI resistance of grapefruit peel at midseason (February–March in Florida).
Abstract
Changes in susceptibility to chilling injury of grapefruit (Citrus paradisi MacF.) were found to vary directly with the growth activity of the trees. Exogenous growth regulators were applied to test the hypothesis that they may be involved in seasonal variations in susceptibility to chilling injury. Benzyladenine, gibberellic acid and 2,4-dichlorophenoxyacetic acid applied postharvest and benzyladenine and 2,4-D applied preharvest significantly altered susceptibility to chilling injury although the direction and extent of the changes were neither consistent nor predictable.