Abstract
Some naphthalene and phenoxy compounds prevent preharvest drop of apples, pears, and citrus fruits. These studies have been complicated by an unrecognized high level of ethylene produced by leaves and fruit on trees sprayed with these growth regulators. An apparent contradiction is the effectiveness of both 2,4-dichlorophenoxyacetic acid and n-dimethylaminosuccinamic acid (a growth retardant which retards biosynthesis of auxin) in preventing abscission of apples. Thus, in the presence of low auxin concentrations in the tissue, this growth retardant prevents fruit abscission even more effectively than 2,4-dichlorophenoxyacetic acid at high auxin concentrations in the tissue. This anomaly is clarified on the basis that n-dimethylaminosuccinamic acid, in the presence of a known low ethylene biosynthesis, delays maturity of the fruit and thus prevents fruit abscission. On the other hand, 2,4-dichlorophenoxyacetic acid prevents abscission by direct growth hormone action, in spite of the side effects of ethylene production which speeds ripening of the fruit. With the promotion of abscission of leaves and fruit of agricultural crops, attention is given to the use of chemicals which induce ethylene production when applied to the plant, but which have no growth promotion effect to retard abscission. We can distinguish 5 kinds of such chemicals. One group includes gibberellic and abscisic acids that induce treated leaves to produce ethylene and abscise (under certain circumstances). However, they do not induce ethylene production by fruit and do not promote fruit abscission. A second group includes ascorbic acid, which, when used at relatively high levels, induces fruit to produce enough ethylene to promote abscission. Ascorbic acid-treated leaves also produce ethylene but not enough to cause much defoliation. A third group includes protein-synthesis inhibitors, such as cycloheximide. When low concentrations (about 30 mumoles/l) are sprayed on the fruit, the rapid effect of the freely moving ethylene (produced by the treated fruit) appears to mask temporarily any potential effect of the slowly moving inhibitor. A fourth group includes 2-chloroethylphosphonic and cupric ethylenediaminetetracetic acids, which induce ethylene production of fruit and leaves; production by leaves is substantially greater than by fruit and substantial defoliation results. A fifth group includes the cotton defoliation chemicals which clearly produce ethylene primarily as a result of chemical injury to the leaf blade. Another group of compounds, represented by beta-hydroxyethylhydrazine, produces ethylene by a chemical reaction with formaldehyde and water, and the presence of leaves or fruit is not required. At this time we are unaware of how chemicals in groups one to four act to promote ethylene evolution in leaves and fruit, but possible biological and chemical paths of ethylene production are discussed.
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Claims 6
Claim · model-written summary
Some naphthalene and phenoxy compounds prevent preharvest drop of apples, pears and citrus fruits.
- Taxon
- apples, pears, and citrus fruits
Citrus
Malus domestica
Pyruse0 - Treatment
- Some naphthalene and phenoxy compoundse0
- Outcome
- preharvest drope0
- Direction
- prevente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Some naphthalene and phenoxy compounds prevent preharvest drop of apples, pears, and citrus fruits”
Claim · model-written summary
n-dimethylaminosuccinamic acid prevented apple fruit abscission even more effectively than 2,4-dichlorophenoxyacetic acid at high auxin concentrations.
- Taxon
- applesMalus domesticae7
- Treatment
- growth retardante1
- Outcome
- fruit abscissione1
- Direction
- even more effectivelye1
- Comparator
- 2,4-dichlorophenoxyacetic acide1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“this growth retardant prevents fruit abscission even more effectively than 2,4-dichlorophenoxyacetic acid at high auxin concentrations in the tissue”
e7“An apparent contradiction is the effectiveness of both 2,4-dichlorophenoxyacetic acid and n-dimethylaminosuccinamic acid (a growth retardant which retards biosynthesis of auxin) in preventing abscission of apples”
Claim · model-written summary
Gibberellic and abscisic acids induced ethylene in treated leaves but not ethylene production by fruit.
- Taxon
- agricultural cropst0
- Treatment
- gibberellic and abscisic acidse3
- Outcome
- ethylene production by fruite4
- Direction
- do not inducee4
Not reportedComparator
Verbatim
t0“agricultural crops”
e3“One group includes gibberellic and abscisic acids that induce treated leaves to produce ethylene and abscise (under certain circumstances)”
e4“However, they do not induce ethylene production by fruit and do not promote fruit abscission”
Claim · model-written summary
Ascorbic acid used at relatively high levels induced fruit to produce enough ethylene to promote abscission.
- Taxon
- agricultural cropst0
- Treatment
- ascorbic acide4
- Outcome
- abscissione4
- Direction
- promotee4
- Qualifier
- when used at relatively high levelse4
Not reportedComparator
Verbatim
t0“agricultural crops”
e4“A second group includes ascorbic acid, which, when used at relatively high levels, induces fruit to produce enough ethylene to promote abscission”
Claim · model-written summary
2-chloroethylphosphonic and cupric EDTA acids induced ethylene production by leaves that was substantially greater than by fruit, causing substantial defoliation.
Verbatim
t0“agricultural crops”
e5“A fourth group includes 2-chloroethylphosphonic and cupric ethylenediaminetetracetic acids, which induce ethylene production of fruit and leaves; production by leaves is substantially greater than by fruit and substantial defoliation results”
Claim · model-written summary
beta-hydroxyethylhydrazine produces ethylene through a chemical reaction with formaldehyde and water, without needing leaves or fruit.
Verbatim
t0“agricultural crops”
e6“Another group of compounds, represented by beta-hydroxyethylhydrazine, produces ethylene by a chemical reaction with formaldehyde and water, and the presence of leaves or fruit is not required”
The same questions in other papers
class · yield · Malus domestica (apple)Positive and negative results
13 papers in the same direction as this paper · 7 in the opposite direction
- negative
- no effect
- negative
17 papers more in this group
See all 21 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.