Sex expression in cucumber plants as affected by 2-chloroethylphosphonic Acid, ethylene, and growth regulators

The effects of 2-chloroethylphosphonic acid (Ethrel), ethylene, and some growth retardants on sex expression of cucumber plants (Cucumis sativus L.) were investigated, with the use of a monoecious cultivar (Improved Long Green) which has a strong tendency toward maleness.     

Effects of ethylene and acetylene on mango fruit ripening

Mangoes (var. Tommy Atkins) were exposed to ethylene and acetylene over a range of concentrations at high humidity for 24 h at 25°C, then ripened in air alone. Ripeness was assessed after 4 and 8 days by analysis of texture, colour development, soluble solids and acid contents. Ethylene in air at concentrations of 0.01 ml litre^-1 and above or acetylene at 1.0 ml litre^-1 were found to initiate ripening. Treatment with 0.01 ml litre^-1 acetylene resulted in limited softening but had no effect on the other ripening changes analysed. Individual ripening processes responded differently to treatment: texture changes were most rapidly affected, while the rate of acidity losses was often reduced in ethylene treated fruits. Acetylene-treated fruits at concentrations of 0.01 and 0.1 ml litre^-1 showed delayed ripening when compared to those treated with either 1.0 ml litre^-1 acetylene or ethylene. Increased acetylene concentrations of 2.0 ml litre^-1 gave a similar response to 1.0 ml litre^-1, although in some instances there were indications of inhibitory effects.     

Effect of water vapor pressure on the thermal decomposition of 2-chloroethylphosphonic Acid

Decomposition of 2-chloroethylphosphonic acid (Ethephon) was studied in dried films at various water vapor pressures (0.6 to 86.9 millimeters Hg, 3.2 to 93.9% relative humidity) and temperatures (20, 30, 40, and 50 C) at pH 6.3 and 7.0. The rate of decomposition could be determined equally well by [¹⁴C]Ethephon or ethylene measurements. The rate increases at increasing water vapor pressures at a constant temperature and pH, up to an optimum. The optimum vapor pressure for decomposition approximately doubles for each 10 C increase. The activation energy for the decomposition reaction in water vapor pressures of 3.2 to 12 millimeters Hg is 8.7 and 14.3 kilocalories per mole at pH 6.3 and 7.0, respectively.     

Potentiation and inhibition of the effects of 2-chloroethylphosphonic Acid by malformin

Malformin completely inhibited Ethrel-induced swelling and fresh weight increase on the basal stem portion of Phaseolus vulgaris L. cuttings, but markedly potentiated Ethrel- or ethylene-induced abscission. With regard to abscission, malformin reacted synergistically with ethylene and dark aging, and in a manner which appeared to differ from that of ethylene and dark aging. The numerous effects of malformin on plant growth and development cannot be explained in simple terms of enhanced ethylene production.     

Kinetic studies of the thermal decomposition of 2-chloroethylphosphonic Acid in aqueous solution

The decomposition of 2-chloroethylphosphonic acid in aqueous solution has been studied at pH values from 6 to 9 and at temperatures in the 30 to 55 C range. The rate of decomposition is estimated from the rate of formation of ethylene. The rate is proportional to the concentration of the phosphonate dianion and is independent of the hydroxyl ion concentration. The rate constant at 40 C is 1.9 × 10⁻⁴ sec⁻¹ and the activation energy is 29.8 kcal mol⁻¹. The rate of reaction is not affected significantly by the presence of potassium iodide or urea (substances which increase the rate of leaf abscission in trees sprayed by 2-chloroethylphosphonic acid). The rate decreases slightly in the presence of low concentrations of magnesium and calcium ions.     

Effects of treatment with a composite preparation (2-chloroethylphosphonic acid and methacide) or butylated hydroxyanisole on ethylene release in apples

We studied the effect of a Russian composite preparation (2-chloroethylphosphonic acid and methacide) and butylated hydroxyanisole on ethylene release in whole fruit and peel disks of two apple cultivars, Antonovka obyknovennaya (Antonovka) and Simirenko's rennet (Simirenko). Treatment with the composite preparation was followed by an increase in ethylene release from whole apples and peel disks. The development of microbial infection (fruit rot) in whole apples became less pronounced after the treatment. Treatment of whole apples with the antioxidant butylated hydroxyanisole (BHA) increased the intensity of ethylene release during the first subsequent days; thereafter, ethylene release decreased and was 10-15% lower than in the control on days 10-12. In model experiments, BHA decreased ethylene release from apple peel disks below control levels as early as on day 1 after the treatment. Antonovka apples gave quick responses to the treatment. In the late-ripening Simirenko apples, the response persisted for a longer period. Our results suggest that treatment with physiologically active preparations affects ethylene release, ripening, and preservation of apples in storage.     

Control of apple ripening by succinic Acid 2,2-dimethyl hydrazide, 2-chloroethyltrimethylammonium chloride, and ethylene

Ripening of `Tydeman's Early' apples (Malus sylvestris L.) assessed by the occurrence of the respiratory climacteric was delayed by succinic acid 2,2-dimethyl hydrazide (B-9) but not by 2-chloroethyltrimethylammonium chloride (CCC), each applied 14 days after bloom. B-9 also inhibited ethylene production by fruits exhibiting the climacteric rise. Inhibition of the climacteric by B-9 was overcome by exogenous ethylene, but the latter treatment failed to completely reverse the B-9 inhibition of endogenous ethylene production.     

Effects of aminoethoxyvinylglycine and countereffects of ethylene on ripening of bartlett pear fruits

Pear fruits (Pyrus communis L. var. Bartlett) were treated with solutions containing aminoethoxyvinylglycine (AVG) using a modified vacuum infiltration method that introduced 4.3 milliliters solution per 100 grams tissue. At concentrations of 1 millimolar, AVG strongly inhibited ethylene production and delayed for 5 days the respiratory climacteric and accompanying ripening changes in skin color and flesh firmness. AVG was less effective in inhibiting the ripening of more mature fruits. Fruit infiltrated with 5 millimolar AVG had not begun to ripen 12 days after initiation of ripening in the controls. When treated with ethylene the inhibited fruit exhibited a climacteric rise in respiration, softened, and became yellow. Treatment of the AVG infiltrated fruits with ethyelne for 24 hours resulted in no recovery in endogenous ethylene production, but in a stimulation of protein synthesis measured as a 200% increase in leucine incorporation by excised tissue and a 74% increase in the percentage of ribosomes present as polysomes.     

Accumulation of tartaric acid in the ripening process of grapes

1. 1. Tartaric acid content in grapes gradually increased withripening and reached a plateau about 50 days after flowering.
2. 2. Tartaric acid synthesis from ^14C0₂ was predominant in anearly ripening stage. When the berries were exposed to ^14CO₂8 days after flowering and examined two days later, 30% of thetotal ¹⁴C fixed was found in tartaric acid. Subsequently, apart of the tartaric acid decomposed, but the greater part remainedin the berries in a salt form. At the last stage of the ripeningprocess (82-100 days after flowering), some of the tartaratewas again converted to free acid. No ^14CO₂ was incorporatedinto tartaric acid when berries were exposed 61 days after flowering.
3. 3. L(+)-Tartaric acid-l,4-¹⁴C fed to the berries was catabolizedto ¹⁴CO₂. The ratio of radio activity recovered as ^{14 CO₂} tothat fed was nearly constant throughout the ripening process.
4. The cause of tartaric acid accumulation in grape berries isnot thought to be due to a lack of catabolizable enzymes, butto formation of an insoluble salt which is scarcely effectedby such enzymes.

(Received May 2, 1968; )     

Diurnal change of tartrate dissimilation during the ripening of grapes

l(+)-tartrate-[U-¹⁴C] or sucrose-[U-¹⁴C] was fed into grape berries and ¹⁴CO₂ evolution was determined. ¹⁴CO₂ evolution front l(+)-tartrate-[U-¹⁴C] was slightly higher in mature than immature berries, and that from sucrose-[U-¹⁴C] was higher in immature than mature ones. ¹⁴CO₂ evolution from l(+)-tartrate-[U-¹⁴C] was irregular throughout the day until 2 or 3 weeks after flowering. This stage shifted to regular ¹⁴CO₂ evolution until 6 or 7 weeks after flowering, and the mode of ¹⁴CO₂ evolution showed diurnal variation; higher in the day than at night. Then the stage without variation of ¹⁴CO₂ evolution followed 10 weeks after flowering. These observations indicate that tartrate is not biochemically inert in grape berries, while the amount of ¹⁴CO₂ evolution from sucrose-[U-¹⁴C] was higher at night than in the day through the whole ripening process, except in the early stage.     

The role of abscisic acid in the ripening of grapes

Ripening in grapes ( Vitis vinifera L. cv. Thompson seedless) was accompanied by an increase in the levels of sucrose, glucose and fructose and a decrease in the levels of acids. The activity of glucose-6-phosphatase and fructose-l–6-bisphospbatase was lower in sweet grapes as compared to sour ones. Abscisic acid (10⁻⁶ M) stimulated the gluconeogenic process in sour grapes. The levels of some gluconeogenic enzymes were also elevated in its presence. Cyclohexitnide (0.036–1.8 mM) nullified the abscisic acid effect, suggesting that this effect involves de novo protein synthesis. The incorporation of [¹⁴C]-leucine into proteins was enhanced about 80% by abscisic acid, confirming that abscisic acid promoted protein synthesis. Again, cycloheximide blocked the hormone mediated increase in the incorporation of radioactivity into proteins. The results indicate that one of the factors for sourness in certain mature ripe grapes may be that abscisic acid is not available.     

Effects of 1-MCP and exogenous ethylene on fruit ripening and antioxidants in stored mango

Mango (Mangifera indica L. cv. Tainong) fruits were harvested at the green-mature stage in Hainan and air-freighted to the laboratory at Peking. The fruits were treated with either 1 μl l⁻¹ 1-MCP or 5 μl l⁻¹ ethylene for 24 h and stored at 20°C for up to 16 days. 1-MCP maintained fruit firmness, whereas exogenous ethylene decreased fruit firmness. Exogenous ethylene accelerated the increase in ethylene and 1-aminocyclopropane-1-carboxylate (ACC) oxidase, whereas 1-MCP reduced both. Exogenous ethylene stimulated and 1-MCP inhibited the production of H₂O₂ of mango fruit during storage. Ascorbic acid was maintained at a high concentration in 1-MCP-treated fruit but was low in ethylene-treated fruit. 1-MCP inhibited activities of antioxidant enzymes including catalase, superoxide dismutase and ascorbate peroxidase. These results suggest that 1-MCP could play a positive role in regulating the activated oxygen metabolism balance. Baogang Wang and Jianhui Wang contributed equally to this work.     

Inhibition of apple ripening by succinic Acid, 2,2-dimethyl hydrazide and its reversal by ethylene

Ripening of McIntosh apples (Malus sylvestris L.) was delayed by treatments of succinic acid 2,2-dimethyl hydrazide (B-9) applied 2 weeks after bloom. The extent of retardation was dependent on concentration to 7.4 × 10⁻² m, at which level complete inhibition of ripening occurred under the conditions applied. The onset of the respiratory climacteric and fruit firmness changes were factors used to assess ripening.     

Dual effect of 2, 4-D on ethylene production and ripening of tomato fruit tissue

Tomato fruits (Lycopersicon esculentum Mill. cv. Indian River) were treated with aqueous solutions of 2, 4-dichlorophenoxyacetic acid (2, 4-D) and the effects on respiration, ethylene production, and ripening were examined. 10-³ and 10-⁵ M 2, 4-D solutions were used. Dipping treatment of whole fruit picked at the 74% stage of development, gave an increase in respiration and ethylene production, the effect being directly related to 2, 4-D concentration. Ripening was advanced relative to control fruit.
Tomato disks cut from the pericarp tissue of fruit picked at the 81% stage of development were vacuum-infiltrated with the same 2, 4-D solutions. In these disks the increase in respiration continued longer compared to control disks. Ethylene production was considerably increased, and after an initial recovery the 2, 4-D-treated disks showed another increase at a much faster rate than controls. However, contrary to what could be expected from this increase in ethylene, ripening was delayed. Nevertheless, all disk samples showed advance ripening compared to whole fruit of the same age, indicating that they could not recover completely from the effect of cutting and treatment.
The results showed that 2, 4-D causes a dual effect in tomato fruit tissue: an increase in ethylene production which promotes ripening, and a delay in ripening. This last effect, depending on the uniformity of the auxin distribution and its concentration, prevails.     

Effect of 2-chloroethylphosphonic acid on enzyme induction in barley endosperm

The effect of 2-chloroethylphosphonic acid (CEPA) on GA induction of α-amylase in the barley endosperm test was studied. No amylolytic activity could be detected when CEPA was substituted for GA. When CEPA was added simultaneously with GA it inhibited GA induction of α-amylase. Inhibition increased as increasing concentrations of CEPA were added. This inhibition is partially due to a direct influence of CEPA on the enzyme-starch reaction.     

Factors affecting the decomposition of 2-chloroethylphosphonic acid in soils

Abstract The ethylene-releasing compound 2-chloroethylphosphonic acid (ethephon) stimulates germination of dormant seeds under laboratory conditions and it may prove to be an effective means of administering ethylene to promote germination of seeds in the field. We examined the decomposition of ethephon in different soils to determine which properties of soils influence the activity (ethylene release) of ethephon. The release of ethylene from ethephon was not affected by the type of soil, the texture, the presence of organic matter, or levels of extractable SO^2?₄, PO^3?₄ NO^?₃, K⁺ or Na⁺. The rate of decomposition was, however, dependent on soil pH and was influenced by the soil moisture content. Very little ethylene was released from ethephon in soils with a pH <7.7 and with a moisture content < 10%.     

The significance of ethylene in the ripening of stored apples

Plants demonstrate various responses when subjected to relatively low concentrations of ethylene gas in the ambient air. The duration of exposure required depends on concentration and varies in different plants and according to stage and manner of growth. Several external factors may also influence the response of intact plants. Besides emissions from industrial installations, ethylene is produced externally from many natural sources and in consequence of human activities. The bulk of evidence suggests that ethylene is not at present a serious pollutant but we suggest that further and more precise research is required.