Abstract
Dipping asparagus crowns (Asparagus officinalis L.) in 1000 ppm (2-chloroethyl)phosphonic acid (ethephon) solutions before planting significantly increased the number and fresh weight of both shoots and roots in pot studies. Ethephon treatment did not affect time of emergence, height, diameter of the shoots and root length. Of the concentrations tested (0, 250, 500, 750 and 1000 ppm), the 1000 ppm was the most effective; 750 ppm was partially effective while 250 and 500 ppm were ineffective. Under field conditions, ethephon and/or the potassium salt of gibberellic acid (KGA3) at 1000 ppm, did not affect the time of emergence of shoots from crowns treated before planting. Ethephon was effective in increasing the number of shoots while KGA3 alone or in combination with ethephon was not. Both chemicals reduced stand. Increasing exposure from 15 to 60 minutes increased the effectiveness of ethephon at 1000 ppm on inducing shoot emergence.
Flower bud hardiness of ethephon-treated (100 mg·liter-1 in October), dormant pruned (in December) `Redhaven' peach (Prunus persica L. Batsch.) trees was studied from December through March using exotherm analysis. In early December, buds not treated with ethephon were 0.5C hardier than ethephon-treated buds. From mid-December through March, ethephon-treated buds were 0.5 to 2.1C hardier than nontreated buds. When a main effect of pruning was detected, buds from pruned trees were 0.8 to 2.8C less hardy than buds from nonpruned trees. On several dates, a significant interaction on flower bud hardiness between ethephon treatment and pruning was detected. For trees not treated with ethephon, buds from pruned trees were 1.8 to 2.2C less hardy than those from nonpruned trees. Pruning did not affect hardiness of buds from ethephon-treated trees. Ethephon delayed bloom to the 75% fully open stage by 9 days. Pruning accelerated bloom to the 75% fully open stage by 3 days compared to nonpruned trees. Flower bud dehardening under controlled conditions was also studied. As field chilling accumulated, flower buds dehardened more rapidly and to a greater extent when exposed to heat. Pruning accelerated and intensified dehardening. Ethephon reduced the pruning effect. The percentage of buds supercooling from any ethephon or pruning treatment did not change as chilling accumulated. In trees not treated with ethepbon, fewer buds supercooled as heat accumulated, and pruning intensified this effect. In pruned, ethephon-treated trees, fewer buds supercooled after exposure to heat. The number of buds supercooling in nonpruned trees did not change with heat accumulation. Flower bud rehardening after controlled dehardening was also evaluated. After dehardening in early February, there was no difference in the bud hardiness of pruned or nonpruned trees. Buds from ethepbon-treated trees were hardier than those from nontreated trees. With reacclimation, buds from pruned trees were not as hardy as those from nonpruned trees. The percentage of buds supercooling from ethephon-treated trees did not change with deacclimation or reacclimation treatments. After deacclimation in late February, buds from pruned trees were 2.2C less hardy than those from nonpruned trees. After reacclimation, buds from pruned, ethephon-treated trees rehardened 2.6C while buds from all other treatments remained at deacclimated hardiness levels or continued to deharden. Ethephon-treated pistils were shorter than nontreated pistils. Pistils from pruned trees were longer than those from nonpruned trees. Deacclimated pistils were longer than nondeacclimated pistils. Differences in hardiness among ethephon and pruning treatments were observed, but there was no relationship between pistil moisture and hardiness.
Abstract
In recent years, the market price of lychee (Litchi chinensis Sonn.) has dropped steeply in the “on” year, depressing the incomes of farmers. If the flowering could be controlled, the problem could be alleviated. Normally flower bud formation of ‘Heh Yeh’ lychee occurs in late November and panicles emerge in mid-January of the next year. Nakata (3) and others obtained a flowering response in lychee with various concentrations of sodium naphthaleneacetate (SNA). Nakata indicated that blossoming of lychee in Hawaii is favored by dry autumn months followed by substantial rainfall from December to February. Under these conditions, SNA appeared to inhibit vegetative growth, which was a prerequisite for floral initiation. Attempts to induce flower bud formation with SNA and other chemical treatments have not been successful in Taiwan. The objective of this study was to determine the effect of ethephon and kinetin on shoot growth and flower bud formation of field-grown lychee in Taiwan.
In the daffodil pot plant forcing industry, ethephon sprays have been the most common method of height control ( de Hertogh, 1996 ), but they are not always effective (W.B. Miller, personal communication; Moe, 1980 ). In a previous paper ( Miller
production costs in other fruit commodities. Ethephon is the a.i. (21.7%) in Ethrel® (Bayer Crop Science, Research Triangle Park, NC), a systemic PGR that, in solutions of pH 4 or higher, decomposes to ethylene, phosphate, and chloride ions ( Royal Society of
Ethephon [(2-chloroethyl) phosphonic acid] is a plant growth regulator (PGR) belonging to the phosphonate family ( Abeles et al., 1992 ). It is absorbed rapidly by aboveground plant parts, and releases ethylene readily at the pH of most plant
Replicated studies were conducted from 1996 to 1999 to evaluate the effect of a metalized reflective film (RF) on red color development in several apple (Malus ×domestica) cultivars that often develop poor to marginal color in the mid-Atlantic growing region. Film was applied to the orchard floor in the middle between tree rows or under the tree beginning 5 to 7 weeks before the predicted maturity date. Light reflected into the canopy from the RF was measured and compared with a standard orchard sod, a killed sod or various polyethylene films. Fruit color was estimated visually and with a hand-held spectrophotometer. Fruit quality (firmness, soluble solids, starch index) was determined from a representative sample of fruit. RF increased the level of photosynthetic photon flux (PPF) reflected into the canopy resulting in darker, redder colored `Delicious', `Empire', and `Fuji' apples with a greater proportion of surface showing red color. RF increased canopy temperature and fruit surface temperature. A white polyethylene film increased reflected PPF and fruit color, but generally not to the extent of the metalized RF. Large [>13 ft (4.0 m) height] well-pruned `Delicious' trees showed increased fruit color, especially when the RF was placed under the canopy, but `Empire' trees of similar size and a more dense canopy showed no effect. The effect of the RF was most pronounced in the lower portion [up to 8 ft (2.4 m) height] of the canopy. A high-density RF was as effective as a low-density RF and the high-density film was about 60% less expensive. A high-density RF may be a cost effective method to enhance red color on selected apple cultivars in the mid-Atlantic region. Comparisons between ethephon and the RF were variable: ethephon appeared to have more effect on color in `Empire' than the RF, but less effect than the RF on `Hardibrite Delicious'. Ethephon consistently advanced fruit maturity. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).
., 1988 ; Rademacher, 2000 ). In contrast, ethephon [(2-chloroethyl) phosphonic acid] is a PGR that releases ethylene (C 2 H 4 ), chlorine (Cl – ), and hydrogen phosphate (H 2 PO 4 − ) on application and is known to inhibit internode elongation, induce
, environmental factors, including temperature, relative humidity (RH), and plant stress, have a great influence on the ethephon response ( Klein et al., 1978 ; Martin et al., 1981 ). Ethephon causes leaf abscission, which can compromise the next year
Ethephon [(2-chloroethyl) phosphonic acid] has been widely used as a foliar spray in the commercial greenhouse industry for decades to abort flowers, promote branching, and restrict plant growth ( Kays and Beaudry, 1987 ). Growers have reported