S-abscisic Acid Research Articles

THE EFFECTS OF NH4-N AND PLANT GROWTH REGULATORS ON PHALAENOPSIS SPIKING AND FLOWERING

In Phalaenopsis production, year around flowering is possible by temperature control. However, the cost of heating and cooling is high and the development of energy saving methods is a major concern. In this experiment, effects of nitrogen fertilizer and plant growth regulators (PGRs) on spiking were investigated. Nutrient solutions containing 26.2 mg/L NH 4 -N and 82.7 mg/L NO 3 -N (control), control + 140 mg/L NH 4 -N, or control + 140 mg/L Urea-N was applied weekly. Application of excess NH 4 -N delayed flowering by approximately two weeks. Urea-N showed no clear effects on delaying spiking. Naphthalene acetic acid sodium salt (NAA˙Na), Benzyladenine (BA), Thidiazuron (TDZ), gibberellin A 3 (GA 3 ) or s-abscisic acid (s-ABA) was applied to investigate the effects on spiking. Among the PGRs tested, weekly (6 to 16 times) or biweekly (6 to 10 times) applications of 1,000 mg/L NAA˙Na delayed spiking of Phalaenopsis. S-ABA also delayed spiking, more by 6 weekly applications. GA 3 and BA showed no clear effects. TDZ stimulated vegetative or reproductive lateral bud growth markedly, depending on the air temperature. Combined application of NH 4 -N and NAA˙Na 23 times showed clear additional inhibitory effect on spiking. Combined application of NH 4 -N and s-ABA affected inflorescence growth differently, depending on the s-ABA concentrations. To elucidate an efficient and practical NAA˙Na application method, application with a Finnpipette, sprayer, alginic acid or Gelrite gel pellets containing NAA˙Na were experimented. Application with a Finnpipette was the most effective, followed by a sprayer. Application by alginic acid gel showed slight effects, but Gelrite gel showed no effects.

Abscisic Acid Applications Decrease Stomatal Conductance and Delay Wilting in Drought-stressed Chrysanthemums

Drought stress during shipping and retailing reduces the postproduction quality and marketability of potted plants. Plants respond to drought stress by closing their stomata and reducing transpirational water loss. This stress response is mediated by the plant hormone abscisic acid (ABA). Exogenous applications of s-abscisic acid (s-ABA), the biologically active form of the hormone, can enhance drought tolerance and extend shelf life in a variety of bedding plants. However, little is known about the effectiveness of s-ABA at enhancing drought tolerance in perennial crops like chrysanthemum (Chrysanthemum ×morifolium). ‘Festive Ursula’ chrysanthemum plants were drenched (0, 125, 250, or 500 mg·L−1) or sprayed (0, 500, or 1000 mg·L−1) with s-ABA. All applications containing s-ABA effectively delayed wilting by reducing stomatal conductance (gS). Shelf life was extended from 1.2 to 4.0 days depending on the concentration of s-ABA. Spray applications of 500 mg·L−1 s-ABA to six additional chrysanthemum cultivars increased shelf life from 1.6 to 3.8 days following drought stress. s-ABA treatment also allowed severely drought-stressed chrysanthemums to recover and remain marketable after rewatering. Growers can treat chrysanthemums with s-ABA to reduce water use during shipping and to delay wilting if plants are not adequately watered during retailing.

Effect of S-Abscisic Acid Application on Soybean Grain Yield under Different Condition of Water Stress

Effect of S-Abscisic Acid Application on Soybean Grain Yield under Different Condition of Water Stress

2,4-Dichlorophenoxyacetic Acid Increases Peonidin Derivatives in Red Norland Periderm

Studies were conducted to determine the effects of selected plant growth regulators on red color development of Red Norland potato periderm, and the mechanism by which color changes occurred. Two derivatives of the auxin 2,4-dichlorophenoxyacetic acid (2,4-D ester and 2,4-D amine), S-abscisic acid, n-propyl dihydrojasmonate, and the ethylene synthesis inhibitor aminoethoxyvinylglycine were foliar applied at 4, 6, and 8 weeks after emergence. Only the 2,4-D ester and 2,4-D amine significantly improved tuber periderm red color in two seasons of evaluation. Red color faded during storage regardless of treatment. Anthocyanin content at vine kill was significantly increased by 2,4-D treatment in 2004 but not 2005. The 2,4-D treatments increased the ratio of peonidin derivatives to pelargonidin derivatives compared with controls. This change in ratio may explain the observed change in hue angle with 2,4-D treatment compared to controls.

Abscisic Acid Application Timing and Concentration Affect Firmness, Pigmentation, and Color of `Flame Seedless' Grapes

Poor coloration of red grapes grown in warm regions is a frequent problem that decreases production efficiency. Most table grape growers use ethephon to improve color, but its influence on color development is erratic, and it may reduce berry firmness. Application of S-abscisic acid (ABA) to grapes can increase the anthocyanins in their skins, but no protocols have been established regarding its potential commercial use. Therefore, we evaluated the effects of ABA and ethephon treatments on fruit quality characteristics, including those related to firmness and color, on `Flame Seedless' grapes (Vitis vinifera L.) in several experiments over three consecutive seasons. Abscisic acid had few effects on berry weight or juice composition, but it increased berry softening and skin anthocyanin concentrations. The effect of ABA on berry firmness was similar to ethephon. With respect to skin anthocyanin concentration and fruit color characteristics, 300 mg·L–1 ABA applied at veraison was superior to the other ABA concentrations and to ethephon applied at any of the times tested. Moreover, any concentration of ABA between 75 and 300 mg·L–1 applied after veraison improved color better than ethephon applied at the same time. There was a highly significant inverse curvilinear relationship between skin anthocyanin concentration and the lightness and hue of the berries. Anthocyanin concentrations between 0.01 and 0.04 mg·cm–2 had little effect on berry lightness and hue, so researchers should consider measuring color, not just anthocyanins, when evaluating the quality of red table grapes.

Water Status of Tomato Plugs Sprayed with (+)-S-Abscisic Acid and Stored in the Dark at Room Temperature.

The effects of (+) -S-abscisic acid (ABA) on the water status of stored tomato (Lycopersicon esculentum Mill.) plugs were investigated. Plugs were sprayed at the 4-leaf stage with ABA at 0, 20, 100, or 500 mg L-1 and stored in the dark at room temperature for 10 d. The water status of the plugs and soil was measured with isopiestic psychrometers. No growth occurred during storage. Untreated plugs wilted : the water potential and turgor of their leaves decreased significantly. However, the water potential and turgor of leaves treated with ABA were maintained. These results suggest that ABA treatment reduces wilting by controlling transpiration and osmotic adjustment.

Induction of ABA 8′-hydroxylase by (+)- S-, (−)- R- and 8′,8′,8′-trifluoro- S-abscisic acid in suspension cultures of potato and Arabidopsis

Suspension cultures of potato and Arabidopsis were incubated with 50 μM of (+)-ABA and (−)-ABA for 3 hr. These pretreatments were found to increase the rate, by two- to seven-fold, of formation of [ 2H 6] phaseic acid (PA) from [ 2H 6] ABA, applied in a subsequent incubation. Pretreatment with trifluoro-ABA had a higher efficacy, increasing the rate of conversion 15-fold. Suspension culture cells that had been dehydrated and then rehydrated in the presence of [ 2H 6] ABA displayed a much lower enhancement of PA formation. We conclude that ABA induces its own oxidative catabolism in suspension cultures. ¢ 1997 Elsevier Science Ltd. All rights reserved

Abscisic acid both promotes and inhibits photoperiodic flowering of Pharbitis nil

Abscisic acid (ABA) has been reported to have diverse effects on photoperiodic flowering. Activity of a natural ABA, (+)‐(S)‐abscisic acid (S‐ABA), was recently suggested to be somewhat different from that of racemic ABA, which has been used in previous work. Use of S‐ABA might enable clarification of the role of ABA in flowering. S‐ABA inhibited flowering of the short‐day plant Pharbitis nil (cv. Violet) when given before or 4 h after the start of a 14‐h inductive dark period, and promoted flowering when given 12 h after the start of the dark period or later. The flower‐promoting effect was observed when ABA was applied to the shoot apex. These results indicate that ABA has a dual effect on photoperiodic flowering of P. nil: it may inhibit the time‐measuring process as well as promote some processes that proceed after generation of the flowering stimulus.

Effects of (+)-S-Abscisic Acid on the Quality of Stored Cucumber and Tomato Seedlings

Effects of ABA on the quality of stored cucumber (Cucumis sativus L.) and tomato (Lycopersicon esculentum Mill.) seedlings were investigated in two experiments. Foliarly applied ABA (20, 100, or 500 mg·liter–1) decreased transpiration of stored, pot-grown, cucumber seedlings at 8, 15, and 20C. Seedlings stored at 15 and 20C were slender with long internodes. At these temperatures, ABA at 100 and 500 mg·liter-1 reduced plant internode length. Seedlings stored at 8C and those not stored were short, and ABA did not affect internode length. A decrease of chlorophyll content in the first leaf of seedlings stored at 20C was less pronounced with ABA. In the second experiment, the effect of a foliar ABA application on stored, plug-grown, cucumber and tomato seedlings was determined. When seedlings were stored at 20C, those sprayed with ABA did not wilt, but nontreated seedlings did wilt. No seedlings wilted when stored at 8 and 15C. These results suggest that ABA could be used to maintain the quality of cucumber and tomato seedlings stored at 15 or 20C. Chemical name used: (+)-S-abscisic acid (ABA).

The Resolution by HPLC ofRS-[2-14C]Me 1', 4'-cis-Diol of Abscisic acid and the Metabolism of (−)-R- and (+)-S-Abscisic Acid

The R- and S-enantiomers of racemic [2-14C]Me l',4'-ris-diol of abscisic acid have been separated by high performance liquid chromatography on an optically-active Pirkle column. i?-[2-14C]- and S-[2-I4C]abscisic acids, formed from the Me l',4'-cw-diol by oxidation and alkyline hydrolysis were fed to tomato shoots and the extracts analysed by reversed phase high performance liquid chromatography. /?-[2-14C]abscisic acid formed mainly the abscisic acid glucose ester (ABAGE), abscisic acid l'-glucoside (ABAGS) and an uncharacterized conjugate. Dihydrophaseic acid 4'-/?-D-glucoside, the major metabolite of i?S-abscisic acid in tomato shoots, was found to be derived virtually exclusively from the natural, S-abscisic acid. Phaseic acid and conjugates of abscisic acid were also found as products of the naturally occurring enantiomer. The resolution method was used to measure the relative proportions of R and S enantiomers in the free acid liberated from conjugates formed from i?5-[2-14C]ABA fed to shoots. The ratios show an excess of the R-enantiomer: 5-8:1, ABAGE; 29-4:1, ABAGS; 8-3:1 for an uncharacterized conjugate and 6-1:1 for the residual free [2-14C]ABA.