For the quality improvement using growth regulator in pot plants and cut flowers, recent works were reviewed as in the following summary.
1. Criteria of flower quality evaluation.
Flower quality evaluation mainly depends on consumers multivariates sensory evaluation. Superior qua lily- commodity- can be defind as a cultivar having own gene characters without any faults during :he cultivation period. While it is expected to improve qualities of potted flowers or cut flowers, using hormones or chemicals supplied to the plant body.
2. Growth regulators for the quality improvement of pot plants.
For keeping balance and making share for pot plants several chemicals have shown some recommendable effects. Methyl esters of fatty acid having C_9 to C_(12) as chemical pinch agent were used. For axillary bud sprouting hormones (cytokinins, gibberellins), growth inhibitors (TIBA, morphactin, dikegulec sodium and erhephon) and growth retardants (daminozide and ancymidol, etc.) have also been used. About 17 kinds of chemicals have been sued, and new chemicals are producing continuocsly every year. Among them, cholormequat, daminozide and ancymidol as growth retardant were shown to be highly efficient, but the efficiency seemed to be dependent on kinds and cultivars of plants. Particulaly ancymidol broadened the use for a wide spectrum of pot plants. The tall monecotyledenous bulb plants are produced in pots by treating them with it. Mechanism of these growth retradants is that it changes endogenous hormone ratio and especially inhibits the gibberellin synthesis, which in turn reduces tree size, resulting in increased adaptability to various stress. In addition to physicochemical charachemical characters, their application measures were also reviewed.
3. Improvement out flower quality.
The senecense of out flowers was caused by stem plugging, decrease of sugar level, ethylene generation and lack of physiological water in the plants. Among the preharvest environmental conditions, sun light, balenced fertilization, CO₂application and suitable temperature were highly effective to the postharvest qualities. Deionized, millipore filtered or acidificated water prolonged out flower longevity. Ethylene being a ringleader of senescence is accelerated to emiz in the process of pollinetion, other ethylene gas emission and abscisic acid (ABA) level increment in the plant. Environment or other conditions such as autumn and winter, closed space, imperfect combustion, fruit ripening, mechanical injury, pest and disease infection accelerate ethylene emission promote senescence.
Reports for the long term keeping quality of out flower shows that a series of treatment such as early harvesting, pulsing and bud opening solution treatment contributed cut flower logevity increment.
Sucrose is a main component for pulsing, bud opening and holding solution, and the concentration and treatment time were absolutely depended on kinds of plants and cultivars. In mineral solutes, AgNO₃ or silver thiosulphate (STS), Al₂(SO₄)₂, boric acid, NiCl₂ and Cu-salts resulted in positive effects in extending longevity.
Germicides such as 8-hydroxy-quinoline sulphate (HQS) or citrate (HQC), slow release chlorine compounds (sodium dichloro-5-triazinetrione, 1.3-dichloro-5.5-dimethyl hydantoin), quaternary ammonium compounds having C_8 to C_(18) (n-alkyle dimethyl benzyl ammonium chloride, dimethyl benzyl ammonium chloride, Jury dimethyl benzyl ammonium chloride, n-alkyl trimethyl benzyl ammonium bromide), thiabandazole (TBZ), dichlorophen, chlorhexidine (digluconte and diacetate) gave a good longevity also. Orgarnic acid and salts including citric acid, tatarie acid, benzoic acid, iso-ascorbic acid and Na-ascorbate together with hydrazine sulphate as antioxidants were reported to be effective on the longevity.
Ethylene inhibitors were reported to be Ag, Ni, Co, HQ, TBZ, benzoic acid, aminoethoxyvinyl glycine (AVG) and methoxyvinyl glycine (MVG) as rhizobitoxine analogue, aminoxyacetic acid (AOA), benzothiadiazole, 5-methyl-7-chloro-4-ethoxy-carbonyl-methoxy-2, 1, 3-benzothiadiazole (TH-6241), benzyl iso-thiocyanate and ethanol.
Among phytohormones, cytokinine extented the longevity greately but anain, gibberellin and low .concentration of ABA did it partially. In addition to growth retardants like daminozide and CCC, growth inhibitor such as malefic hydrazide were reported to be effective for the extension of longevity, but the latter caused occassional harmful injury.
Sodium azide, 2.4 dinitrophenol as an enzyme inhibitor extended cut flower longevity also.
The proper regimes of storage temperature of cut flowers were disclosed to be dependent to the place of flower origins: tropical; 12∼18℃, sub-tropical; 2∼8℃, temperate zone; near 0℃ but there were reports showing different storage temperature regimes respective zones. Controlled or modified atmosphere storage and low pressure storage (hypobaric storage) can be kept longer term than the normal storage.
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