Effects of Plant Growth Regulators and Flower Stalk Removal on Growth and Flowering of Oncidiums
Date Issued
2009
Date
2009
Author(s)
Chang, Wei-Chien
Abstract
Oncidium cut flower has problem of intensive production period. First, this study aimed to investigat the effect of cytokinins(CTKs) and gibberellins(GAs) on growth and flowering of Oncidium Gower Ramsey. Secondly, we investigated the effect of removing flower stalks in different seasons on vegetative growth and flowering date of Oncidium Gower Ramsey, in order to hasten or delay flowering period. Potted flower varieties of Oncidium bear attractive flowers with patterns and colors that have potential in the future. The second part of the study aimed to investigate the factors contributing to Colmanara Wildcat ‘Golden Fairy’ flower senescence and extend flower longevity by plant growth regulators. xperiment on effect of CTKs and GAs on growth and flowering of Oncidium showed, treatment with 0.2、0.4 or 0.8 mM BA increased the number of vegetative buds either applied before or after flower stalk emergence. Treatment with 0.8 mM BA before flower stalk emergence, postponed the time of flower stalk emergence, anthesis and harvest and reduced the floret diameter. Treatment with 0.8 mM BA after flower stalk emergence did not flower and treatments with 0.2 and 0.4 mM BA delayed harvest. Meanwhile, treatments with different kind of CTKs (0.2, 0.4, or 0.6 mM BA or Kinetin) and GAs (0.3, 0.9 or 2.7 mM GA3 or GA4+7), or their combination during summer under plastic tunnel greenhouses. The results showed that GAs treatments hastened the days to inflorescence emergence, but did not affect the days to anthesis and inflorescence harvest, and the percentage of flower stalk emergence was higher with lower GAs concentration (0.3 mM). However, the older leaves turned chlorosis after GAs treatments. Among CTKs treatments, only BA treatments promoted the percentage of vegetative bud emergence, vegetative bud growth and increased the number of vegetative buds per plant. BA treatments inhibited flowering percentage significantly. BA combinated with GAs treatments promoted inflorescence and vegetative bud emergence. Except kinetin, all other chemical treatments reduced the growth of pseudobulbs.n seasonal flower stalk removing, five- to thirteen-cm flower stalks were removed on March 1st, 15th, 30th, July 15th and August 15th. March-removing treatments had more vegetative buds than control treatments, but the percentage of current shoot with second inflorescence is low (0%-16.7%). Flowering date of daughter shoots in March-removing treatments was around October, and did not shift the flowering period away from September to November. Flower stalk removing on July 15th and August 15th did not increase the number of vegetative buds, but the percentage of current shoot with secondary inflorescence (8.3%-41.7%) is higher than March-removing treatments. Two treatments achieved the ambition: 1) Removing 5-cm flower stalk on August 15th, the time of second flower stalk harvest delayed 60 days than control plants, and the period of harvest was during mid December. 2) Removing 5- to 13-cm flower stalk, the time of flower stalk emergence was 91-98 days earlier than control plants, and the period of harvest was from mid-March to early-April. Size of pseudobulb without second flower stalk was wider and thicker than plants with second flower stalk. n extending Colm. Wildcat ‘Golden Fairy’ flower longevity, ethylene production of floret was extreme low during senescence (<0.003 nL•g-1•h-1). Treatment with 0.8 μL•L-1 1-MCP for 6 hr and 1.5 mM STS (ethylene action inhibitor) did not extend flower longevity. Treatments with 25, 50, or 100 μM fluridone (abscisic acid synthetic inhibitor) delayed flower senescence, thus showed that abscisic acid other than ethylene may be more important factors on Colm. Wildcat ‘Golden Fairy’ flower longevity. However, the yellow coloration of florets reduced when fluridone was applied at green floral bud stage. Flower longevity was improved when higher concentration of BA (0.4 mM) applied at blooming stage was prolonged with 0.2 mM BA at bud stage. Treatment with 0.4 mM BA prolonged individual floret longevity among applied at the stages of full-opened floret, half-opened floret and half-colored floral bud.
Subjects
Plant Growth Regulators
Oncidiums
Flowering
Type
thesis
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