Pre- and Post-harvest Physiology of Cymbidium Orchids

L. C. De; P. Deb; Geetamani Chhetri; Deepak Rai

Pre- and Post-harvest Physiology of Cymbidium Orchids

L. C. De

, P. Deb

, Geetamani Chhetri

, Deepak Rai

ICAR-NRC for Orchids, Pakyong, Sikkim, India

Author

Correspondence author
International Journal of Horticulture, 2015, Vol. 5, No. 6 doi: 10.5376/ijh.2015.05.0006
Received: 24 Mar., 2015 Accepted: 03 May, 2015 Published: 20 May, 2015

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Preferred citation for this article:

De et al., 2015, Pre- and Post-harvest Physiology of Cymbidium Orchids, International Journal of Horticulture, 2015, Vol.5, No.6 1-5 (doi: 10.5376/ijh.2015.05.0006)

Abstract

In the present study, an effort has been made on pre-harvest physiology of Cymbidium orchid hyb. ‘Pine Clash Moon Venus’ as effected by pre-harvest foliar treatments and post-harvest physiology as effected by bud opening chemicals. Pre-harvest foliar application with GA₃ (50 ppm) + BA (200 ppm) increased length of spikes, rachis length, number of florets per spike and flower longevity on plants in orchids. Longest spike (60 cm), rachis (30cm), highest number of spikes /plant (4) and number of florets per spike (15) were found with GA₃ (50 ppm) + BA (200 ppm). Carbohydrate content in leaf was estimated maximum with BA (200 ppm) (182mg/g) followed by GA₃ (50 ppm) + BA (200 ppm) (170mg/g). Highest per cent of fully opened buds (75%) and maximum vase life (45 days) were recorded with the chemical combination of Sugar 4% + Salicylic acid 200 ppm. Highest content of carbohydrate (140mg/g) was estimated at bud stage in fresh condition. Minimum carbohydrate content (60mg/g) was observed with Sugar 4% + 8-HQS (200 ppm) followed by Sugar 4% + Salicylic acid 200 ppm) (64mg/g).

Keywords

Cymbidium; Bud opening; Longevity; Carbohydrate

Cymbidiums are among the most popular winter and spring blooming semi-terrestrial orchids originated from tropical and subtropical Asia, usually growing in cooler climates at high elevations. Cymbidiums are famous for its beautiful long lasting spikes derived from species and hybrids. Post –harvest life of orchid cut flowers is influenced by pre-harvest factors like varietal differences, light intensity, sugar level of flowers, temperature and water loss; harvest factors including time and stage of harvest and post-harvest factors viz. ethylene production, pre-cooling, pulsing, use of preservatives, packaging and storage. In Cymbidium, 75% bloom stage with the spike length of 60-90 cm shows vase life of 55-60 days. Bud opening of flowers increases longevity of cut flowers by reducing the sensitivity of flowers to extreme temperatures, low humidity and ethylene, saving space during shipment and extending the useful storage life. The sugar concentration used is lower than the concentration of pulsing and the optimum temperature is kept lower.

1 Materials and Methods

In the present investigations, three experiments have been carried out at NRC for Orchids, Pakyong, Sikkim during 2010-11 and 2011-12 to study the effect of pre-harvest treatments on growth and flowering, vase life and post-harvest treatments for opening of tight buds of cut flowers of Cymbidium hyb. ‘Pine Clash Moon Venus’.

1.1 Pre-harvest treatment

In the first experiment, there were altogether 11 foliar treatments including control laid out in CRD design with 9 replications. Treatments were control, 0.3% NPK (19:19:19), Cow urine (1:20), Coconut water (1:10), Calcium nitrate (1%), Micronutrient mixture (0.05%), Glucose (0.1%), Mustard cake (1kg/50 litres), GA₃ (50 ppm), BA (200 ppm), GA₃ (50 ppm) + BA (200 ppm). All the foliar treatments were applied at 15 days interval from March to September till initiation of spikes. Observations were recorded on pseudobulb size (cm), maximum leaf length of flowering pseudobulb (cm), spike length (cm), rachis length (cm), number of spikes/plant, number of florets/spike, floret diameter (cm) and flower longevity on plants (days).

1.2 Estimation of total carbohydrates at flowering stage

Changes in total carbohydrate content of pseudobulb, leaf and flowers for all the 11 treatments were estimated at flowering stage using Phenol Sulphuric Acid Method (Bhattacharjee and De, 2005). Each 100mg of the tissues were hydrolyzed by keeping in boiling water bath for 3 hours with 5ml of 2.5N HCl and cooled to room temperature. Then it was neutralized with sodium carbonate until effervescence ceases and made up to the volume to 100 ml and centrifuged. 0.2, 0.4, 0.6, 0.8 and 1 ml of the working standard were pipetted out into a series of test tubes. The sample solution of 0.1 ml and 0.2ml was pipetted out in two separate test tubes and made up the volume in each tube to 1 ml with water. A blank with 1ml of water was set. 1ml of phenol solution was added to each tube. 5ml of 96% sulphuric acid was added to each tube and shaken well. After shaking for 10 minutes, tubes were placed in water bath at 25 to 30^oC for 20 minutes. The colour was read at 490nm. The amount of total carbohydrate present in the sample was calculated using the standard graph.

1.3 Analysis of post-harvest life

In the second experiments, five flowers for all the treatments were evaluated in tap water in CRD design. Major post-harvest parameters including reduction in weight (g), longevity of first floret (days), solution uptake (ml) and vase life (days) were recorded.

1.4 Bud opening treatments

In the last experiment, seven bud opening treatments viz. sugar (4%), sugar (4%) + Al₂(SO₄)₃ (100 ppm), sugar (4%) + 8-HQS (200 ppm), sugar (4%) + Salicylic acid (200 ppm), sugar (4%) + Ca (NO₃)₂ (1%), sugar (4%) + boric acid (200 ppm) + K₂SO₄(2mM) including control (distilled water) were laid out in CRD design with five replications. 45cm long flower spikes were harvested at bud stage and treated with all the above chemicals for opening. Observations recorded on days to first floret opening, diameter of first floret, percent of half opened buds, per cent of fully opened buds and vase life.

1.5 Estimation of total carbohydrates at senescence stage

Changes in total carbohydrate content of flowers at senescence were estimated using Phenol Sulphuric Acid Method (Bhattacharjee and De, 2005).

2 Results and Discussion

Growth of pseudobulb (6cm) was promoted with the applications of 0.3% NPK (19:19:19), Glucose (0.1%), Mustard cake (1kg/50 litres), BA (200 ppm) and GA₃ (50 ppm) + BA (200 ppm) (Table 1). Maximum leaf length (90cm) was recorded with the application of GA₃ (50 ppm) + BA (200 ppm).

Table 1 Growth, flowering and longevity of Cymbidium hyb. ‘PCMV’ as affected by pre-harvest treatments

2.1 Flower quality and longevity

Good quality cut flowers with longer spike and rachis length were observed with the pre-harvest foliar treatments of GA₃ (50 ppm) + BA (200 ppm), Glucose (0.1%), Micronutrient mixture (0.05%) and coconut water (1:10). Longest spike (60 cm), rachis (30cm) and highest number of spikes /plant (4) were found with GA₃ (50 ppm) + BA (200 ppm) (Table 1). Increase in rachis length due to GA₃ application has been studied in gladiolus (Palanikumar and Bhattacharjee, 2003, Srivastava et al., 2005). Number of florets per spike varied significantly with all the treatments. Maximum number of florets per spike (15) was recorded with GA₃ (50 ppm) + BA (200 ppm) followed by Glucose (0.1%) (14).

Foliar application with all the three growth regulators enhanced flower longevity more than 100 days and highest longevity of flower spikes was observed with (115 days) GA₃ (50 ppm) + BA (200 ppm) (Table 1).

2.2 Carbohydrate content at flowering stage

Changes in carbohydrate content of pseudobulb, leaf and flower had shown significant variable response for the treatments. Highest carbohydrate content of pseudobulb (242 mg/g) and flower (164mg/g) were recorded with cow urine (1:20). Carbohydrate content in leaf was estimated maximum with BA (200 ppm) (182mg/g) followed by GA₃ (50 ppm) + BA (200 ppm) (170mg/g) (Table 2). Total carbohydrate content was estimated maximum with cow urine (1:20) (552 mg/g) followed by 0.3% NPK (19:19:19) (484mg/g) and micronutrient mixture (460mg/g). Carbohydrates reserves of pseudobulbs and leaves have greatest impact on development of shoots and inflorescence in orchids (Hew and Ng, 1996, Ng and Hew, 2000).

Table 2 Changes in carbohydrate content (mg/g) at flowering stage in Cv. ‘Cymbidium’ as affected by pre-harvest treatments

2.3 Post- harvest life

There was significant variation on reduction in changes of fresh weight of cut flowers for all the treatments. Minimum reduction of fresh weight of cut flowers (4g) was observed with BA (200 ppm) followed by GA₃(50 ppm) + BA (200 ppm (5g) (Table 3). Calcium nitrate (1%) and Micronutrient mixture (0.05%) had shown maximum reduction of fresh weight of cut flowers (38g). Longevity of first floret and vase life of spikes significantly varied with all pre-harvest treatments. Longevity of first floret was found maximum (62 days) with BA (200 ppm) while maximum vase life (80days) was recorded with Coconut water (1:10) (Table 3). Cytokinins play a key role in initiation of cell division, delaying senescence and subsequently increases vase life (Anju Pal et al., 2003).

Table 3 Post-harvest life of Cym. ‘PCMV’ as affected by pre-harvest treatments

2.31 Bud opening of cut flowers

Opening of tight buds of cut flowers of Cymbidium orchids was improved with all chemical treatments except control. Minimum duration (18 days) for opening of first floret was observed with Sugar 4% + 8-HQS (200 ppm). The treatment combination of Sugar 4% + Salicylic acid 200 ppm had first floret with maximum diameter (6.6cm) (Table 4). Per cent of half opened buds was recorded maximum (30.7%) with Sugar 4% + 8-HQS (200 ppm) whereas per cent of fully opened buds was highest (75%) in Sugar 4% + Salicylic acid 200 ppm. In control, all flower buds dropped on 27^th days. Vase life of cut spikes was found maximum (45days) with Sugar 4% + Salicylic acid (200 ppm) followed by Sugar 4% + Al₂(SO₄)₃(100 ppm) and Sugar 4% + 8-HQS (200 ppm) (44 days). Bud opening, improved flower size and enhancement of vase life of tight bud cut flowers of Cymbidium orchids as treated with Sugar 4% + Salicylic acid (200 ppm) may be attributed to effect of salicylic acid as anti-transpirant by induction of stomatal closure or by blocking the conversion of a amino cyclopropane -1-carboxylic acid to ethylene (Leslie and Romani, 1986). Earlier opening of first floret was observed with Sugar 4% + 8-HQS (200 ppm) and it may be associated with improvement of water balance and antibacterial activity of 8-HQS (Ichimura et al., 1999). In addition, flower opening has been reported to be dependent on carbohydrate levels in the petals (Van Doorn et al., 1991b).

Table 4 Effect of chemicals on bud opening in Cymbidium hyb. ‘Pine Clash Moon Venus’

2.4 Carbohydrate content at senescence stage

Changes in carbohydrate content of cut flowers at senescence stage had shown significant variations starting from flower bud to flower opening stage. Highest content of carbohydrate (140mg/g) was estimated at bud stage in fresh condition followed by at bud stage (131mg/g) at senescence in control. Minimum carbohydrate content (60mg/g) was observed with Sugar 4% + 8-HQS (200 ppm) followed by Sugar 4% + Salicylic acid 200 ppm) (64mg/g) (Table 5). Exogenous sugar replaces the depleted endogenous carbohydrates utilized during the post-harvest life of flowers. At senescence, minimum carbohydrate content (60mg/g) was found with Sugar 4% + 8-HQS (200 ppm) followed by Sugar 4% + Salicylic acid 200 ppm) (64mg/g) indicated that more amount of carbohydrates have been utilized during flower opening and increasing vase life.

Table 5 Changes in total carbohydrates as affected by effect of chemicals on bud opening of Cym. ‘PCMV’ harvested at bud stage

References

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Bhattacharjee S.K., and De L.C., 2005, Post-harvest Technology of Flowers and Ornamental Plants, Aavishkar Publishers, Jaipur, Rajasthan, pp. 440

Hew C.S. and Ng C.K.Y., 1996, Changes in mineral and carbohydrate content in pseudobulbs of the C3 epiphytic orchid hybrid Oncidium Goldiana at different growth stages, Lindleyana, 11: 125-134

Ichimura K., Kojima K., and Goto R, 1999, Effect of temperature, 8-HQS and sucrose on the vase life of cut rose flowers, Post –Harvest Biology and Technology, 15: 33-40
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Van Doorn W.G., de Stigter H.C.M. de Witte Y. and Boekestein A., 1991b, Microorganisms at the cut surface and in the xylem vessels of rose stems: a scanning electron microscope study, Journal of Applied Bacteriology, 70: 34-39
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