INTRODUCTION

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Flowers by nature attract every human being. Through all states in India have a tradition flowers, the commercial growing of flowers are presently confined to Karnataka, Tamilnadu, Andhar Pradesh, West Bengal, Maharashtra, Rajasthan, Uttar Pradesh, Delhi, Harayana. The major flowers grown in India are marigold, aster, roses, tuberous, gladiolus, jasmine, crossendra in open field while gerbera, carnation, roses, anthurium, orchids etc. are grown green house condition. The export of cut flowers from India is of Rs 253 million. India ranks 23^rd among world exporters of floriculture products and its share in the world exports are negligible at around 0.38% (US$ 47 million) (2004).  It is estimated that fresh cut flowers worth Rs. 100 crores are being exported annually from India. On the other hand the losses are estimated to be more than 30-35%. Several factors at pre harvest stage including genetic or inherent, climatic or environmental and management harvest factors like stage, method and time of harvesting, and post-harvest factors such as watering, rehydration, precooling, storage environment, packaging techniques and micro-organisms influence the post harvest quality and longevity cut flowers.

PRE-HARVEST FACTORS AFFECTING VASE LIFE

1. Genetic or inherent makeup: Postharvest lasting quality of flower species and cultivars vary considerably due to differences in their genetic make-up. Gladiolus varieties White Prosperity, Sancerre, Suchitra, Eurovision, Nova Lux, Rose Supreme and Trader Horn possess the better vase-life.
2. Growing conditions: Most cut flower crops require well-lighted conditions. On the contrary, too high light intensities cause scorching and dropping of leaves and abscission of petals. Flower crops are also specific in their temperature requirements Flowers also require adequate nutrients for good longevity. High nitrogen doses should be avoided as they increase susceptibility to diseases. For example, iron deficiency is commonly observed in gladiolus in north India, causing heavy yield losses. Flowering crop should also be grown away from the industries which release toxic effluent, gases, damaging the foliage as well as flowers. Flowers damaged by pathogens, insects and pests also show high ethylene production resulting in poor vase-life.
3. Stage, method and time of harvesting: Right stage, method and time of harvesting of flowers are of considerable importance to ensure their long vase-life. The stems should be cut with sharp knives or secateurs. Hardwood stems should always be given slanting cut to expose maximum surface are to ensure rapid water absorption. The flowers of dahlia and poinsettia release latex upon cutting. To overcome such problem, stems should be given a dip in hot water (80-90⁰C) for a few seconds.

The flowers of rose, carnation, gladiolus, tuberose, daffodils, lily, iris, freesia and tulip should be harvested at bud stage since their buds continue to open in water.. The flowers of snapdragon, Harvesting of flowers at bud stage is always preferred as their buds have long vase-life, are less sensitive to ethylene, easy to handle during storage and transport and are less prone to diseases and pests.

POST HARVEST FACTORS AFFECTING VASE LIFE

 Water relations: The termination of life of the harvested flowers depends on water uptake and transport, water loss and the capacity of the flower tissue to retain its water. A water deficit and wilting develop, when the transpiration exceeds absorption of water. The rate of water uptake of cut flowers depends on transpiration pull, temperature and composition of solutes . Disruption of water columns in stem vessels by air embolism and resistance to water flow in stems, also develop water deficit. Acidification of water and addition of wetting agent and flower food in the holding solution markedly improve water uptake of cut flowers.

1. Respiration: The rate of respiration depends on quantity of carbohydrates available in the harvested flowers, temperature and the use of certain chemicals to regulate it. With higher temperature, there is faster rate of respiration and burning of the tissue. Consequently, the life of flowers is shortened.
2. Relative humidity: It has, bearing on the transpiration rate. Higher the humidity in the air, less is the transpiration rate and vice-versa.
3. Growth regulators: Postharvest life of flowers can be controlled by growth regulators. Water relation changes associated with flower senescence are also influenced by growth regrlators. Cytokinins delay senescence of some cut flowers. Depending upon the concentrations, GA in some cases promotes longevity of flowers, while this is also used in bud opening solution. The IAA promotes ethylene production of isolated carnation petals. In contrast, the senescence and abscission of poinsettia flowers is delayed by auxin.
4. Preservative solutions: Preservatives in the form of tablets or powder are prepared from a mixture of chemicals-sugars, germicides, salts and growth regulators. Various types of conditioners are sugar and biocide, antiethylene compound, and hydrated compound. The flowers like gladiolus, carnation, chrysanthemum and freesia are benefited most by the pretreatment. Antiethylene compounds in preservative solutions reduce the action of ambient ethylene as well as autocatalytic production of ethylene by fresh cut flowers. Fresh cut flowers responding to silver thiosulphate are carnation, orchids, gypsophila, gladiolus, gerbera, snapdragon, alstromaeria, agapanthus, anemone and sweet pea. Greatest improvement in cut flower quality and longevity is obtained when DICA or DDMH were combined with sucrose.
5. Precooling and storage: Precooling is essential for removing field heat from flowers. This is done either by forced air cooling or hydrocooling to bring down temperature from 20⁰-30⁰C to 1⁰C in a relatively short period. Other methods are room cooling and vacuum cooling.  Flowers can be stored for a longer period at low temperature. There are two methods of cold storage-wet and dry. Wet method is short-term storage, in which cut stems are dipped in water. Dry storage is more labour-intensive method and costly. The controlled atmosphere based on reduction of respiration rates, conservation of respirable substrates during, storage, and delay in ethylene-triggered changes cause senescence. It involves the use of increased level of CO₂ and decreased levels of O₂ in the atmosphere, low storage temperature and prevention of the build-up of endogenous ethylene.
6. Packing and transporting: Packaging ensures garden fresh of flowers to the consumers. Lower rate of transpiration, respiration and cell division during transportation, are essential for long storage life and keeping quality. Before packing, flowers should be dried. They should be treated with systemic insecticides and miticides Packing must ensure protection of flowers against physical damage, water loss and external conditions detrimental to transported flowers. Boxes made of corrugated fibre boards are good. Flowers sensitive to geotropic bending must be transported in an upright position. The flowers should be transported at an optimal low temperature. The relative humidity of the air during precooling and shipment of cut flowers should be maintained at the level of 95-98%. Lack of light during prolonged transportation particularly at high temperature causes yellowing of leaves in many flowers. Shipment of flowers is usually done by truck, air and sea. For short distance and time period shorter than 20 hr, cut flowers may be transported in insulated trucks without regrigeration after precooling and proper packing. Air shipment is quickest and usually the temperature is not controlled during the flight The flowers should be pulsed with STS prior to air shipment  

 REFERENCES

Report of the all India seminar on potential and prospects for protective cultivation held at Ahmednagar from 12 - 13 December, 2003 pp 72-76.

Arora, J.S. and K. Singh. 2002. Pre and post harvest management of cut flowers. J. Indian Horticulture, 20-23. Chadha, K.L. 2000. Post harvest management of flowers. Hand Book of Horticulture. I.C.A.R, New Delhi, pp. 969-981.

Singh, M.K., S.R. Voleti, S.R. and S.S. Sindhu. Post harvest handling and care of cut flowers. J. Indian Horticulture, 44-45.

 

 

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