| - By RAJ KUMAR MIRAKHUR Floriculture Consultant , Golden Petals, Pune |
One aspect which has been and is being paid little attention in commercial rose-growing in India is the crude handling of cut flowers after cutting. This leads to poor realization in the international markets. For sure, post harvest handling deserves a more important role in our farm operations. Most commercial rose projects lack proper supervision post harvest. Look at the harvested flowers in the grade room, and you will see more than 3 to 4 different stages of cut roses. This can be controlled only by proper and vigilant squad of supervisors at the greenhouse. We cannot blame the weather because temperatures are very moderate and there is plenty of time for harvesting.
Personally, I believe that the turnover in floriculture supervisors tends to cause a lot of problems and leaves no continuity in supervision. How many people know, for instance, that flowers should be removed from light as soon as possible so that the slitopening closes. Yet again some varieties are cut in the tight stage when the sepals loosen around the petals while others are cut when outer petals begin to unfold. |
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Very few growers set the harvesting stage with due attention to the variety, season (temperature during growing period) number of petals, or even the distance to the market! Harvesting Remember, flower tells you when it is ready for harvesting. And you must adapt the harvesting schedule around the flower, even if it means harvesting once or four times a day. Let me also share a trick of growing roses successfully under the climatic conditions in Pune and Gujarat regions - try and minimize the thin stems. One way to do this is to continually under-cut thin stems down to strong dormant eye besides the staggered pinching, leaving enough leaf surface on the bush to cope with this and allowing them to thicken before cutting for production. With the high ambient temperatures, cropping too high up the bush will give thinner and thinner stems - go too low, your production will be affected. This fine line between quality and quantity is always a hard one to define, and only real practical experience will give you the answers. Lots of problems originate from harvesting. Remember, harvesting is like continuous pruning. Where rose is cut dictates the quality of the next flush.
I feel it is imperative to repeat some salient principles put down in an earlier issue.
They are:
Identify the right cut stage
Always cut on to a mature "five-leaf"
Leave only maximum 1 cm wood above the cut
Harvest as frequently as the plant dictates - once, twice or even four times. Each variety has its specific cut stage,
and this must be stuck to
Get the rose as soon as possible into water and then under temperature control
Ensure that the water in the buckets is clean and at least contains chlorine at a concentration of 15 ppm. Preference would be given to proper grade of Florrissant generally used for roses
Do not force too many stems in the bucket; this is going to damage the stems and buds
Besides the above, it is always beneficial to wrap the cut stems with some wrappers - these could be polypropylene wrappers or even some old clean fertilizer bags - before putting them in the buckets. The idea is to reduce damage to buds by preventing any movement or rubbing of the buds against thorns. The wrapper also physically supports the stem, preventing bent necks. Also due to micro-climate contained within the wrapper, dehydration of the foliage gets reduced. Give it a try and see for themselves if they do improve things. It is desirable to cut/harvest all roses at the same cutting zone.
The harvest itself will be easier, and crop development under similar light levels results in a more uniform quality. During hotter periods, when the flower opening is rapid, some varieties will be cut even 3 to 4 times a day. Work of rose technologists Durkin and Boodles amply makes it clear that flowers are more fully hydrated in the morning than in the afternoon, but this advantage is countered by two problems: one, the morning cut is usually heavier and thus it requires more time; and two, water loss rates are much higher in the morning than in the afternoon.
Thus, it is at least likely that flowers will wilt during morning cut as during the afternoon cut. Problems to tackle There are several reasons besides proper harvesting that cut roses might not perform satisfactorily, but most come under one or several of the following; failure to control water relation, lack of adequate food supply for full development. Disease and microbe development in the vase solution. Water Water makes up about 85 % of the rose flowering shoot. On the plant water is supplied in needed quantities by the root system to replace water lost to the atmosphere. When the shoot is small, accumulation of water in the cell accounts for the pressure which produces cell growth and makes the shoot grow. For the tight rose, water is urgently needed for an identical purpose - to cause flower growth. More than 99 % of the water taken up by a rose shoot is sooner or later lost to the atmosphere. The main job of growers is to make certain that the soil water is replenished often enough to ensure a proper growth rate; the roots do the rest. If the continuity of water in the cut rose flowers is hampered or delayed, air may enter the water, conducting tissues or obstructing the movement of water. This results in greater water loss than uptake and always results in wilting.
Wilting prevents flower growth which may be followed by bent neck. Most of the water problems are manageable if the growers treat the freshly cut flowers with acidic solution before placement in preservative solution. In real sense, problems of water balance can be considered the single most important problem facing the rose industry.
Food
Food for the cut roses is stored within the rose at harvest, but one must realize that what is stored depends on the season, handling and time after harvest. No matter how well they are grown, roses benefit from preservative use. The preservatives contain sugar, the energy source. It also contains an acid for pH reduction, a germicide to reduce microbe growth. Hydration
It is very imperative to note that failure to manage hydration at the production area can lead to poor cut rose performance. There can be no doubt that other reasons exist for poor performance as well, but the effect of poor hydration too often masks them. Well grown roses which are properly hydrated after harvest should perform well in the marketing chain to the best satisfaction of the customer. It is thus very vital for a progressive rose grower to understand that post harvest handling must be the most important operation carried out on his farm. When a flower is harvested and before it is under temperature control, it is extremely sensitive to any stress. Adverse handling at that stage will have lasting consequences throughout the whole marketing chain.
Incorrect Cut Stage
As already emphasized, the flower has to be at a definitive stage of development to enable it to survive the physiological shock of harvesting and be sufficiently mature to open fully in the vase. If the flower is cut at the wrong stage it will affect the length of storing time. Also the more open the cut stage, generally, the higher the chance of damage in transport. In short the vase life of cut rose is affected by its cut stage. If it is too ripe it will blow too quickly and if it is too tight it won't fully open and is likely to wilt easily. In order to correctly understand the problems, we must remember what serious influence the harvest has on further development of a rose. Before harvesting, the cut rose is a part of an intact plant, well supplied with light and air. The root system is in a position to supply sufficient water and nutrients for all functions. But when a flower is cut, the level of carbohydrates drops rapidly due to continuous respiration. This reduces the ability of the flowers to absorb sufficient water and the cells begin to dry out. A flower grown under stress will not have necessary vase life due to deficiency of the sugars. A common cause of this shortened vase life is too high temperature.
What Influences Quality
Too long a time between cutting and bringing the flower under temperature control (it will continue to open before it goes on to be graded)
Cold store fluctuations badly ventilated or dirty cold store and low humidity
The grower should possess a thorough understanding of why flowers are kept in the cold store. Basically, it is done
to decrease the water loss
to slow down the overall metabolic rate of the flowers
to inhibit bacterial growth
to allow the grower to bulk up the volumes for efficient handling
because too long a time is spent in processing, grading and sorting in a grading facility with too high a temperature
because too many open flowers are stored in the cold store. [Even if there are just one or two stems in a bunch that are too open, they will be emitting high levels of ethylene, which in turn will have an affect on other flowers in the box]; and
because the healthier and stronger the stems are harvested, the more likely it is to hold at its required cut stage and eventually get better realization in the market
Negative Effect
There can be some negative effect of long storage on the ultimate vase life of cut roses. Even though the metabolic rate is reduced to minimum, there are some chemical reactions, mainly involving certain enzymes, that are more temperature-sensitive than others and this causes a terrible imbalance in the plant physiology, thus shortening the vase life. It is also important not to loose sight of the complications of fungal infections, such as Botrytis, when storing at high relative humidity. Botrytis spores are everywhere in the green house and if you give them the congenial conditions they will infect your produce quickly.
Grading, Sorting & Handling
Mostly everyone gets a shock to see the state of his product on arrival at the point of destination (in the importing country) compared to how it left the farm. All handling operations from harvesting to packing must be studied continually to find practical ways of reducing the amount of time the product is manhandled for. Every time the product is picked up or moved or packed it experiences some damage, however little. The grading and sorting is market-specified, as each market requires its own specific package. Grading/sorting is basically about forming uniform packages of flowers in correct quantities, qualities and cut stages to meet the market demands. You don't really create the quality in the grading shed, the quality is predetermined in the green house. However, the better the quality in the greenhouse the quicker and easier the grading and sorting becomes. The purpose of grading is to take out the worst quality so that it does not affect the price of the best quality. If the qualities are mixed, the price paid is equivalent to the worst quality stem in that package.
Uniformity
Uniformity is probably the most important word to bear in mind in all grading and sorting operations. The market is obsessed with uniformity; they want well presented uniform packages, as they are available from other competitors, so you should do it as well or even better than that.
Working Envoirnment
Of vital importance in the whole operation is the cleanliness and tidiness of the working environment. There are not only physiological reasons but also practical reasons to ensure cleanliness. Rotting vegetation (leaves, stems, flowers, etc) in the grading and cold store creates high levels of ethylene that adversely affects cut stage and maturation of the flowers. Dirt dropping into water can block the vascular system and it can also create a media for bacteria to breed on.
There are normal precautions to take, such as scrubbing the floor, and the tablets with biocides such as chlorine, cleaning the buckets, tables, scissors and scrubbing out the cold store. Nothing is too much. If all this is done properly, then your product will be in the best possible condition to survive not only the unpredictable freight schedules but even more important unpredictable markets. The net result would be better realizations per stem and the grower would be the ultimate winner. |
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