Harvesting is the operation in which the tender tea shoots are picked, which generally termed as “plucking”. A tea shoot at the correct maturity for the manufacture of high quality made tea, comprises of an unfurled bud with two or three soft leaves.
The correct proportions and concentrations of chemical compounds and enzymes which synthesize poly-phenolic structures in made tea, occur in fresh tea leaves at that correct maturity.
On the other hand, hard fibrous parts in tea shoot is getting higher with the maturity. If the shoots are over grown, it will sure decrease the out turn and increase waste tea in manufacture. The quality and the quantity of made tea will be, thus, determined by the maturity of the shoots being plucked.
Therefore, it is extremely important to strictly adhere to the correct maturity of tea shoots as it determines the quality and the quantity of the made tea and hence, the profitability of the tea plantations.
Thorough understanding on the severity, standard and interval of tea harvesting will be resulted in high quality fresh shoots being plucked. These terms will be clearly discussed, later in this page.
Most of the tea farmers or land owners practice manual harvesting. Being the most labour intensive practice consuming approximately 50%-60% of the total labour requirement in tea field operations, harvesting contributes about 25%-30% of the cost of production (COP) in Sri Lanka.
Mechanical harvesting appears in practice when the labour scarcity is experienced. Though it is apparently increases the labour productivity, it highly affects the productivity of the tea bushes and quality of made tea in tropical countries where a well distributed rainfall and year-round sunlight received. The main reason for this kind of consequence is non-selective harvesting which ruins the tea bush by affecting sink source connection of the carbohydrates produced in the leaves.
Handling and care of fresh leaves after harvesting is as important as the correct maturity for the quality of made tea and profitability, since careless handling and transport will add impurities and damage the green shoots before they are manufactured and thus, increase post harvesting losses.
Therefore, better understanding about the physiology of tea shoot and post harvest handling and care of fresh leaves will be utterly important for quality made tea and profit maximization.
Wednesday
Parts of a tea shoot or Physiology of a Tea Shoot
In any plant, there are two kinds of buds or shoots. Buds at the top of the branch or shoot is called the “Apical bud” and below that between every petiole and the stem, are alternative or side buds.
So long as the apical bud or the top most bud is there, all other minute alternative or side buds tend to inactive and remain silently without growing. This phenomenon is so called as the “Apical Dormancy”.
When a shoot is picked, the apical bud is removed and hence, the apical dormancy is beaked, allowing the bud immediately below the plucking point to get active and grow, which is termed as bud break. Most of the time, only one bud immediately below the plucking point begins to grow, some time that might be two or three.
First two scale leaves covering and protecting the minute buds are opened with the swelling of that minute shoots. Then the shoot becomes growing fast and the first leaf or the Fish Leaf (Mean Leaf) is unfurled. Fish leaf is different from the normal tea leaf by its small size, absence of the serration in leaf margin and blunt leaf tip. Rarely, there might be two such leaves opened. In such instances the below one is called the Janam leaf while the upper one is termed Fish leaf.
Then the normal leaves unfurl and grow rapidly. Once a new leaf is unfurled the weight of the shoot is doubled. But this rapid growth remains only about 2 – 3 leaves unfurled. After that, though the shoot is growing the weight gain is less and the same time, fibrous content and hardy parts become the main constituent of the weight. After producing approximately 5-6 leaves, the apical bud becomes inactive and stops growing. This plant specific, genetically controlled phenomenon, having two alternative periods of active and dormant is technically termed as the “periodicity of growth” or “growth periodicity”.
Once become dormant, it will take approximately 3-4 months to get active and grow if remained un-plucked after which it get active & grow again. If the dormant shoot is plucked, it will begin to grow once the apical dormancy is removed and again produce a harvestable shoot around 40-50 days.
So long as the apical bud or the top most bud is there, all other minute alternative or side buds tend to inactive and remain silently without growing. This phenomenon is so called as the “Apical Dormancy”.
When a shoot is picked, the apical bud is removed and hence, the apical dormancy is beaked, allowing the bud immediately below the plucking point to get active and grow, which is termed as bud break. Most of the time, only one bud immediately below the plucking point begins to grow, some time that might be two or three.
First two scale leaves covering and protecting the minute buds are opened with the swelling of that minute shoots. Then the shoot becomes growing fast and the first leaf or the Fish Leaf (Mean Leaf) is unfurled. Fish leaf is different from the normal tea leaf by its small size, absence of the serration in leaf margin and blunt leaf tip. Rarely, there might be two such leaves opened. In such instances the below one is called the Janam leaf while the upper one is termed Fish leaf.
Then the normal leaves unfurl and grow rapidly. Once a new leaf is unfurled the weight of the shoot is doubled. But this rapid growth remains only about 2 – 3 leaves unfurled. After that, though the shoot is growing the weight gain is less and the same time, fibrous content and hardy parts become the main constituent of the weight. After producing approximately 5-6 leaves, the apical bud becomes inactive and stops growing. This plant specific, genetically controlled phenomenon, having two alternative periods of active and dormant is technically termed as the “periodicity of growth” or “growth periodicity”.
Once become dormant, it will take approximately 3-4 months to get active and grow if remained un-plucked after which it get active & grow again. If the dormant shoot is plucked, it will begin to grow once the apical dormancy is removed and again produce a harvestable shoot around 40-50 days.
Generations of Tea Shoots
Now you will understand that there are many shoots in a tea bush in productive age, in different stages or maturity in growth. These are shoots that still not emerged, shoots with only two scale leaves, bud with one leaf, two leaves, three leaves and so on. A group of shoots at the same maturity is called a generation. Therefore, in a tea bush trained to pluck is having 6-7 shoot generations, which we harvest the oldest one or two generations, remaining the rest un-plucked, to be plucked in next plucking as heavier units.
Now you are clear that, for continuous plucking and growth of new shoot generations, picking of older shoots is necessary. To ensure the quality of made tea and an acceptable out turn, shoots are plucked at the correct maturity at, bud with 2-3 leaves, at which stage the chemicals in leaf cell sap and the fiber content is in the correct proportion for a quality and supreme made tea manufacture.
Now you are clear that, for continuous plucking and growth of new shoot generations, picking of older shoots is necessary. To ensure the quality of made tea and an acceptable out turn, shoots are plucked at the correct maturity at, bud with 2-3 leaves, at which stage the chemicals in leaf cell sap and the fiber content is in the correct proportion for a quality and supreme made tea manufacture.
Plucking interval or Harvesting interval
When the oldest one or two generations are being plucked, it will take about 5-7 days (in tropical countries) for the next generations to come into the plucking stage. This time of 5-7 days between 2 consecutive harvestings is termed the “plucking round” or “plucking interval”. Scientifically, the plucking round is preferably the same as the “leaf period” or “shoot phyllochron”; the number of days taken for fully unfurling of leaf from the bud.
Severity of plucking
The tea bush is well trained so that the top of the bush is flat or dome shape to allow equal sunlight without mutual shading among shoots. Such flat well trained surface of tea bush is called the plucking table.
Depending on the climatic and weather conditions, the shoot growth also changes. In monsoonal periods where both adequate rainfall and sunlight is available shoots tend to grow very fast. Other cultural practices such as pruning, new planting, infilling, fertilizer application, tipping, etc. must also be done in other fields where necessary. Due to the rapid growth, more labour demand takes place for plucking as well as for other cultural practices.
In such periods which is termed as the “Rush Crop Season”, it is necessary to pick shoots at the point just above the fish leaf, which is termed as “fish leaf plucking”. This severity of plucking is termed a “hard pluck”. This is important in maintaining the height of the plucking table. When the climatic conditions are not favorable, such as in droughts, plucking is done remaining the first normal leaf to the canopy. This leaf is nourishing the newly emerging shoot and hence, called the “mother leaf”. The severity of such plucking is termed as a “fine plucking or mother leaf plucking”. When fish leaf plucking is practiced, the fish leaf remained on the plucking table is working as a mother leaf to the new shoot.
For maintaining a good photosynthetic action, adequate to maintain the bush, it is requited to maintain at least 25 cm thick top leaf layer. Older leaves below that layer won’t contribute much to photosynthesis as they are older and mutual shading from upper layers.
Tea leaf become its highest photosynthetic rate at half of its mature size approximately in six 6wks from unfurling, and remain in that rate approximately 6 months. After that it will remain about 18 months in the canopy but the contribution to the photosynthesis is considerably low. Therefore, adding new leaves to the canopy is compulsory for favorable carbohydrate assimilation for better and vigorous maintenance of the tea bush.
This will make your understand correctly that alternate fine and hard plucking systems must be practiced in favorable and less favorable weather periods.
Standard of plucking or Plucking Standard
For a high quality made tea manufacture while increasing the out turn it is necessary to pluck only the shoots at the correct maturity. Only buds with 2 or 3 tender leaves and tender dormant buds are accepted for the manufacture. If the proportion by weight of above three categories of shoots are >75%, it is called a fine plucking standard (Of course, fine plucking severity helps to get a fine plucking standard), if it is 75%-60%, it is considered a medium plucking standard while <60%>
Subscribe to:
Posts (Atom)