ABSTRACT and CONCLUSION
Structural construction to set up training systems of grapevines involves high costs in setting up vineyards in southern and western Indian vineyards.
Overhead trellising is a common system in that region to strongly support the vines which are highly vigorous due to varieties, climate, and lack of dormancy of vines. In the north Indian vineyards, no special structure is built up to support the vines which are not vigorous but their productivity is less. In the present article, the erection of a training system going by the name, Telephone system and mode of its use has been described. The method would be suitable for many varieties in the southern, western, and north Indian conditions.
The horticultural practice of "training" is done to a fruit plant to impart a desired size, shape, or form to it with the objective of enhancing the productivity and quality of the produce. In a fruit plant like a grape, this is of special significance as the plant being a vine necessitates support to grow. An ideal system of training in grapevines should beyond doubt, pay heedful attention, particularly to the following aspects. (i) It should make adequate exposure of the foliage parts to at least 75 percent. (ii) Facilitates easy pruning of branches. (iii) Enables uninterrupted growth of shoots. (iv) Does not cause difficulty in irrigation and cultural operations. (v) Intercropping, if needed can be done effectively. (vi) Facilitates easy harvesting. (vii) Makes the structural framework of the system strong and (viii) Does not involve high expenditure in setting up of the structure. There are in fact, various systems of training that are practiced in different grape-growing countries in the world, and each of them has merits and demerits.
Under Indian conditions, overhead trellising has been a common practice in the vineyards of south India. It is set up by posting pillars on the ground and making a network of roofing over them with thick and strong galvanized iron wires and the vines are crept on the net roof. The vines growing there being highly vigorous, need adequate support and hence, this system is followed. For vineyards in northern India, the grape growers adopt methods by which a vine gets the support by itself, and trellising to provide support is not done as the vines are less vigorous. Both the methods although considered befitting according to the climatic conditions and the varieties grown, have some demerits. In many parts of the southern and northern Indian conditions, a system of training, known as the Telephone system has, however, greater suitability in many vineyards. The system may be set up in the following way.
Method of installation
To make the framework, angle-iron rods of 1.0 2.0 metre length should be taken and at one end of each rod, two holes are to be made with a drill. The upper hole of about 2 cm diameter should be made at 36 cm below the edge while the lower hole of 1.5 cm diameter should be made at 4 cm below the upper hole. The rods are to be vertically posted maintaining a spacing of 5 metres towards the direction of the rows of the vines to be aligned (Figure 1). To do this, the end of each of the unholed sides of the rod should be embedded in a concrete platform of about 30 cm square foot area raised to 20-30 cm from the ground.
Now, for each embedded rod, two pieces of 60 cm long iron strips are to be taken. At each end of the strip, a hole should be made, the diameter of which should be the same as that of the upper hole of the rods. At the other end of each strip, another hole of 1 cm diameter should be made. The large hole made in the strip should be brought to a rod and this is matched with the upper hole of the rod. At this position (Figure 2), the strips are to be fixed with the rod by nuts and bolts, maintaining an angle of 160°. In this way, each rod should be fixed with two strips on either side, so as to look like the English letter, “Y”.
The galvanized iron wires of 10 gauge should then be passed, one through the lower holes of the rod and one each through the outer holes of each strip (Figure 3). Thus, the three wires will run parallelly and the central wire will be at the lower end. The setup looks like telephone lines and hence, is termed a Telephone system of training. The length of the lines should preferably be less than 23 metres but if exceeds, a gap of 3 metres should be left.
When the structure has been set up, rooted cuttings of grape are to be planted just below the central wire, maintaining a spacing of 1.5 metre. The plants are to be provided with stakes to grow straight. Within 6-7 months of growth when they will reach the central wires, they are to be pinched at the tips. In doing so, many branches will arise just below the tips, and among these, three well-spaced ones are to be retained while the rest are to be cut back at their bases. These three branches should be made to creep respectively on each of the three wires and in the same direction. When mature, these branches will, therefore, serve as the three arms of a vine (Figure 4) and from these, new shoots will arise which will bear flower clusters. However, when an arm grows to 1.5 metres, it should be pinched at the tip so that it does not extend further and overlap with the arm of the next vine.
Advantages
Among other benefits of the system, the following are particularly mentionable.
(I) Unlike the overhead trellising system or the head system, much greater exposure of the foliage parts, flower, and fruit clusters is ensured.
(ii) Spraying can be done with much convenience. In fact, while moving between two rows, the person can do the operation in the vines of the adjacent rows at the same time and for this, it can be done in much less time. Also, the spray material is able to reach all the foliage parts, ensuring thorough coverage.
(iii) Harvesting of fruit bunches can be done from the vines of two adjacent rows at the same time while moving between them and hence, saves time. (It may be brought to notice in this connection that the Telephone system of training may be of two categories, which are of "T" and "Y" types. In the former type, the three wires are made to run at the same level, like the English word, T, while in the latter type, which has been described above, the central wire runs at a lower level than the side wires and thus, the three parallel wires look Y-like appearance. Unlike the T-type, easiness in spraying and harvesting can be done in the Y-type only).
(iv) For varieties that are highly vigorous, the overhead trellising system may be suitable to support the heavy weight of the vines, but for moderately vigorous varieties, like Thompson Seedless, the Telephone system is highly suitable. In fact, some grape growers in Maharastra have adopted this system now and secure good crops.
(v) Intercropping can be done effectively in this system.
(vi) As compared to overhead trellising, installation cost is much less in this system.
