By Qazi Azam Riaz, Mujahid Ali, Dr. Rashid M. Balal
Horticulture, College of Agriculture, UOS
In history grapes are famous for wine making. It is mentioned in the Holy Quran several times. Grapes (Vitis vinifera) belonging to the Vitaceae family, originated in Western Asia and Europe. It was introduced to India by the Persian invaders in 1300 A.D. Grapes is a non-climacteric fruit that grows on the perennial and deciduous woody climbing vine. Grapes is a cross pollinated vine with simple, lobed, cut or toothed leaves (seldom compound) with racemes of greenish flowers, the fruit consisting of watery or fleshy pulp, stones and skin, four-seeded. Grapes can be eaten as fresh or used for making jam, juice, jelly, vinegar, wine, grape seed extracts and grape seed oil. Approximately, 71% of world grape production is used for wine preparation, 27% as fresh fruit, and about 2% is used as dried fruit. However, in Indo-Pak region, about 90% of the grape is used for table purpose, even though wine making has made strides. The rest of the grape is used mostly for raisin. Its cultivation is called viticulture.
Grapes occupy a predominant position in terms of world fruit production, accounting for about 16% of the global fruit production. The total world production of grapes is estimated to be about 68.9 million tons, next only to citrus and bananas and is followed by apples. The major grape producing countries are China, Italy, France, Spain, U.S.A, Turkey, Argentina, Iran, Portugal, South Africa and Chile.
Organic farming is a crop production method respecting the rules of the nature. It maximizes the use of on farm resources and minimizes the use of off-farm resources. It is a farming system that seeks to avoid the use of chemical fertilizers and pesticides. In organic farming, entire system i.e. plant, animal, soil, water and micro-organisms are to be protected.
The climatic factors such as temperature, occurrence of frost, rainfall and relative humidity play a vital role for commercial cultivation of grape. Generally grape requires a hot and dry climate. Regions with high rainfall and humidity is not conducive for grape cultivation. Hence the coastal districts of the state are not suitable for grape production. Grape is successfully grown in regions with a temperature range of 15°C to 40°C and rainfall of 50 to 60 cm. The weather should be clear for about 3-4 months during the cropping period. Cloudy weather, high humidity low temperature and rain during flowering and berry development are detrimental as they promote spread of diseases
Although grape can adapt to a variety of soils, it grows and performs best in deep medium-textured soils (loams and sandy loams) with good drainage and low salt content. Salinity is the major hindrance in the development of grapes. It grows well in soils with a pH range of 6.5 to 7.5. Development of salt resistant rootstocks like Dogridge and Salt Creek has given an impetus for area expansion under grape in saline areas. Most of the new vineyards are established on Dogridge rootstocks in the state of Maharashtra. The rootstocks are supplied by NRC Grapes, Maharashtra Grape Growers’ Association etc. Some of the progressive farmers produce rootstocks for their own use and sale. The mother plants are available with NRC Grapes and farmers’ field. The rootstocks are raised by planting hard wood cuttings on flat beds at desired spacing, depending upon the variety and method of training. The main varieties grown under organic cultivation in the state are Thompson Seedless, Sharad Seedless and Tas-A-Ganesh
For its cultivation spacing varies with variety and soil fertility. Generally, under organic cultivation, spacing of 2.5 m x 1.5 m, 2.75 m x 1.50 m and 3.0 m x 1.5 m are followed. For this model scheme, a spacing of 2.75 m x 1.50 m with a plant population of 2425 plants/ha is considered best. The land is prepared by ploughing it twice and harrowing it thrice. Pits having dimension of 90 cm x 90 cm x 90 cm are dug and filled with soil and well decomposed FYM or compost with 55 t/ha is used. The pits are then irrigated to allow the soil to settle down. Normally rectangular system of planting is adopted for growing grape.
Training/pruning is an important operation in grapes. It helps to maintain the stature and spread of the vine and facilitates operations like pruning, inter cultivation, spraying and harvesting. There are many systems of training. The common systems in India are Bower, Kniffin, Telephone, Trellis and Head system. Mostly Bower and Trellis system has been found to be the best for commercial varieties like Thompson seedless, Sharad Seedless and Tas-A-Ganesh. In Bower system, a bower of 2.1 m height is erected using stone pillars as support and galvanized iron wire of 8 and 10-gauge thickness for mesh. One vigorous growing shoot is selected by nipping off other shoots and this single shoot can grow up straight with the support of bamboo or plastic wire stake. All the axillary shoots are pruned, and the main growing shoot pinched off at 15 cm. Two shoots arising below the cut area can grow in opposite direction on the wires overhead. These two shoots develop into main arms. On the main arms, side shoots can grow at regular intervals of 40 to 45 cm. These side shoots are called secondaries and tertiaries or canes from which fruiting spurs develop. The arms and secondaries form the permanent frame work of the vine. The main arm should be trained towards East and West direction to reduce damage due to sunburn during summer months especially after February-March pruning. The entire space allocated for each vine is covered in a gradual manner by intermittent pinching of the primary arms and secondaries, not allowing them to grow more than 60 cm at a time. As they grow, the shoots are tied with jute twine and all tendrils are removed.
Removal of any vegetative part in a vine/tree is called pruning. It is a critical cultural practice in grapes cultivation. Therefore, much care and precision need to be exercised in pruning a vine. The main objective of pruning grapevine is to increase productivity, facilitate intercultural operations and maintain desired vine framework and vitality of the vine for consistent productivity. In organic grape cultivation, the vines are forced to undergo rest for about a month immediately after harvest. This helps in storing the food material in the mature parts of the vine. The canes are cut back in April by keeping 1-2 buds which develop into canes in 4-5 months. The removal of dried canes is called ‘back pruning’ or ‘growth pruning’. In the month of September-October these canes are pruned for fruiting. This pruning is called ‘forward pruning’ or ‘winter pruning’. Vines, which have attained the age of one year can be subjected to this pruning.
Manuring is done by applying FYM at the rate of 55 t/ha. Biofertilizers like Azatobacter, Phosphate Solubilizing Bacteria (PSB), Effective Microorganism (EM), Neem cake and vermiwash are being used to supplement the nutrient requirement of crop. Trichoderma, Azatobacter and PSB are applied at the rate of 25 g/plant. Neem cake is applied at the rate of 1.25 t/ha. Jeevamrut (organic pesticide) is prepared by adding 10 kg cow dung, 5 liters cow urine, 2 kg black jaggery, 2 kg ground pulses powder, handful of bund soil in 200 l of water. The solution is kept for 2 to 7 days in shade for fermentation. During the fermentation, the solution is stirred daily. To improve the quality of grapes, a solution of sugar, humic acid and coconut water is sprayed at bud development stage.
A fully-grown vine requires about 1000 liters of water in winter and 2000 liters in summer season immediately after pruning and application of fertilizer. Vines are given 2 to 3 summer irrigation at 3-4 days interval. During winter, an interval of 8-10 days is maintained between two irrigations. The vines are to be irrigated when the top 5 cm soil is dry in winter and 3.5 cm top soil is dry in summer. During berry development stage irrigations are given at weekly intervals and the same is withheld 10 days before harvesting to improve quality.
In the grapes orchard, weeding is usually done mechanically. Frequent weeding is obligatory to allow feeder roots to absorb the nutrients and moisture without any competition. Bullock drawn, or tractor drawn implements can be used for inter-cultivation and weed control. Weeding is done 3-4 times in a year. Shoot pinching is a part of pruning mainly done to promote fruit bearing and regulate the current season’s growth. This is done when the main shoot attains 7-8 leaf stage. During pinching, the tip of the mature shoot is pinched by retaining only five nodes. As a result, the terminal bud along with 1-2 laterals resumes growth. These laterals are called sub-canes. Buds up to the third node from the base on the sub-cane are observed to be bearing fruits.
The major pests affecting the grape crop are flea beetles, thrips, mealy bugs and leaf hoppers. The major diseases are downy mildew, powdery mildew and anthracnose. The Dasparni Arka is prepared by adding 25 kg leaves of Neem and 2 kg leaves each of custard apple, Nirgudi, Kaner, Cotton, Papaya, Castor, Karanj, Gudwel, Drumstick in 200 liters of water. In the solution, 5 to 10 l of gomutra and 2 kg of green chilies are added. The solution is kept for 15-20 days for fermentation. The stock solution is prepared by filtration through muslin cloth. The spraying is done by adding 5 l of stock solution in 200 liters of water.
Grape is harvested almost all the year round. If not all the varieties, one or the other variety is always available at any given time of the year. However, in Thompson Seedless and its clones, major part of the produce is harvested during March-April from the hot tropical region contributing to more than 70% of the total harvest. An average yield of 15 -20 t/ha is obtained during the second and the third year onwards which increases up to 25 t/ha from the fourth year onwards. The economic life of grape is fifteen years and harvesting of fruits can be done up to an age of 15 years. In Pakistan our major problem in Punjab is its continuous cultivation, due to moon soon season our autumn crop totally fail due to flower drop and different fruit diseases so, we need to draw attention of researchers toward its continuous growth.