स्ट्रॉबेरी की वैज्ञानिक खेती
With the increasing awareness about the neutraceuticals and importance of fruits, consumers’ demand for fruits having higher levels of antioxidants, vitamins and minerals is increasing. Strawberry (Fragaria × ananassa Duch.) is one of the fruit which is high in neutraceutical properties; therefore it is sold at premium price in the market.
Strawberry is one of the most important soft fruits giving high returns per unit area in minimum time period. Though it is a temperate fruit crop but with the development of new cultivars, its cultivation has extended to sub-tropical areas also.
In India, strawberry is cultivated in Maharashtra, Haryana, Punjab, Himachal Pradesh, Uttrakhand, West Bengal, Jammu and Kashmir and North Eastern states. Besides the fresh consumption, strawberry fruits are used in the preparation of processed products like jams, jellies, spreads, ice creams and wine.
Soil and Climate for strawberry:
Although strawberry can be cultivated on wide soil types but for commercial production, well drained medium loam soil having pH 5.7-6.5 is considered the best. Presence of high calcium in the soil causes yellowing of leaves. Since roots of strawberry plants are mainly concentrated on top 15 cm of soil, therefore soil should be rich in humus.
Fields on which crops like tomato, potato, brinjal and pepper are grown during previous season should be avoided for strawberry cultivation. Runners are planted prior to the onset of the winters.
Plants are very much affected by environmental factors like temperature, photoperiod and day length. In areas experiencing cold climatic conditions, frost as well as winter injury affects the plants and can reduce yield considerably.
Strawberry Cultivars:
There are large number of cultivars of strawberry which can be cultivated from sub-tropical to temperate regions. Therefore, prior to taking up at commercial levels, different cultivars should be evaluated for its performance for their area specific suitability.
The important strawberry cultivars include Chandler, Camarosa, Sweet Charlie, Sweet Sensation, Albion etc.
Strawberry Planting:
In the regions which do not experience high temperature during summer months, strawberry plants produce runners during July-August. These runners are used as propagating material for strawberry cultivation.
Healthy, disease free runners having medium to large sized crowns with well developed root system are planted in 15-20 cm raised hill row system as single or double rows. Row to row spacing is kept at 90-120 cm and plant to plant distance is maintained at 30-45 cm.
Utmost care should be taken while planting strawberry because if crown is kept too high outside the soil, it will dry off and will be smothered if set too deep in the soil.
Therefore, crown of the runner should be set in the soil up to its middle portion. Exact time of planting is area specific depending upon the local agro-climatic conditions which varies from mid September to mid October. Planting during the October month is considered best for strawberry cultivation in open conditions.
Mulching:
Mulching is very important in strawberry cultivation as it protects the plants from low temperature during winters, reduces weed growth and protects fruits from touching the soil. Mulching with black or double coloured polythene sheets has yielded good results.
Irrigation:
Since it is a shallow rooted crop, therefore frequent light irrigations are beneficial as compared to little heavy irrigation. High soil moisture is detrimental to fruit yield as it increases incidence of different types of rots. Drip system is also considered good for strawberry irrigation.
Nutrient management:
Application of 25-50 tonnes FYM, 75-100 kg N, 40-120 kg P2O5 and 40-80 kg K2O for one hectare is recommended for strawberry cultivation; however, dose may depend upon soil conditions. Phosphatic fertilizers should be incorporated in the soil before planting strawberry in the field. Nitrogenous fertilizers are applied in two split doses; half dose three weeks after planting and second half dose at the time of flowering. Potash is applied only at the time of flowering.
Harvesting and yield of strawberry:
Strawberry fruits are harvested when 50-75% fruit area develops colour. Fruits are harvested along with calyx having 1-2 inches stalk intact. During the peak harvesting period, strawberry is harvested daily or on every second day. Though under ideal conditions strawberry yield can be higher, yet a yield of 20-25 tonnes per hectare is considered good.
Post harvest handling:
Strawberry is a climacteric fruit, so after maturity it ripens very fast and can get spoiled very easily. Therefore, storage of strawberry after harvest is not recommended due to it’s perishability. Harvested fruits are packed in plastic punnets and placed in corrugated trays for sufficient ventilation.
Pests and diseases:
Following are the important pests and diseases of strawberry:
1. Verticillium wilt: The older leaves start turning brown and get shriveled and in later stage plant dries out. For management, crop rotation should be adopted and soil should be fumigated with Formaline or Chloropicrin.
2. Leaf spot: Different types of leaf spots appear on the strawberry which result in drying of leaves and plants. Application of 0.05% Carbendazim at 15 days interval or 2-3 sprays of 0.05% Hexaconazole check the disease.
3. White grubs and cut worms: They cut the root and stem of the plant and can be checked by deep ploughing and soil drenching with 0.2% Chlorpyriphos.
4. Root weevil: They make tunnels through plant crown resulting in drying of the plants and can be controlled by treating the soil around plant with 6-10 kg/ha Carbafuran or 0.017% Methyl parathion.
Authors
Nirmal Sharma, Sanjeev K. Chaudhary, Neeraj Kotwal, Manoj Kumar
Regional Horticultural Research Sub-station - Bhaderwah, SKUAST-Jammu (J&K)-182222.
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