Strawberry is very delicious and nutritious fruit with a sweet flavor and pleasant aroma. Strawberry is rich in vitamins and minerals particularly iron. Strawberry is best suitable for raw consumption. Strawberry fruits are also used for preparing strawberry jams and syrups. Strawberry is cultivated as a temperate fruit crop in India and it can be grown throughout the year. In India, strawbeery is commercially cultivated in Nilgiri hills, Uttarakhand, Himachal Pradesh, Punjab and Haryana. Strawberry prefers a temperate climate for its vegetative growth. Twelve hours of daylight period is preferred for its flower bud inititation. But this requirement of daylenght may differ from cutivar to cultivar. Generally moderate temperatures are preferred by strawberry plants.
Major strawberry cultivars that are grown under septentrional climatic conditions (that is, short day lenghts in autumn and severe winter conditions) are Senga Sengana; Gorella and Redgaunlet. An important strawberry cultivar that is best adapted to meridional climatic conditions (that is, long daylenghts in autumn and moderate winter conditions) is Tioga. Day-neutral cultivars of strawberry include Hecker, Tristar, Silva, Fern, Muir, and Trileute. Day-neutral cultivars of strawberries are among high yielding strawberry varieties.
Soil Requirements for Strawberry Cultivation
Strawberry plants can be cultivated both in rich and poor soils, provided that soil is prepared well adding organic matter and other essential nutritents required for the plant growth well ahead of planting. Well-drained soils are best for strawberry cultivation. Since root development is mostly taking place in the top layer of the soil (approx. 15 cm), this root region must be rich in humus. Slightly acidic to neutral soils are favored by strawberry plants. Root development is restricted at higher pH. In short, well-drained, loamy soils having a pH between 5.5 and 6.5 are ideal for strawberry cultivation.
Promising Varieties of Strawberry
This is a strawberry with bright red color and strong flavor. Chandler strawberries are resistant to damages caused by rain and plants are higly resistant to viral diseases. These strawberry fruits are equally good for raw consumption and processing. Chandler strawberry is very large and each fruit weighs approx.15 to 20 gm. Nutritional value of chandler strawberry is very high with 12% TSS, 0.85% of acidity, 55.5mg/100g of Vitamin C and 6.1% of sugar.
Tioga is an early variety of strawberry. Tioga strawberries are large and juicy with firm skin. Hence these are suitable for dessert and processing purposes. As far as nutritional values are concerned, tioga strawberries contain 12.2% TSS, 0.98 - 1% acidity and 6.2% sugar content. Each tioga strawberry weighs about 9-10 gm.
Torrey strawberry plants are very tough and highly resistant to plant viruses. They produce large good quality fruits which are suitable for both dessert and peocessing purposes. Each fruit weighs approx. 7 gm. Torrey strawberries contain 12 % TSS, 0.98 - 1% acidity and 6.2% sugar content.
Fern is a day-neutral cultivar of strawberry. It is an early ripening variety. Fern strawberries are large, bright red with excellent flavor and aroma. Fruit skin is firm and fruits are fleshy. Each fern strawberry weighs around 20-25 gm. Fruits contain 11 % TSS; 0.88 % acidity and sugar content 6 %.
Belrubi strawberries are large and conial in shape. Each fruit weighs around 15 gm. Fruits contain 11.8 % TSS; 0.98 % acidity and sugar content 6 %.
Selva is also a day-neutral variety of strawberry. Selva strawberry plants produce berries even during off-seasons. It produces large fruits with firm skin and good dessert quality which can endure long distance transportaion. Hence these strawberries are best suited for exports. Each individual selva strawberry weighs around 15 to 20 gm and contains TSS 11 %, acidity 1 % and sugar content 5.5%.
Pajaro strawberries are susceptible to rain damage, resistant to plant viruses and good to grow under summer system. Each fruit weighs approx.7.5g, with TSS content of 12.2%, acidity 0.97% and sugar content of 5.5%.
Other commercial cultivars of strawberry are Bangalore, Florida 90, Katrain Sweet, Pusa Early Dwarf, Premier, Red Coat, Local Jeolikot, Dilpasand, Blakemore, Olympus, Hood and Shuksan
Olympus, Hood and Shuksan are best suited for ice-cream making, whereas Midway, Midland, Cardinal, Hood, Redchief and Beauty are quite suitable for processing.
Propagation of Strawberry Plants
Vegetative propagation through runners is practiced for commercial cultivation. Every strawberry plant produces up to 10 - 15 runners under proper plant management practices. Another propagation method is by division of crowns of oldr plants. Seed propagation is not suitable for strawberries.
How can runner production be stimulated?
Use IBA @ 100ppm or Morphectin @50ppm approx. 10 days before flowering.
Precaution before Planting
Since viruses and nematodes are serious problems for strawberry cultivation, care should be taken while procuring planting materials. Procure only virus-free planting materials for commercial plantations. Raise these plants in fumigated soils to control nematode problems.
Tissue Culture for Strawberry Propagation
Tissue culture is widely practiced for comemrical progapagtion of virus and nematode free planting materials for large scale cultivations. Plant parts that are mostly used for tissue culture are meristem and meristematic callus, anthers and other reporidctive parts and young, immature embryos.
Cultivation Practices for Strawberry
Soil preparation starts during summer by repeated ploughings of the land. Once soil is prepared, it is fumigated using a mixture of methyl bromide and chloropicrin.
Planting of Strawberry Plants
In Indian hilly areas, ideal time for planting strawberry runners or crowns is September–October. Runners soon get established in the main fields under proper nutrition management. Mature plants start yielding fruits during following spring season.
Runners or crowns are raised in the nursery and the main field is prepared before planting begins. Nursery-raised runners or crowns are uprooted carefully and immediately transported to the main planting sites. A small pit is dug manually and a small bundle of runners is placed into the pit with care. Soon after planting, runners are irrigated adequately.
Training of Strawberry Runners
Training systems that are followed in India are matted row, spaced row, hill and plastic mulch.
In matted row training system, runners are planted at a spacing of 60cm × 25cm. During first year of vegetative growth, newly produced runners are allowed to grow and cover the vacant spaces around mother runners and thus giving a mat like appearance. The advantage of matted row training system is that it does nto allow weeds to grow and also more number of plants per unit area can be accommodated while planting. This inturn helps higher fruit yield. But care must be taken to avoid overcrowding and fruit rot.
Spaced row training system is best suited for those strawberry varieties that are weak in producing runners. Selected tips of the mother plants are covered with soil at definite distances in order to boost the production of sufficient number of daughter plants in spaced rows. Thinning is done when extra vegetative growth happens.
Hill system of training is best suited for those plants that produce a few runners. All these runners are removed from mother plants and planted individually at 25 to 30 cm apart in twin rows that are one meter apart.
In plastic film training system, plastic mulch is used, after the planting of strawberry runners, for weed control and moisture conservation.
Manuring and fertilization
For Himachal Pradesh hills, the recommended fertilization procedure is to apply 50 metric tonnes of farmyard manure (FYM) and 40kg each of P2O5 and K2O/ha at the time of soil preparation. 80 Kg of N should be applied in 2 equal doses, first in October after the establishment of plants and rest just before blooming.
For Uttarakhand hills, 25 – 50 Kg FYM (at the time of soil preparation); 75 – 100 Kg N; 80 – 120 Kg P2O5 and 50 – 80 Kg K2O must be applied. Nitrogen is applied in equal doses. First dose is given one month after planting and second dose is given at the time of flowering. Full dose of phosphorus and half dose of potash is given at the time of planting by placing the fertilizer at a depth of 15 cm between the rows. Remaining potash dose is given at the time of flowering.
Four Foliar applications of liquid fertilizers (containing 0.5% N, 0.2 % P2O5 and 0.5 % K2O) during August to February is also recommended for all strawberry growing areas.
Removal of reproductive growth or flower buds is necessary until plants get established in the fields. Weeds must be controlled regularly as weeds may hinder honey bee pollination.
Strawberry is a shallow rooted plant and hence frequent irrigation in small quantities is an absolute necessity. The space between the rows are irrigated and while irrigating care is taken not to wet the plants. Irrigation is an ongoing process until fruits are harvested. Trickle irrigation and sprinkler irrigation methods may also be used for irrigating strawberry plants.
Ideal harvesting stage is when half to three-fourths of fruit skin develops red colour. Harvesting is done manually in early morning at every second or third day. Harvesting duration varies from one to two months depnding on the variety. While harvesting, fruit along with a small portion of stem is picked. Fruit yied varies from 50 – 200 Q/ha depending on the variety.
How to increase fruit yield?
Apply GA3 (50ppm) and maleic hydrazide (0.1–0.3%), 4 days after flowering. It increases fruit yield up to 40 %. Application of Morphectin (50ppm) increases the size.of the berry.
Precooling of strawberries at 4°C within two hours of harvesting is necessary for the preservation of fruit quality. For distant markets, fruits must be kept at the same temperature in reefer vehicles. Strawberries can be stored up to 10 days in cold storages.
Albinism or lack of color (white or pink fruits instead of red fruits) is a major physiological disorder in strawberry. This is mainly because of erratic climatic conditions and nutritional deficiencies.