तरबूज संकर बीज उत्पादन तकनीक

Watermelon (Citrulus lanatus Thumb) is an annual vine crop. It is grown throughout tropics and subtropics. It is monoeceous bearing male and female flowers separately. Flowers are mostly borne single. Anthesis starts at 6.00 am and completes at 7.30 am. Anther dehiscence starts one hour before anthesis and continue upto 7.00 am. At high temperature stigmatic fluid starts drying stigma becomes non receptive by 3.00 pm.

Hybrids of watermelon:

Arka Jyothi from Indian Institute Of Horticultural Research Madhu, Milan and Mohini from Indo-American Hybrid Seed Company, NS 295 from Namdhari seeds Kushboo, Madhubala, Sitara from Nunhems Seeds Kirana, Mithila and Madhumita from Know You Seeds

Climate and Soil:

Watermelon is grown throughout tropics and subtropics. For seed production arid regions are preferred because of less disease incidence. Deep well drained sandy loam soils are good for watermelon with pH ranging from 6.5-7.0, but it can tolerate acidity up to pH 5.0.  

Isolation:

Water melon is a highly cross pollinated crop. Hence, the minimum recommended isoltion distance for foundation seed field is 1500m and certified seed field is 1000m.

Season:

North India : Jan-Feb

South India : Sept-Oct

Spacing: 200cm x 150 cm

Seed rate:

Female parent: 1 kg/ha.

Male parent : 250g/ha

Method of sowing:

The Male and female parents are grown in adjacent rows in the field in 1:3 or 1:4 ratio 

Shallow pit method: Shallow pits of 60 x 60x 45 cm size are dug at a distance of 200 x150 cm. The pits are left open for a week by filling 4-5 kg of FYM/compost by making circular basin. About 3-4 seed /hill at 2-3 cm deep are planted. 

Raised bed method: The seeds are sown on either side of raised beds.

Roguing:

Minimum of 4 roguings are done at following stages. 

Before flowering: Offtypes are identified and removed based on vegetative characters like foliage morphology, colour, vine growth etc. 

Flowering stage: Early and late varieties can be detected based on sex expression and sex ratio. 

Fruit development stage: Based on fruit characters 

Maturity stage: Based on flesh colour,rind thickness, seed color, TSS etc. Diseased plants are also removed as and when they are observed at all stages.

Fertilizers:

FYM- 15-20 tonnes /ha

N- 60-80 kg P- 40-60 kg K 60-8- kg/ha

Calbo (Calcium and borax mixture) is applied at 35-40 days after sowing or after first flower formation at 3-4g/l for better flower and fruit set.

Pollination:

Female flower buds in seed parent are covered a day before opening with butter paper covers. Male flower buds are removed as and when appear in seed parent. Male flower buds in pollen parent that are going to open the next day are tied with a thread such a way that the pollen remain within the flower even after anther burst. At the time of pollination the male flower buds are opened and exposed to sunlight for a while to make anthers to burst. Then, pollen is transferred on the stigmatic surface of the bagged female flower by holding the pedicel of the female flower. Care should be exercised not to touch the ovary of the female flower while pollination as it induces flower dropping. The best time for pollination is 7-9.00am for good seed set. A single male flower can pollinate 2-4 female flowers depending on the ability of male parent to produce pollen. Only one fruit is retained per vine and the maximum of 2 vines are retained per plant for seed production. Pruning vines should be done at 45 days after sowing.

Irrigation:

Irrigation should be given once in 5-6 days depending on soil type temperature etc. Frequent irrigation promotes excessive vegetative growth especially in heavy soils. Application of water should be restricted to the base of the plant or root zone to prevent diseases and rotting of fruits.

Diseases:

Powdery mildew: Karathane 0,2% or Bavistin 0.1%

Anthracnose: Bavistin seed treatment 2g/kg. Spray mancozeb 0.2%

Fussarium wilt: Seed treatment with Bavistin@ 2g/kg seed and drenching the soilwith Captan 0.2%

Water melon mosaic virus: Control of vector ie. Whitfly with metasystox @0.2%.

Water melon bud necrosis: Control of vector ie. Thrips by spraying Acephate@ 2g/l or Regent@ 1.5ml/l

Harvesting:

Normally the fruits mature after 60 days of pollination and the seeds turn from brown to black. Fully mature fruits can be confirmed when the tendrils have withered on the node bearing the fruit. There is a change in the colour of fruit part touching the ground from green to yellow and on thumping the metallic sound of rind changes into ruffled dull or dead sound.

Seed Extraction:

The flesh along with seeds is removed from the rind and macerated and kept for fermentation foe one day. The seeds, which settle down, will be separated from juice and flesh and washed thoroughly with water. Machines are also used for large-scale seed extraction.

Seed drying:

Soon after extraction seeds are first dried in shade by spreading on a mounted nylon net then under sunlight. Seed moisture should be brought down to 7% for open storage and to 6% for moisture proof storage.

Seed cleaning and grading:

Dry seeds are run through a air screen cleaner that separates large seeds from trash and small seeds. Seeds are graded based on their density by passing through specific gravity separator.

Yield: 225 –280 kg/ha.

Certification standards:

Field standards: 

Seed standards:

Author:

Dr.BS Tomar,

Sr. Scientist,

Seed Production Unit, Seed Science Division, IARI

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