In fruit tree nurseries, most of the fruit species are propagated through vegetative methods but some fruits like Jamun and phalsa are still propagated by seeds. Besides this, the seed is also the main source for raising rootstock on which the plants are budded or grafted.

Seed extraction

The rootstock has a profound effect on the vigour, precocity, fruit yield and quality and longevity of scion, so proper care should be taken in the selection of seed source. An ideal rootstock should have the following characteristics:-

1. Easy to propagate by seeds or by cuttings.
2. The high degree of polyembryony in some fruits like citrus, mango, etc.
3. Compatible with scion cultivar.
4. Dwarf, precocious with high yielding impact on the scion.
5. Vigorous in early age with well-anchored roots and free from suckering.
6. Adaptable to problematic soils (moist, drought, saline, calcareous, etc.)
7. Adaptable to unfavourable weather conditions.
8. Resistant to pests and diseases.

The seed should always be extracted from fully ripened fruits collected from healthy, vigorous, and high-yielding trees.

Handling of seeds

After extraction, the seeds should be washed properly with water and dried in shade. The seeds of sub-tropical fruits should preferably be sown immediately after drying.

Seeds can also be stored in cool and dry places in air-tight containers for a certain duration as given in Table 1.

Table 1. The storage longevity of fruit seeds

Fruit	Longevity (Years)	Fruit	Longevity (Years)
Almond	5	Apricot	5
Apple	2-3	Cherry	1-3
Citrus	Immediate sowing is best	Mango	30 days
Peach	5	Pear	3
Pecan	1-3	Plum	4-6
Walnut	1-3

 

Pre-sowing treatment

1. Scarification

The seeds which are having very hard seed coat require scarification prior to sowing which can be done by breaking, scratching, altering, or softening the seed coverings.

• The seeds of ber, peach, and walnut can be scarified by cracking of seeds with the hammer.
• The scarification can also be done by giving hot water treatment (77⁰-100⁰C) for few seconds followed by cold water treatment for 12-24 hours.
• The scarification of guava seed can also be done by giving 0.25% HNO₃ treatment for 3 minutes.
• The use of concentrated H₂SO₄ for 5-10 minutes and 500 ppm GA₃ overnight as a seed treatment is very useful to enhance the seed germination of ber and Aonla, respectively. The seed should be thoroughly washed after acid treatment.

2. Stratification

Prior to sowing, seeds of temperate fruits need some period of rest under moist chilling conditions for germination as given in Table 2.

Table 2.  Duration of seed stratification (at 1-5⁰C) in moist sand medium

Fruit	Stratification duration	Fruit	Stratification duration
Apple	50-70 days	Almond	45-50 days
Pear	40-50 days (30-35 days for P.pashia)	Walnut	95-120 days
Peach	60-70 days	Pecan	70-75 days
Plum	60-70 days	Persimmon	90-100 days
Apricot	45-50 days

 When controlled temperature conditions for stratification are not available, sowing of seed is done directly in the nursery in the month of November-December in cool areas.

3. Chemical

The seed germination can be improved by treating the seeds with 5000 ppm thiourea for 15-20 hrs (peach and grapes), 100 to 500 ppm GA₃ for 12 hrs (for apple, cherry, peach, and hazelnut), 5000 ppm ethrel (for guava) and 10-20 ppm benzyl adenine (for apple).

 

Preparation of seedbed / container

• The growing media to be used must be sufficiently firm to provide anchorage to seeds or cuttings, well-decomposed with a high C:N ratio, free from weeds and harmful pathogens, cheaper and readily available, and should have slightly acidic pH and good water holding capacity with sufficient porosity to drain excess water.
• For raising seedlings, the bed of 2-3 m (L)  x 60-100 cm (W) x 15-20 cm (H) should be prepared by mixing 2 parts loamy soil + 3 parts leaf mould + 5 parts sand.
• This soil media must be sterilized either by covering it with a white plastic polyethylene sheet for 4-6 weeks during the hottest part of the year or with 2% formalin solution / basamid fungicide (300 g / cubic meter of media).
• This media should be mixed with 2.5 kg of base fertilizer mixture of (1.8 kg CAN or Ammonium sulphate + 2.5 kg Super phosphate + 1.0 kg Muriate of potash) per cubic meter of root media.
• This media with the base fertilizer can also be filled in containers, earthen pots, polyethylene bags, etc. for raising seedlings.
• The seeds of deep-rooted fruits (ber, jackfruit, walnut, etc.) can be sown directly in the pit called in situ

Seed sowing

• The seeds of sub-tropical fruits should be sown immediately after extraction from the fruit, while the seeds of temperate fruits should be sown after their stratification.
• Since citrus seeds are available in the winter months, the protection with alkathene tent is essential for increasing germination and the proper growth of seedlings.
• The seeds should be sown at a proper distance and the depth of the seeding is kept 3 times the thickness of the seed. The seeding distance of some fruit species is given in Table 3.

                           Table 3. Seeding distance of some fruit crops

Fruit	Distance	Fruit	Distance
Citrus and guava	10 cm x 2 cm	Apple, pear, peach, plum	30 cm x 10-15 cm
Mango	45 cm x 15-20 cm	Phalsa	10-15 cm x 15 cm
Jamun	25-30 cm x 15 cm	Ber	30 cm x 15 cm

                                                 

• The germination period of seeds varies with the crop and is given in Table 4.

Table 4. Seed germination period after sowing

Fruit	Germination period (in days)	Fruit	Germination period (in days)
Apple	75-100*	Ber	40-50
Apricot	20-25*	Mango	25-30
Citrus	21	Peach	45*
Guava	25-30	Pear	45*
Plum	30*	Cherry	20*
Walnut	30*	* After stratification

Aftercare of seedlings

• After sowing, the bed should be covered with a thin layer of pulverized soil or some other materials like wood ash plus well rotten farmyard manure.
• If there is a need for irrigation, water should be given with a very fine nozzle. The frequency of irrigation in seedbeds depends upon the weather and soil conditions.
• Hand weeding should be done to check the population of weeds.
• The nursery bed should be protected from the summer heat by thatching with paddy straw and sugarcane leaves, sowing of arhar around the bed, irrigation, etc., and winter killings by thatching, irrigation, smoking, polyethylene tents, etc.
• In areas, where rapid death and collapse of seedlings occur in nursery, the drenching of nursery beds with carbendazim  (100 g) + mancozeb (250 g) per 100 ml of water should be done.

Transplanting

After attaining the age of transplanting (Table 5), the seedlings should be transplanted in properly leveled and well-irrigated and drained beds which have been liberally supplied with well rotten FYM/organic manures.

The seedlings should be planted in twin rows at 30 cm x 15 cm distance. The distance between twin rows should be kept 50-60 cm for performing other nursery operations.

Table 5. Transplanting age of seedlings

 Fruit                                                  Age

Mango                                                  2-3 weeks

Jackfruit                                               1-2 years

Bael                                                     1 year

Ber                                                       2 months

Phalsa                                                  8-10 months

Jamun                                                  10 months

Citrus                                                   4-5 months

Guava                                                  4 months

Loquat                                                 4-5 months

Temperate fruits                                 8-10 months

Proper care (irrigation, weeding, nutrition, plant protection measures, etc.) of these seedlings should be taken in the transplanting beds.