An internal condition or stage of viable seed that prevents its germination although good growing temperature and moisture is provided. A state of dormancy is a resting state that must be broken by time, or special conditions, before a seed will germinate at temperature and moisture levels suitable for growth.

• Dry storage

For species where dormancy is naturally of short duration, it is often sufficient to store the

Sample in a dry place for a short period.

• Pre-chilling

The replicates for germination are placed in contact with the moist substratum and kept at a low temperature for an initial period, before they are removed to the temperature. Agricultural and vegetable seeds are kept at a temperature between 5⁰ C and 10⁰ C for an initial period of up to seven days. In some cases, it may be necessary to extend the pre-chilling period or to re-chill.

• Pre-heating

The replicates for germination should be heated at a temperature not exceeding 40⁰ C, with free air circulation, for a period of up to seven days before they are placed under the prescribed germination conditions.

• Light

The test should be illuminated during at least 8 hours in every 24 hours cycle and during the high temperature period when the seeds are germinated at alternating temperatures.

• Potassium nitrate

The germination substratum may be moistened with a 0.2 per cent solution of KNO₃ , prepared by dissolving 2 gm KNO₃ in one litre of water.

• Gibberellic Acid

The germination substratum may be moistened with 500-ppm solution of GA₃, prepared by dissolving 500 mg GA₃, in one litre of water. When the dormancy is weaker, 200 ppm may be enough. When it is stronger up to 1000-ppm solution may be used.

• Sealed polythene envelops

Where a high proportion of fresh ungerminated seeds are found at the end of the standard test retesting in a sealed polythene envelope of just sufficient size to hold the test satisfactorily will usually induce these seeds to germinate.

When germination is affected by a naturally occurring substance in the seeds, which acts as inhibitor it may be removed by washing the sees in running water at room temperature (25⁰C) before the germination test is made. After washing the seeds should be dried back at room temperature.

2. Removal of structures around the seed

Germination of certain spp. is promoted by removing outer structures such as involucre of bristles or lemma and palea of certain Gramineae.

A fungicide treatment may be applied before planting the seed for germination, when the seed lot is known not to have received such a treatment.

1. Soaking

Seeds with hard seed coats may germinate more readily after soaking for 24-48 hours in water. The germination test is commenced immediately after soaking.

2. Mechanical scarification

Careful piercing, chipping, filling or sand papering of the seed coat may be sufficient to break the dormancy condition. Care must be taken to scarify the seed coat at a suitable part in order to avoid damaging the embryo and the resulting seedling.

The seeds are soaked in the acid until the seed coat becomes pitted.

Ag.
Technologies
(Seeds)