Viability Test

SEED VIABILITY:

Seed viability is defined as the capacity of the seed to remain capable of germination for some specific period of time 

1) Respiration Test : Respiration.  is an indication of life but such tests are complicated

2) Electrical conductance method:

Seeds are soaked in distilled water and electrical conductance of such water is tested 

The increase in conductance is roughly proportional to the percentage of dead tissues

3) Potassium Permaganate method:

It  is a qualitative test to find out whether seeds are viable 

4) Indigocarmine method:

Portion of dead seeds is determined by counting the number of stained

5) Embryo Culture Method:

Takes about 7-10 days , judged by counting the number of germinated embryos

6) Tetrazolium Chloride Test :

Known as biological test. Seeds are soaked in 0.5 - 2% solution of 2,3,5 

triphenyl Tetrazolium Chloride. Using vacuum and maintaining a temperature of 40-45°C , it takes only 4-5 minutes to complete a test of 100 kernels

7) Grodex Test:

Grodex is a seed germination indicator and is a brand name of triphenyl Tetrazolium bromide in powder form

SEED MOISTURE:

Germination occurs when seed moisture is above 40-60%

The moisture determination in seeds by- 

1) Traditional bite test 

2) Electrical moisture meters 

3) Infra-red moisture meters 

4) Oil distillation method

5) The lab.oven method

6) Karl Fisher reagent method

SEED DORMANCY:

Dormancy is the arrested development and reversible rest period of plant organs either of a seed or of any vegetative part .

Dormancy can be broken artificially by various special treatments which may be grouped into two groups

A) PHYSICAL TREATMENT:

1) Heat treatment at 40-45°C fir different duration

2) Low temp.treatment at 2-8°C for 12-24 hours but seeds should be presoaked for 36 hours before they are given the low temperature treatment

3) Alternate heating and cooling for several times

4) Alternate drying and wetting for several times

5) Exposure for 24 hours of water soaked seeds to red light for 1-2 hrs. at 15-25 °C temp

6) Dehusking or removal of seed coats (Scarification) by rubbing to make it permeable to water

CHEMICALS:

a)  Inorganic Chemicals:

1) by acid treatment:

Dilute solutions of HNO3  or H2SO4 (0.1-0.5%) for different durations in minutes

2) KNO3 (1-3%)

Strongest and used for immediate dormancy break after harvesting 

3) by gases: by increasing O2 concentration

b) Inorganic chemicals

1) Non hormonal: Thiourea , Ascorbic acid 

2) Hormonal - GA3 (1-1000ppm) Commonly used hormone to break dormancy 

Ethylene (Ethrel solution of 100-300 ppm)

DEHUMIDIFICATION: Removal of water vapour from the air in storage 

*Silica gel is the most common desiccant used as chemical dehumidifier

TEMPERING- Process of bringing or other products to a desired moisture or temperature for processing

*Indian seeds act passed in 1966

✍️ Agricos

Vaishnavi Nimkar 🌾🌱