Dear Shiv,

If you had mentioned the species or genus, a more detailed answer could have been given. Also, if you had mentioned what the main objective of the study – for example, are you interested in identifying the age of seed lots or want to compare variety differences using seeds of same age? In general, I would say the dry matter is a better measure than height because the height can be affected by density of sowing, light intensity etc. If you are interested in doing a detailed study, biochemical parameters also need to be taken into account. Glutamic acid decarboxylate seems to correlate well with seedling vigor in cereals (grasses) whereas tetrazoilium test, glucose levels in imbibed seed and respiration seem to be useful parameters in legumes.

Ranjith

in general terms, measuring seedling vigor via dry matter accumulation is better assessment than seedling  elongation  which may be subject to change due to population density, spacing, shade. Again it depends on whether you want destructive sampling or not.

Dear Justin

Thanks for writing your view. Actually I am estimating Brassica seed vigour in lab following Abul Baki and Aderson formula (SVI-I= Seedling length X Germination and SVI-II= Seedling Dry Wt. X Germination). Here, question relates to my inquisitiveness  that why we should go for two calculation? Can we not do away with only one? If one, which should we use and why? If it is case to case/situation to situation than what should be our scientific considerations?

Regards

SHIV   

The assumption in Vigor index II is that it measures the dry matter accumulation rate of the normal seedlings. Seeds with better level of reserve macro-molecules are assumed to have better rate of dry matter accumulation, so far as there is no dormancy problem. SVI-II, therefore, is an indicative of the seed food reserve, which is very important in seed vigor. 

I suggest second method (SVI-II= Seedling Dry Wt. X Germination) for agriculture species, if there is no issue of destructive sampling.  

Dear Shiv,

If you do not have an information specific for the species you are studying, I suggest you perform a correlation study with standard germination test, SVI-I , SVI-II, emergence in field or in nursery trays and field seedling vigour and other vigor tests.

When I don´t have information about what vigour test to use I do this.

Hope it helps you.

Barbara

Dear Dr Shiv Yadav ,

Thank you for your question. for seedling traits, the measuring of length, weight fresh and dry, CGR and RGR

with bets regards

Khaled

Thanks Dr. Khaled for your kind input.

Yes seed vigour index II is best option of measuring the viour of the seed. In case of ber, gibberellic acid @ 250 ppm for 24 hours resulted into higher vigour index. Thanks

(a) First count: The test is done along with the regular germination test. The number of normal seedlings, germinated on the first count day, as specified in the germination test for each species, are counted. The number of normal seedlings gives an idea of the level of seed vigour in the sampIc. Higher the number of normal seedlings greater is the seed vigour.

(b) Seedling growth rate and dry weight: The seedlings arc grown either in laboratory, green house or field. In laboratory, in between rolled towel paper method should be followed. Tenseeds are planted in the centre of the moisttowel papers in such away that the micropylesare oriented towards bottom toavoidroot twisting. The rolled towel papers are kept. in the germinator maintained at a temperature recommended for crop in reference. After a specified period of time (5-10 days) towel papers are removed and five seedlings are selected, their length is measured and mean seedling length is calculated. Seed lots producingthe taller seedlings are considered more vigorous than the seed lots producing shorter seedlings. For dryweight determination, the seed lings are removed and dried in an air oven at 100°C temperature for 24 hours. The seedling dry weight provides additional information for assessing seed vigour.

(SVI-I = Seedling length X Germination & SVI-II = Seedling Dry Wt. X Germination)

I think both, the seedling length and dry matter are important from vigour point of view. In the field, the seedlings which are longer in initial stage may maintain their height throughout, besides the varietal characteristics. And may also attain their destined height early. And afterwards, will give more time and nutrients to seed development and maturity.

And the heavy seedlings (more dry weight) may give well established plants from initial stages. They would be more strong towards the biotic and abiotic stresses imposed on them.

According to Abul Baki and Aderson the formula of Vigour Index –I and Vigour Index –II:

Vigour Index –I = Seedling length (cm) X Germination%

Vigour Index –I I= Seedling Dry Wt. (g) X Germination%

Generally, most of the laboratories follow Vigour Index –I formula.

But, Vigour Index II is best option of measuring the vigour of the seed as it measures the dry matter accumulation rate of the normal seedlings.

SVI -II is better index as it gives good correlation with field emergence of seed lots

x I=Seedling length (cm) X Germination% + Vigour index II = Seedling dry wt (g)