For grain crops such as peas, harvest index (HI) is the ratio of harvested grain to total shoot dry matter, and this can be used as a measure of reproductive efficiency.

Ratio is a number representing a comparison between two things while percentage is the amount, number or rate of something, regarded as part of a total of 100. But they are really analogous. For example: What ratio is the following: 50%? It is half because 50 is half of 100.

I hope this helps!

The ratio allows to extract surface yields that can be treated indipendently but percentage or HI are an easy way of giving efficiency, both affected by statistical bias in analysis of variance. for example a parcel gave 160 kg of total harvest and 40 kg of peas that is an HI of 40/160 or 0.25 or 25%, but whereas 40 or 160 can be treated as normal variables their relative ratio requires a correction for binomial distribution in any comparison. http://statisticalconcepts.blogspot.it/2010/02/transformation-of-data-validity-of.html

Good points Andrew, yes harvest index (HI) is the ratio of harvested grain to total shoot dry matter, and this can be used as a measure of reproductive efficiency.

Dear Nannim,

Other colleagues have already explained the term ''Harvest Index''. On the second part of your question, I wish to inform you that in literature Harvest Index (HI) is expressed in both ratio and percentage.

For example: if your harvested grain yield is 400 kg and total dry-matter yield (grain plus straw) is 1000 kg, then HI is 400/1000= 0.40, which is equal to (400/1000)x100%=40%.

Hope the information is useful to you.

The above colleagues have made good submissions that fully explain the subject matter. In addition it can be emphasize that  in calculating HI  the numerator / value should represent the economic portion while divisor should comprise all other biomass including  the economic  components