Infact it is root biomass and root configuration which translates into higher crop yield via improved nutrient and water uptake plus improving in rhizosphere biology as geobiochemical cycling....

Anoop Kumar Srivastava Sir, true that roots do contribute. But, is there something called root efficiency where without much change in the morphological parameters the roots can work better under demanding situations? We have not seen any significant correlation of the root:shoot ratio with yield in cotton. But these are just preliminary experiments. Maybe, as the crop growth progresses there would be a lot of buffering within the plant system of which the root is a major component. If there are conclusive studies in any other crops starting from seed to maturity, I think it will show us the way in cotton. The difficulty with cotton is its very long duration and a deep root system making it very difficult for rhizotron studies.

You can easily partition the accumulation of nutrients in various types of roots vis-a- vis shoots to arrive at such conclusion...

@ Rajesh, Plants receive water and nutrients mainly through roots beside foliage. So, the main contribution towards yield is by plant roots. The attached file may provide you some details information.

I would add to this interesting discussion that it is challenging to determine the contribution of roots to crop yield because in agriculture we rely primarily on annual plants. Their cycle is too short to determine a reliable contribution by roots. However the study of perennial plants like the herbaceous species that grow on prairie/grasslands show that roots grow 2-3 times more that what grows above ground. In its growth and exploration underground root growth contributes to building the SOM, which feeds the soil bacteria, contributing to the health of the plant and its yield/productivity. For this reason I support the idea of shifting agriculture toward a cultivation of perennial plant species.

J. C. Tarafdar , Thanks sir for the paper. Right now we do not have proper pointers in cotton as it is a deep rooted long duration crop. Moreover, it is drought tolerant inherently making it an interesting but difficult case study for root dynamics. But we do have irrigated and rainfed genotypes and their niches are specific. Maybe, we need to look at this and create populations for root studies. Right now, we are not looking at the below soil part and maybe a bit of effort there may help us in increasing yields especially under drought.

Bruno Borsari , Thanks for another perspective ! But have we not moved from perenniality to annuality in at least, the food crops? There may be no going back as long as our population keeps growing which needs the "assembly line" kind of agricultural production. But again YES, to the perennial plants with a definable plant type. If cost of cultivation is factored in, then perennial plants are the answer. Interesting line of research which may certainly suit some crops.

Dear Dr. Patil,

You may be interested to the work of The Land Institute in Salina, Kansas where they have been working/developing without any biotechnology a few perennial varieties of common cultivated crops, like wheat and sunflower.

https://landinstitute.org/our-work/perennial-crops/

Thanks Dr. Bruno for the link. Will follow it up.

In some literature it is reported that root dry weight is normally associated with crop yield than root length.....

The root of plants in the context of medicinal plants have very much significance in terms of economy. Because in some plants only roots have medicinal value.

Nazir A. Pala ,, Thanks sir. All the more reason that breeding for roots in some crops is more important.

Contribution of root in annual and perinal is highly significant, quantification of root contribution in perinal crop is easy as compared to annual crop but in annual crop root also supported the growth of above ground part. In case of medicinal plants root is more useful for contributing the secondary metabolites.

Roots are the backbone of the crop itself. Roots are the gateway for nutrient and water uptake which are virtually critical to crop yield. They are important component of the rizosphere where mutual interactions between the plant and microorganisms can directly influence crop yield. They play huge roles specifically in legumes, root vegetables, and medicinal plants.

Mohammed A. Mohammed , Thanks for your inputs. We are trying to discuss the root system's efficiency while fully knowing they are important.

Roots play a vital for plant economic yield, it’s main part of the plant to absorb of water and inorganic nutrients.

The roots of a plant have several important functions. The roots anchor the plant in place, resisting the forces of wind and running water or mud flow. The root system takes in oxygen, water and nutrients from the soil, to move them up through the plant to the stems, leaves and blooms.  Roots often store the energies created by the plant through photosynthesis, to make them available to the plant as it is needed. Plant roots also stimulate and support microorganisms in the soil that benefit plant life. All these factors contributes to a plant's economic yield.

Thans Hafiz Ghulam Muhu-Din Ahmed , can you expand your answer to root efficiency etc. in the light of breeding-underground traits !!!

Main function of root is to absorb water and nutrients. So root helps in economic yield.

Thanks ABDUL Aziz , what about root dynamics and their efficiency?

Qunatification of contribbution roots in crop economic yield is simply not possible , but without an iota of doubt , it is the health of roots and their configuation that dictate the magnitude of crop response...... and off course, the economic yield

Anoop Kumar Srivastava , True Sir, but correlation and path analysis do give us an idea. I am trying to focus on root efficiency wherein with a limited mass of roots can a plant still do better under drought? Root efficiency , basically. Sometimes, hard soil does not allow better root growth. The difficulties of the root are too many and we may not have had a clear understanding of what happens below ground. Maybe, we can still sustain yields under tough conditions with better root preparedness.

These are known facts , unless you redefine root configuration with regard to a crop. Root efticiency , which part of active zone, are you concerned . In that context , nondestructive measurement of roots architect is very important