It is about estimating the yield gap, which means (the actual yield of the given perennial crop in a specific location divided by the highest yield of the given perennial crop in that specific location under non-limiting conditions) in %.

Dear sir

In cashew, we used to express in terms of yield/tree, yield/hectare and cumulative yield/hectare.

But,  these two methods  ( Dr Amede and Dr Kalaivannan ) do not reveal the difference in fruit yield from tree-to-tree. Is there any method which takes into account the variation in fruit yield from one tree to another tree, while expressing the yield performance of perennials. 

Citrus trees in coastal Kenya have two distinct fruiting seasons per year. Fruit yield varies from tree-to-tree and from one season to the other. I find it rather impractical to base the performance of an orchard on its individual trees or on individual seasons. I suggest that orchard performance be expressed as fruits per unit area per year (e.g. fruits/hectare/year).

Thanks Dr Saha for adding another response.  You express orchard yield per unit area , let it ha , so I say orchard yield per ha . These expressions are more skewed towards average performance of trees in a given orchard. This again does not take into account the  variation yield from tree -to-tree. If we want to identify the different production zones in given orchard , and according those production zones , tailor the inputs ( In order to rationalise the input use ) use for better input-use-efficiency, such expression of fruit yield will never help us meet our objective.  

Can we include/consider tree biomass with individual tree yield...so that we can have a covariate analysis...harvest Index may be another option...???

How to express it mathematically Dr Prasad , I appreciate the suggestion .Harvest index , you will again calculate on the basis of average values again.

What about developing an index, some thing like Yield Performance / tree = YnoF*YwtF*EI; where by noF is number of fruits per tree, wtF is weight of fruits per tree and EI is the environmental index. EI could vary depending on the climatic and soil conditions. You may wish even to add a Quality index into the calculation.

Dr Tilahun , can you please refine it  further  so that it becomes more expressive . Then what kind of parameters , you will be adding as a part of quality index.

Thanks Dr. Srvastava for leading this interesting discussion. To add on my earlier message, YnoF will tell us the number of fruits per tree and YwtF combined weight will tell us the total output per tree. The EI could be expressed as aridity/wetness index, so that we are not comparing orange with apple. The quality index could be marketability or sugar content. The sum of all these should be able tell about the performance of the tree under a given environment.

Thanks Dr Tilahun again.  We can revise EI as an environmental index  , taking into account the premier climatic factors which have their impetus on the success or failure of crop . Likewise , the quality index needs to be developed on a very comprehensive  basis . for example , what quality parameters of a fruit ( For example citrus ) will decide the marketability . These could be ; size , compactness ,  peel color , presence or absence of neck , total soluble solids , acidity , juice content or some other parameters can be added and an index must come out on the basis of weighed means on a given scale. We can attempt the same for EI as well. It is so heartening to see , discussion moving into a forward direction .  

Great, it looks like a methodology is coming up; let us hear what other people think about it.

Yes , this is very important to listen to others  so that this issue finds a new headway  and a valuable addition to existing state of knowledge.

If we express the performance of perennial crops in terms of orchard efficiency  , whereby it takes into account the yield of every tree within a given field/orchard. We do not need an orchard where you have 50% trees having exceptionally high fruit yield and rest of the 50% trees exceptionally low fruit , and when you take the average , it becomes an orchard of optimum yield , giving highly misleading orchard performance .  

I never made such analysis, but every fruit-tree have to be a replication. The number of replications must be determined by usual statistical methods. The only care is that the  Anova is part of an analyse named repeated measures in space, because some fruit-tree are large and have strong influence of the sun position, or other weather conditions. In the magazine Horticulture Science has the theory behind the analysis.

The BMDP software has explanations and routines to run the analysis.

However, you can start with Exploratory Data Analysis to verify the best distribution to investigate such case. The VTFIT can help the probabilities and the Excel with the Action 2.6 can help in such cases. Except BMDP, all the others softwares are free for download.

I hope you enjoy the suggestions.

Walter

Excellent Walter . I was willing to see any such calculation for orchard efficiency , so that every tree  fruit yield is the  nearly the mean value of orchard in order to optimise the input-use-efficiency . Hope , you can provide further input . Since conventional style of expressing the orchard yield in form of mean orchard yield is very misleading . 

Excellent Walter . I was willing to see any such calculation for orchard efficiency , so that every tree  fruit yield is the  nearly the mean value of orchard in order to optimise the input-use-efficiency . Hope , you can provide further input . Since conventional style of expressing the orchard yield in form of mean orchard yield is very misleading . 

Is there any particular parameter/equation to determine the total yield under field conditions?

If I conducted a trail of chemical on 15 plants (replicate) how we can express in terms of per acre or hectare land?

And is it same for all the crop or it varies?

Please suggest any paper link or books for calculation

Thanks