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Drought Resistance Index (DRI) Calculator

Calculate Stress Susceptibility Index (SSI), Mean Productivity (MP), and DRI for crop breeding and agronomy research.

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Category Statistics & Probability

Experimental Means (Global)

Genotype Data

GenotypeSSIMPDRI
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About

Plant breeders and agronomists need quantifiable metrics to select genotypes that perform well under water deficit. Relying solely on yield under stress is insufficient because it does not account for the genotype's potential under optimal conditions. This tool calculates three critical indices: SSI (Stress Susceptibility Index), MP (Mean Productivity), and DRI (Drought Resistance Index), allowing for a balanced ranking of crop varieties.

Lower SSI values indicate greater stress tolerance. High MP values indicate high average performance. A high DRI combines these to identify genotypes that maintain yield stability without sacrificing potential.

agronomy plant breeding statistics yield analysis genetics farming

Formulas

1. Stress Intensity (SI): Global measure of the experiment's severity.

SI = 1 − YsYp

Where Ys is the mean yield of all genotypes under stress, and Yp is the mean under potential (normal) conditions.

2. Stress Susceptibility Index (SSI):

SSI = 1 − (Ys / Yp)SI

3. Drought Resistance Index (DRI):

DRI = Ys × YpYp

Reference Data

IndexFormula SymbolInterpretation
Mean ProductivityMPAverage yield across stress and non-stress environments. Favors high yield potential.
Stress SusceptibilitySSIMeasures yield stability. SSI < 1 indicates better resistance than the experimental average.
Drought ResistanceDRIIdentifies genotypes with high yield and high stability. High values are preferred.

Frequently Asked Questions

An SSI > 1 indicates that the specific crop variety had a larger percentage yield reduction than the average of all varieties in the experiment. It is considered "Susceptible".
Some crops are very resistant (low SSI) simply because they have low yields even in good conditions. MP ensures you don't select a "survivalist" plant that produces no economic yield. You want high MP and low SSI.