EXAMPLE SAS PROGRAM #3 FOR ESTIMATING HERITABILITY AND ITS STANDARD ERROR


Example SAS codes correspond to J.B. Holland, W.E. Nyquist, and C.T. Cervantes-Martinez, "Estimating and Interpreting Heritability in Plant Breeding: An Update," submitted to Plant Breeding Reviews.  Manuscript available on request: james_holland@ncsu.edu.

Heritability based on regression of F2:3 progeny means on individual F2 parents and based on variance among F2:3 families evaluated in an unbalanced, multi-environment trial.

Data are taken from Holland et al. (1998) Theor. Appl. Genet. 96:232-241.

Briefly: southern rust scores were made on 140 individual F2 (S0) plants in Florida, 1991.  Plants were also self-pollinated.

Self-pollinated progeny of each individual F2 (F2:3 or S0:1 families) were grown in replicated trials in North Carolina, 1991. Scores were made on the basis of mean progeny response to southern rust disease.

Selected F2:3 families were also grown in replicated trials in North Carolina, 1994.

Holland et al. (1998) estimated heritability on the basis of (1) offspring-parent regression using 1991 NC means on 1991 FL scores, (2) a second estimate based on variance components estimated from replicated evaluation of F2:3 families in 1991 NC, and (3) an estimate of "repeatability" on the basis of variance among selected (not random!) F2:3 families in 1991 and 1994 NC.  

SAS code is given below to improve the efficiency of heritability estimation.  First, offspring-parent regression is augmented by inclusion of information from NC 1994 environment on offspring.  Second, heritability estimate based on F2:3 families is augmented by inclusion of NC 1994 data.  This eliminates the need for the estimate of "repeatability" from selected F2:3 lines, and also eliminates bias due to GE interaction variance that was present in the original estimate of heritability on the basis of F2:3 family data from a single environment (1991 NC).

To perform the analysis you need to download the following two files:

Original data on a single plant basis for F2s or on a plot basis for F2:3 families is available in an Excel spreadsheet file .  To use the SAS code given, this spreadsheet must be open when running the SAS program!

SAS code for conducting heritability estimation analyses.

You can compare your results to mine, found in the output file .

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