Introduction to the problem

Crop by region

Sorghum Asia Hybrid Seed Parent Program

Problem specification

The number of parents, crosses and progeny per cross in seed parent program

Breeding strategy component tackled

Crossing

Breeders’ equation terms tackled

\(\sigma\), i

Hypothesis

Finding the optimal number of parents, crosses and progeny will maximize rate of gain per dollar invested

Asia Sorghum Seed Parent Pipeline

Materials and methods

Treatments

Treatment Description
50-50-300 Current scheme, using 50-60 new parents in the crossing block making about 50 crosses and generating 300 progeny per cross
GRID A grid of #of parents (25-75), crosses (40-60), progeny per cross (200-400) constraining from 14,000 to 20,000 generated individuals entering the SSD pipeline

 

Simulation procedure

  • A 20 year burn-in period was modeled using the current breeding scheme. The burn-in was followed by a 50 year evaluation period to measure rates of genetic gain for all treatments

  • Genetic gain was measured by assessing changes in genetic merit in the F2 and F7 population

  • All evaluations were conducted using 15 replications

  • We simulated 1 complex to be behind the genetic merit and inferred through a selection index with 0.5 dominance effect

Results

Results - All Scenarios at Year=70

Results - F2 Population

Best 5 Scenarios at F2

Relative effect of parents at F2

Effect of cross & progeny in F2

Optimal cross & progeny at P=45

Optimal cross & nInd at P=45

Results - F7 Population

Best 5 Scenarios at F7

Relative effect of parents at F7

Effect of cross & progeny n F7

Optimal cross & progeny at P=25

Optimal cross & nInd at P=25

Conclusion

  • At F2 population, by year 70, the best crossing strategy (45-50-400) produces 3.01% increase in gain than current practice (50-50-300)

  • At F7 population, by year 70, the best crossing strategy (25-60-300) produces 12.83% increase in gain than current practice (50-50-300)

Based on F7, we recommend reducing slightly the number of parents (i.e. 25), and using a convenient #of crosses and progeny (i.e. 25-60-300) to maximize the genetic gain in the medium term (~50 years) given the current selection scheme