TESTING PHILOSOPHY BREEDER VS. OVT

NULL HYPOTHESIS BREEDER- THERE ARE DIFFERENCES OVT – THERE ARE NO DIFFERENCES

ALPHA LEVEL BREEDER – NONE NEEDED OVT – Carmer 1976 Crop Sci. 16:95-99. .20 -.40

CHARACTERISTICS OF TEST SITES BREEDER – HIGH DISCRIMINATION OVT – REPRESENTATIVE OF GROWING REGION

DISCRIMINATION REGRESS ENTRY MEANS BY LOCATION ON ENTRY MEANS ACROSS LOCATIONS, Ref. Brown, Sorrels, Coffman. Higher ‘b’ values indicate better discrimination

REPRESENTATIVE OVTs CONDUCTED UNDER OPTIMUM, AVERAGE, AND BELOW-AVERAGE CONDITIONS TO REPRESENT AVERAGE GROWER’S CONDITIONS… Salmon, 1951

NUMBER OF TRIALS BREEDER HAS LIMITED SEED SO NEEDS A FEW DISCRIMINATING SITES OVT PROGRAM NEEDS TO SAMPLE ENVIRONMENTS

HOW MANY SITES ARE USED BY OVT PROGRAMS ?

Average and median number of sites BARLEY -5 CORN – 13 COTTON – 7 SOYBEAN -10 WHEAT - 9 MEDIAN BARLEY – 4 CORN – 9 COTTON – 6 SOYBEAN – 8 WHEAT - 7

RANGE OF ACRES PER TEST SITE BARLEY – 10,000 TO 30,000 CORN – 31,000 TO 417,000 COTTON – 33,000 TO 294,000 SOYBEAN – 75,000 TO 680,000 WHEAT – 28,000 TO 457,000

HOW MANY TEST SITES ARE ACTUALLY NEEDED?

Vmean =

WHAT IS AN ACCEPTABLE LEVEL OF PRECISION? LSD = 10% OF THE MEAN SEEMS REASONABLE TO ME !

CORN EXAMPLE AVERAGE YIELD OF 140 BU/A LSD = 14 BU/A NEED S.E. OF MEAN DIFFERENCE= 7.0 USING 2 YEARS, 5 REPS THEN LOCATIONS NEEDED WOULD BE 4 AVERAGE NUMBER OF TESTS LOST = 1.5 SO I NEED 6 TESTS TO COVER 750,000 a

POINTS NULL HYPOTHESIS – DIFF. VS. NO DIFF. ALPHA LEVEL – NONE VS. 0.2 SITES – DISCRIMINATORY VS SAMPLE SITE NUMBERS – FEW DISCRIM. VS DESIRED LEVEL OF PRECISION