PROBABILITY AS A BASIS FOR BARLEY CULTIVAR SELECTION BY GROWERS

Inadequate interpretation of cultivar (est results can lead to poor cu ltivar selection by growers and loss of farm income. Analysis of culti var mean yields does not allow comparison of predicted cultivar respon ses at different yield levels. Traditional tests of significance are i nappropriate for nonacademic clients of applied research. This study i ntroduces cumulative probabilities (CP) as an alternative method of ex pressing predicted cultivar response across the range of possible yiel ds. Cumulative probabilities, computed using the mean and standard dev iation of each cultivar in a normal probability density function, expr ess the probability growers have of obtaining or exceeding given yield s when planting each cultivar. Cumulative probabilities are compared w ith mean separation with LSDs for interpretation of results from 39 si ngle-replicate on-farm drill-strip tests of four spring barley (Hordeu m vulgare L.) cultivars conducted in 1990 and 1991 in Washington's mal ting barley zone. Providing growers with cultivar yield performance al one fails to provide an integrated basis for cultivar selection based on both yield and quality criteria upon which farm income is based. Te st weight, kernel plumpneSS, 2nd protein concentration for feed or mal ting premiums are integrated with grain yields to estimate net returns for each cultivar. In the farm production environment where the quali ty of cultivar selection by growers depends upon the quality of easily assimilated information, CPs of yields and expected net returns provi de informative criteria for cultivar selection.