A tool to predict fruiting in terms of number of days after anthesis based on fruit skin and pulp colour of pitaya (Stenocereus thurberi (Engelm.) Buxb.).

Abstract: A model for the prediction of fruit development stage in Stenocereus thurberi [Lemaireocereus thurberi] was developed. Fruits were sampled from a field in Hermosillo, Sonora, Mexico, in June and July 1999 and 2000, at 5, 10, 15, 20, 25, 30, 37 and 40 days after anthesis (DAA). A Minolta chromameter CR-300 set was used to quantify fruit skin and pulp colour. A multiple linear model was developed using the stepwise procedure in forward selection. F statistics, mean square error, coefficient of determination, Mallows coefficient, and distribution of residuals around zero were used as indicators of the efficiency of model prediction. The results indicated the possibility of predicting the fruiting stage in S. thurberi in terms of DAA based on fruit pulp and skin characters.