Relationship between kernel size features and test weight in Triticum durum

Test weight or bulk density in durum wheat is a physical quality characteri stic considered by semolina millers. High test weight values are desirable because they positively influence market grade and price. This study report s data on kernel size features, determined on a sample size of only 25 kern els, replicated three-times, of 16 commercial durum wheat cultivars grown i n two locations in southern Italy, to ascertain whether some kernel traits could be related to test weight. For each year and cultivar, the analysis o f variance for all of characteristics showed that sample size effect was no t significant, enabling the use such a small sample for further investigati ons. The kernel trait with the highest variation for year was kernel width. The absolute variation of 1994 with respect to 1993 growing season was 30. 9%. While kernel weight or volume did not correlate with test weight, a neg ative association with kernel length (r = -0.61, P = 0.05) and perimeter (r = -0.57, P = 0.05) was found. The kernel shape factors, rectangular aspect ratio (RAR) and circularity shape factor (CSF), showed a positive correlat ion with test weight (r = 0.51, P = 0.05 and r = 0.59, P = 0.05, respective ly). The shape factors were negatively correlated both with kernel length a nd perimeter and positively with kernel width. A predictive model for test weight (TW = 38.7 +/- 5.1.ETW, where the estimated test weight [ETW] was co mputed as individual. kernel weight/estimated kernel volume [EKV] ratio), w as highly correlated with actual test weight values (r = 0.82, P = 0.001). The effectiveness of the linear model was confirmed when a set of 10 advanc ed lines of durum wheat were considered, although a slightly lower correlat ion (r = 0.73, P = 0.05) between actual and predicted test weight values wa s found. Because the extent of predictability of this approach might be mor e effective in early-generation lines, the application of the findings in a durum wheat breeding program would be advisable.