HERITABILITY AND PHENOTYPIC CORRELATIONS OF 6 PECAN NUT CHARACTERISTICS

Heritability estimates for pecan [Carya illinoinensis (Wangenh.) K. Ko ch] nut weight, nut buoyancy, nut volume, nut density, kernel weight, and percentage kernel were determined from 8748 nut samples representi ng 152 families collected during 25 years in the U.S. Dept. of Agricul ture (USDA) pecan breeding program at Brownwood, Texas. Measurements w ere corrected for year-to-year environmental variability using least-s quares constants of individual year effects. Adjusted values were then regressed on midparent means. Generally, heritability (h2) estimates were low to moderate: nut weight 0.35, nut buoyancy 0.18, nut volume 0 .35, nut density 0.03, kernel weight 0.38, and percentage kernel 0.32. The low values are probably due to the extreme alternate bearing tend ency of this species, since crop load affects pecan nut characteristic s so directly. Phenotypic correlations among these traits showed that larger or heavier nuts had significantly higher kernel weight, buoyanc y, and percentage kernel. Nut density increased with higher nut and ke rnel weight, but decreased with nut volume.