Pecan Nut and Kernel Characteristics Show Genotype–Environment Interactions

Abstract

Abstract Results are presented for performance of pecan [Carya illinoinensis (Wangenh.) C. Koch] clones at six established National Pecan Advanced Clone Testing System (NPACTS) sites for 16 nut quality factors from 1980 through 1985. Total nut weight and percent kernel were significantly greater at Tulare, Calif. than at any other location, with ≈80% of the clones averaging 6.5 g/nut or more and ≈90% averaging at least 54.5% kernel. Nut weight was smallest at El Paso, Texas. Daily mean temperatures during nut expansion may be a major factor determining nut weight response. Low nut density was characteristic of more clones at Baton Rouge, La. than at any other location. Kernel color was lightest at El Paso and darkest at Baton Rouge, with darker color appearing to be related to high field moisture conditions before harvest. Nut weight was not related to kernel percentage, color, or percent kernel covered with fuzz (packing material); thus, large nuts are not necessarily of lower quality and can be selected in an effective breeding program. Amount of nut “packing material” retained in the sutures of kernel halves after shelling was generally not related to other traits, except that material retained in ventral grooves increased with nut and kernel weight. Depth and width of dorsal grooves were not related to retention of packing material and can be disregarded in future pecan nut evaluation systems. Many other expected character relationships were verified and the overall NPACTS nut evaluation system will be revised based on these results.