Environmental, physiological and genetic mechanisms contributing to clonal differences within the cultivars Norgold Russet and Russet Norkotah

Abstract

Studies were conducted in the field at Springlake, Texas and in the growth chamber at College Station, Texas to investigate the environmental, physiological and genetic mechanisms contributing to clonal differences in the potato (Solanum tuberosum L.) cultivars 'Norgold Russet' and 'Russet Norkotah'. The morphological characterization was performed at different stages of tuber bulking (1/3 = 60 [plus or minus] 5 DAP, 2/3 = 105 [plus or minus] 5 DAP, and 3/3 at final harvest) at both locations. Significant differences were found between and within cultivars for most of the morphological and horticultural parameters studied in both locations. Subclones better adapted to the growing conditions normally found in Texas have stronger vines, are later maturing and have a higher marketable yield. Photosynthetic assessments also confirmed differences among clones of the same cultivar. Isozyme analysis using polyacrylamide gel electrophoresis was performed on leaf and tuber samples harvested at the tuber bulking stages described earlier. Eighteen isozyme systems were studied initially, seven of which provided reliable intracultivar and intercultivar variation in band expression. Banding patterns, although stable within a tuber bulking stage, were variable between harvest dates in both locations during both years of the study. Developmental and environmental influences on banding polymorphism were corroborated in genotype by environment interaction studies carried out separately. RAPD analysis using arbitrary and specific primers provided different DNA amplification products that could be the result of genetic differences within cultivars.