Photosynthetic Heat Stability in Highbush Blueberries and the Possibility of Genetic Improvement

Abstract

Seven highbush blueberry (Vaccinium corymbosum L.) cultivars were evaluated for their photosynthetic heat stability. Ail showed significant reductions in CO 2 assimilation rates (A) as leaf temperatures were raised from 20 to 30C, although `Blue-crop', `Jersey', `Elliot', and `Rubel' (22% to - 27%) were significantly less affected than Spartan', `Bluejay', and `Patriot' (-41% to -51%). To determine whether temperature adaptations of highbush types can be broadened through hybridization with native, heat-tolerant species, `Bluecrop' was crossed with the V. darrowi Camp. selection Florida 4B, and F 2, BC 1, and BC 2, populations were generated. This approach showed promise as genotypes were identified in all the derivative populations that were more heat tolerant than `Bluecrop' and had a high A.