Factors affecting head formation of iceberg lettuce (Lactuca sativa L.).

Abstract

In a series of greenhouse experiments (winter and spring, 1980-85), significant differences in frequency of (undesirable) open head formation were detected among 6 cultivars. Starlina, Aubade, Cristallo and Kellys showed 18-38% open heads, whereas Sonia and Marbello had <10%. Head weight of Starlina was lower than that of the other cultivars, which did not differ in yield. In experiments with Cristallo, maintaining root temperature above 14 degrees C throughout the growing period resulted in a low percentage of open heads, while application of a fixed thermal screen resulted in better head formation but lower head weights than in controls. (Abstract retrieved from CAB Abstracts by CABI’s permission)