Inheritance of bolting tendency in lettuce Lactuca sativa L.

Resistance to early flowering is an important attribute of lettuce cultivars adapted to tropical conditions. Lettuce cultivars may vary widely in the number of days necessary from sowing to inflorescence formation and flowering. In this paper, we report on the polygenic inheritance of the number of days to flowering in two crosses among contrasting lettuce cultivars – Vitória × Brasil-303 and Babá × Elisa. F₁ and F₂ seed were obtained for each cross, and used to estimate broad sense heritabilities. F₃ families were obtained from randonly sampled F₂ plants, and used to estimate narrow sense heritabilities based on parent-offspring regression. Trials were carried out in plastic greenhouses in Campos dos Goytacazes, in the Northern part of the State of Rio de Janeiro, Brazil. Broad and narrow sense heritabilities for days to first anthesis were 0.737 and 0.489 for the cross Vitória × Brasil-303, and 0.818 and 0.481 respectively, for the cross Babá × Elisa. In both crosses, both early and late-flowering transgressive segregants were obtained. Genetic gains based on selection of late flowering transgressive segregants in the F₂'s were estimated to be 10.2 days in Vitória × Brasil-303 cross, and 8.7 days in the Babá × Elisa cross. This revised version was published online in August 2006 with corrections to the Cover Date.