Genetic variation and genotype by environment interaction for heat tolerance in crisphead lettuce

Authors: LAFTA, ABBAS - North Dakota State University; SANDOYA, GERMAN - University Of Florida; Mou, Beiquan

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2020
Publication Date: 12/18/2020
Citation: Lafta, A., Sandoya, G., Mou, B. 2020. Genetic variation and genotype by environment interaction for heat tolerance in crisphead lettuce. HortScience. 56(2):126-135. https://doi.org/10.21273/HORTSCI15209-20.
DOI: https://doi.org/10.21273/HORTSCI15209-20

Interpretive Summary: Climate change is anticipated to negatively impact crop production and ultimately decrease global food production. Lettuce (Lactuca sativa L.) is a cool season crop and vulnerable to high temperature stress which promotes early stem elongation (bolting) and decreases yield and quality. Therefore, it is important to identify lettuce varieties with tolerance to high temperatures to ensure production of high quality lettuce. We evaluated the performance of 25 iceberg lettuce cultivars for their tolerance to high temperature stress in three historically important lettuce production areas of California that differ in their temperature regime and planting seasons. Genetic variation was identified for yield and related traits of iceberg lettuce grown in warmer conditions. Most of the variation can be attributed to the environmental differences. The cultivar Primetime appears to be a good source of heat tolerance for iceberg lettuce as it produced the highest yield across warmer conditions and exhibited other desirable characteristics in these environments. These results are helpful for growers to choose cultivars for hot environments and for breeders to develop new heat-tolerant lettuce cultivars.

Technical Abstract: Lettuce (Lactuca sativa L.) is a cool season crop that is vulnerable to high temperature stress, which promotes bolting and decreases yield and quality. It is anticipated that climate change may lead to higher temperatures in current lettuce growing areas in the U.S., thereby negatively impacting lettuce production and possibly resulting in adverse impacts on global food production. Therefore, it is important to identify lettuce germplasm with tolerance to temperatures higher than those that have occurred over the past century. Thus, we evaluated 25 crisphead lettuce cultivars for tolerance to high temperature stress in the San Joaquin, Imperial, and Salinas Valleys, CA. Genetic variation was identified for yield and traits, such as core length, head diameter, tipburn, bolting, and market maturity, of crisphead lettuce grown in warmer conditions. Significant genotype × environment interaction did not account for most of the variation; the main differences were found for environments and only a small proportion of the variation was due to genotypes. Cultivar Primetime is a good source of heat tolerance for crisphead lettuce as it presented the best yield and exhibited other desirable characteristics across warmer conditions. These results provide insight on the cultivars that respond well to hot environments. Moreover, the data can be used by breeders to develop new heat-tolerant lettuce cultivars.