Phenotyping from lab to field - tomato lines screened for heat stress using F-v/F-m maintain high fruit yield during thermal stress in the field

摘要

This study aimed to phenotype young tomato (Solanum lycopersicum L.) plants for heat tolerance by measuring F-v/F-m after short-term heat treatments in climate chambers and selected sensitive (low F-v/F-m) and tolerant (high F-v/F-m) cultivars to investigate their in-field performance. Twenty-eight genotypes were phenotyped at 40 : 28 degrees C for 2 days in climate chambers. A second screening (four high F-v/F-m and four low F-v/F-m genotypes) was conducted for 4 days at 38 : 28 degrees C, followed by 5 days' recovery (26 : 20 degrees C). The tolerant genotypes maintained high net photosynthesis (P-N) and increased stomatal conductance (g(s)) at 38 degrees C, allowing better leaf cooling. Sensitive genotypes had lower F-v/F-m and P-N at 38 degrees C, and gs increased less than in the tolerant group, reducing leaf cooling. Under controlled conditions, all eight genotypes had the same plant size and pollen viability, but after heat stress, plant size and pollen viability reduced dramatically in the sensitive group. Two tolerant and two sensitive genotypes were grown in the field during a heat wave (38 : 26 degrees C). Tolerant genotypes accumulated more biomass, had a lower heat injury index and higher fruit yield. To our knowledge, this is the first time screening for heat tolerance by F-v/F-m in climate chambers was verified by a field trial under natural heat stress. The differences after heat stress in controlled environments were comparable to those in yield between tolerant and sensitive groups under heat stress in the field. The results suggest that F-v/F-m is effective for early detection of heat tolerance, and screening seedlings for heat sensitivity can speed crop improvement.