LAUSR

With the aggravated abiotic stresses due to climate change and burgeoning population, a better understanding of crop responses to multiple stresses are needed to secure the crop production. The effects of individual climatic factor on crops were well documented, while the interaction of combined climatic factors received less attention. The frequency of salinity and waterlogging stress is increasing, which will be accompanied by elevated CO2 concentration (e[CO2]). This study aimed to explore how these three climatic variables interacted and affected two tomato genotypes. Cultivated tomato (S. lycopersicum) and wild tomato (S. pimpinellifolium) were grown at ambient [CO2] (a[CO2]) and e[CO2], and then subjected to salinity, waterlogging, and combined stress besides control. Phenotyping of plants included leaf photosynthesis (Pn), chlorophyll fluorescence, quenching analysis, pigment and plant growth. The results showed that the response of tomatoes depended on both genotype and stress type. The photosynthesis of the cultivated tomato at salinity and combined stress were inhibited, while that of wild tomato at individual salinity, waterlogging stress and their combination decreased Pn. The e[CO2] increased both Pn and biomass of the cultivated tomato at salinity and combined stress compared with a[CO2]. Differences in response patterns between the two genotypes to individual and combined stress were observed in key parameters for both Pn and tomato growth. Hierarchical clustering and principal component analysis stated genetic variations of tomatoes responding to these three climatic factors. Understanding these interactive effects of salinity and waterlogging with e[CO2] in tomato will facilitate improvement of crop resilience to climate change.