Variability of photosynthetic and related traits in maize and other summer crops in a temperate humid area

Photosynthetic rate and water use efficiency (WUE) are crucial for the sustainable use of water in agriculture. Our objective was to analyze the variability of photosynthetic and related traits in maize (Zea mays L.) and other summer crops in a temperate humid area. We evaluated photosynthetic parameters in maize for three years and compared them to pigeonpea and chickpea, adapted to arid environments, and pepper, tomato and common bean, as irrigated crops. Variability was significant in maize for most photosynthetic parameters and no consistent patterns of variability were found among genotypes. Compared to other crops, maize (C4 crop) had the highest CO2 assimilation and WUE, and the lowest stomatal conductance, substomatal CO2 concentration, and transpiration. CO2 assimilation was lowest for chickpea, stomatal conductance was highest for pigeonpea, substomatal CO2 concentration was highest for tomato and pigeonpea, transpiration was highest for pigeonpea, and WUE was lowest for pigeonpea. Chickpea lacked variability for photosynthetic traits, while pigeonpea has the largest potential for improving photosynthetic traits. Net assimilation, conductance, and transpiration could be improved in common bean, and substomatal CO2 concentration in pepper. Water Use Efficiency could be improved in some C3 crops, but more genetic biodiversity has to be identified in maize.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was funded by the Spanish Ministerio de Innovación y Universidades (MCIU), the Agencia Estatal de Investigación (AEI) and the European Fund for Regional Development (FEDER), UE (project code PID2019-108127RB-I00).Peer reviewe