[Effects of salt stress on growth, photosynthetic and fluorescence characteristics, and root architecture of Corylus heterophylla ×C. avellan seedlings].

We examined the effects of different salt stress intensities (control, mild, moderate, severe) on the growth traits, photosynthetic and fluorescence characteristics, and root architecture of three Corylus heterophylla × C. avellan varieties (Xinzhen 1, Xinzhen 2, Xinzhen 3). The results showed that the new shoot length, basal diameter, leaf area, root biomass, shoot biomass, leaf biomass, and total biomass of the three varieties all decreased, but the root-shoot ratio increased with increasing salt stress. The net photosynthetic rate of the three varieties in the moderate and severe salt stress treatments significantly decreased by 20.5% and 43.2%, respectively. The transpiration rate and stomatal conductance in the mild, moderate, and severe salt stress treatments decreased by 2.0%, 16.3%, 32.0% and 10.2%, 35.7%, 60.1% than those of the control, respectively. With the increasing salt stress, the intercellular CO2 concentration gradually increased, while the water use efficiency increased first and then decreased and being the highest in the mild salt stress treatment. The initial fluorescence of the three varieties increased with the increasing salt stress. With the increasing salt stress, the maximum fluorescence, maximal photochemical efficiency, potential photochemical activity, actual photochemical efficiency, electron transfer rate and photochemical quenching coefficient decreased, while the non-photochemical quenching coefficient increased first and then decreased. Salt stress reduced root biomass, length, surface area and volume of the three varieties. In the same salt stress treatment, the reduction of root architecture parameters of Xinzhen 2 was lower than the other two varieties. The growth traits, photosynthetic and fluorescence characteristics, and root architecture parameters of Corylus heterophylla × C. avellan were affected by both varieties and salt stress. Xinzhen 2 displayed stronger growth and photosynthetic physiological adaptability to salt stress, showing stronger salt tolerance than the other two varieties.