Physiological aspects of domestication in diploid wheat

Summary

A comparative study of photosynthetic response to water stress was conducted with one genotype of wild einkorn (Triticum boeoticum, W) and one of domesticated einkorn (T. monococcum, C).

Per unit leaf area, W showed a better performance for photosynthetic and transpiration activities, even under dry air and dry soil conditions. Its leaf water potential was always higher than that of C at any level of soil water potential. The difference in photosynthetic recovery from severe drought between W and C was also obvious. The photosynthetic rate, transpiration rate and water status of the leaves observed at 20 h after rewatering was almost the same as non-stressed leaves in W, whereas in C the photosynthetic rate was about half that of the non-stressed leaves, which was accompanied with a low transpiration rate and a high gas diffusion resistance. The ability of W to maintain a proper water balance over a wide range of soil water potential and to recover rapidly from severe drought seems to be a result of adaptation to its hard habitats.

However, under favourable water supply, the photosynthetic rate per unit leaf nitrogen was higher in C than in W. This may be advantageous to bring about a better plant growth than W on the arable land where the improved water supply is guaranteed.