Leaf CO2 gas exchange parameters has been reported of the Hungarian energy grass (Elymus elongatus (Host.) Runemark subsp. ponticus [Podp.] Melderis cv.) at the early stage of its life trait. Plants were grown in experimental field and growing pots, in situ CO2 gas exchange parameters were measured on the upper fully expanded leaves of significant vegetative phenophases using a portable IRGA
... [Show full abstract] system. Net photosyntetic rate (An), assimialtion capacity (Amax) and stomatal conductance for carbon-dioxide (gs) as the measures of assimilation were calculated. Displaying our results daily courses of the net assimilation to abiotic environmental parameters were constructed. Remarkable values of An-PAR curves (light compensation point, assimilation capacity) of the Hungarian energy grass were calculated and compared to other grasses to characterize its relative biomass potentialities. According to our results light showed closest correlation with the net photosynthetic rates overall. Compensation points were suitably low for positive assimilation rates in the light periods. Assimilation patterns through the phenophases by Amax slightly differed in the experimental sites owing to different abiotic environmental conditions. There was a correlation between stomatal conductance and photosynthetic rate consequently, so this proved to be a mediately regulatory environmental factor. Progressing with the phenophases illumination had a permanently decreasing, stomatal conductance had an increasing role for the regulation of the assimilation. In comparison with C3 agricultural grasses and other energy crops, potential assimilation of Hungarian energy grass will surely be appropriate to have good biomass production and be a carbon-dioxide sink for the environmental CO2 balance.