Field assessment of photosynthetic characteristics in micropropagated and grafted wych elm (Ulmus glabra Huds.) trees

A field test of wych elm (Ulmus glabra Huds.) trees micropropagated in tissue culture was established to compare their photosynthetic characteristics with those from control grafted scions. Measurements were made at the sixth growing season after planting. The results showed similarities between the two stock types in terms of height, diameter at breast height, and leaf morphology. Grafted trees, which were markedly less rejuvenated than micropropagated trees, performed better in many of the light absorption and leaf gas exchange attributes including maximum CO(2) assimilation rate at saturating photosynthetic photon flux density (P (max)), apparent quantum yield of photosynthesis (alpha), transpiration rate (E), and stomatal conductance (g (s)). In the grafts, the direct effect of photosynthesis could be clearly identified by a significantly lower specific leaf area and a higher content of leaf dry mass. Chlorophyll a fluorescence parameters showed non-stressed growth patterns in both stock types. Rates of the maximal photochemical efficiency of photosystem II (F (v)/F (m)), potential electron capacity ('area'), and variable-to-initial fluorescence ratio (F (v)/F (0)) were higher in micropropagated elms. Findings from this study indicate that micropropagated elm stock is ready for testing on a larger scale.