Growth and leaf physiology of sun- and shade-grown Sargent viburnum (Viburnum sargentii K.) "Onondaga" potted plants.

Abstract: To verify the effects of reduced light intensity on plant growth and on selected morphological and physiological characteristics of the leaves, 50 uniform two-year-old, asexually propagated plants of Viburnum sargentii 'Onondaga' were subjected to two shading levels (52 and 14% of the full solar radiation) for the entire growing season. A third group of 25 plants was grown in full sun and used as control. No differences were found in terms of leaf gas exchange, while leaf chlorophyll content was lower in the full sun-grown plants. A significantly higher chlorophyll a/b ratio was also found in this plants. Leaves were smaller in the heavy-shaded plants, which also showed a lower weight and specific leaf weight (leaf weight/area ratio). These plants also showed a reduced growth for all the parameters considered, while no differences were found between the full sun-grown plants and the mid-shaded ones. Based on our results, V. sargentii, though classified as a facultative shade species, can also be used in full