Reproductive development of blackberry (Rubus cuneifolius), as influenced by ozone

The effects of ozone on reproductive development of blackberry (Rubus cuneifolius) in situ are reported here and, in particular, changes over time of flower and fruit production, and the size and time to maturity of fruits produced. Blackberry, a common associate in early successional communities in the southern USA, was exposed to subambient, ambient (both chambered and nonchambered plots) and elevated (2x ambient) ozone concentrations for two growing seasons (1994-95). Competition from other plant species was not excluded, and reproductive development was examined in April-May of the second year on the floricanes. An initial acceleration in flowering resulted from exposure to elevated ozone with more flowers initiated and peak production occurring sooner than all other treatments. Total numbers of fruits were not significantly different among treatments. Numbers of large and ripe fruits were greatest in carbon-filtered and unfiltered chambers and least in the 2x and ambient air treatments. Possible implications related to changes in community structure and function are discussed.