Manner of Apical Meristem Destruction Affects Growth, Reproduction, and Survival of Sea Oxeye Daisy

Although herbivory may result in plant death, the mode and timing of damage may produce variable wounding responses in the attacked plant. In this study, effects of different types of apical meristem damage on growth and performance of sea oxeye daisy Borrichia frutescens (L.) DC were compared. Damage involved either clipping or galling of the apical meristem by the gall midge Asphondylia borrichiae Rossi and Strong. Apical dominance was relatively weak before flowering and stronger in short ramets that were shaded by taller neighbors later in the season. Clipped ramets delayed sprouting new stems, and galled ramets sprouted new stems quickly compared to intact ramets, but final stem counts were similar across treatments. Clipping significantly delayed flowering, reduced seed head ripening time, and resulted in fewer seed heads and seeds. Galling did not significantly impact reproduction compared to intact ramets. Nitrogen supplementation significantly increased stem count and seed count and lengthened seed ripening time. Borrichia frutescens responds differently to clipping versus galling by A. borrichiae and better tolerates galling in terms of nonreproductive performance and survival. Galling from A. borrichiae likely prevents Borrichia frutescens from flowering, which suggests resource regulation of meristems by the midge.

DARK FIXATION OF C14O2 BY OBLIGATE AND FACULTATIVE SALT MARSH HALOPHYTES

After dark fixation of C14O2 by salt marsh obligate halophytes, most of the 80% ethanol-soluble label appeared in the amino acid fraction. Species tested were Batis maritima L., Salicornia europaea L., Salicornia virginica L., and Borrichia frutescens (L.) D.C.A time study was made of the dark fixation products of C14O2 by Spartina alterniflora Loisel, a facultative halophyte, cultured with and without NaCl in the nutrient medium. In this species the greater proportion of label was recovered from amino acids (principally aspartic and glutamic acids) at times of 1 hour and less, the pattern changing to favor organic acids at longer times, mainly malic acid in NaCl-free plants. The shift to organic acids was slower in plus NaCl plants with aconitic and an unidentified acid appearing along with malic as the principal labelled acids.NaCl reduced the rate of C14O2 assimilation by Spartina alterniflora. Initially, the fixation pattern resembled that of obligate halophytes, becoming more like that of terrestial plants (glycophytes) after 1 hour.