Net photosynthesis, stomatal conductance, chlorophyll content and specific leaf weight of pistachio trees (cv. Aegenes) as influenced by fruiting

Abstract

SUMMARYNet photosynthesis (Pn), stomatal conductance (gs) and chlorophyll content (chl) were measured on fruiting and nonfruiting pistachio trees (Pistacia vera cv. Aegenes) in 1991 and 1992. Specific leaf weight (SLW) was also measured in 1992. Measurements were taken at frequent intervals from May to September in 1991 and from April to August in 1992. Pn, gs and chl in fruiting trees were greater than in nonfruiting ones from the begin-ing of measurement until mid-June in both years. From mid-June onwards, Pn and gs started to decrease slightly but were approximately the same in fruiting and nonfruiting trees. Chlorophyll (a/b) was similar for fruiting and nonfruiting trees throughout the period of measurement. Although no significant differences were found in SLW between leaves of fruiting and nonfruiting trees, SLW was higher in fruiting than nonfruiting trees until the end of May, after which this relationship was reversed. The results showed that fruiting affected chl, gs and Pn rates from early in the season until mid-June, the period which precedes the onset of bud abscission and seed growth.