Net Photosynthesis, Dark Respiration, Stomatal Conductance, Specific Leaf Weight, and Chlorophyll Content of Strawberry Plants as Influenced by Fruiting

Abstract

In an initial experiment, ‘Tribute’ (day-neutral) and ‘Allstar’ (June bearing) strawberry [ Fragaria × ananassa (Duch.)] plants were grouped into fruiting, partially deblossomed, and deblossomed treatments. Net photosynthesis (Pn), dark respiration (Rd), and stomatal conductance for CO 2 (g s ) were measured at 14-day intervals during the 1st fruiting cycle of both cultivars and at 7-day intervals during the 2nd fruiting cycle of ‘Tribute’. Pn of recently expanded leaves of fruiting plants was greater than that of deblossomed plants only during the 2nd week of the first fruiting cycle and the 2nd and 3rd weeks of the 2nd fruiting cycle. There were no differences in Rd or g s among treatments. At the end of the fruiting cycles, leaves, crowns, and roots of deblossomed plants of both cultivars had greater dry weights than those of fruiting plants. At the end of the first fruiting cycle, roots of deblossomed ‘Tribute’ had a higher percentage of total nonstructural carbohydrates (TNSC) than roots of fruiting plants. In Expt. 2, ‘Tribute’ plants were grouped into fruiting and deblossomed treatments. At 7-day intervals throughout the fruiting cycle, Pn, specific leaf weight (SLW), and chlorophyll content were determined for a leaf that was fully expanded at bloom (old leaf) and for the most recently expanded leaf (young leaf) of each plant. Pn of the young leaf was greater for fruiting plants than deblossomed plants only during weeks 5 and 6 of the fruiting cycle, and no treatment effect was observed for old leaf Pn. During fruit maturation, SLW was higher for deblossomed plants than fruiting plants for both leaf ages. Deblossomed plants had a higher leaf chlorophyll content than fruiting plants during the 1st, 2nd, and 4th weeks of the fruiting cycle.