Dry Matter Partitioning and Assimilation in Fruiting and Deblossomed Strawberry

Abstract

Abstract Day-neutral strawberries (Fragaria × ananassa Duch. ‘Brighton’) were grown in a greenhouse and either continuously deblossomed or allowed to fruit over a 50 day period. Total plant dry weight was essentially the same in both treatments throughout this period. During a 25-day-period, the fruit truss was the predominant sink and, for about 9 days, fruit growth rate exceeded that of the whole plant, and the growth rates of other plant parts were reduced to zero. At the end of the study, fruiting plants had accumulated 16 g dry weight in fruit and had 62%, 53%, and 44% less dry matter in roots, crown, and leaf blades than deblossomed plants. The starch content of roots, crown, and leaf blades of deblossomed plants was about 18-, 7- and 4-times higher than plants with fruit. Fruiting reduced stolon, inflorescence, and branched crown emergence by 80% or more. Leaf area was not affected significantly by treatments, but specific leaf weight of deblossomed plants was as much as 44% higher than that of fruiting plants. Fruiting did not have a significant effect on unit leaf rate. Net photosynthetic rates of leaves which emerged with the 1st inflorescence were similar in both treatments before rapid fruit growth; thereafter, photosynthesis of comparable leaves was 60% to 80% higher in fruiting than deblossomed plants. The presence of fruit also increased stomatal and mesophyll conductance by 40%. The increase in root system in a finite soil volume may have affected assimilation by deblossomed plants adversely. These results show that strawberry fruit strongly inhibit starch accumulation and growth of vegetative parts, while maintaining or enhancing photosynthesis.