Effect of Carbon Dioxide Enrichment on Vine Growth and Berry Quality of ‘Kyoho’ Grapes

Abstract

Although ambient temperature is kept adequate, grape cultivation under covered facilities during winter months in Japan gives rise to low yields of poor quality berries because of low light intensities. This investigation was conducted in leaf chamber, using Vitis labruscana Bailey cv. Kyoho, to determine the influence of leaf age, light intensity, and CO₂ concentrations on photosynthesis. The effects of CO₂ enrichment on vine growth and fruit quality were also investigated in growth chambers.
1. The rate of photosynthesis per unit leaf area (Pn) between May 28 and September 19 rapidly increased with leaf growth, reaching a maximum of 18.9mg CO₂/dm²/hr, 37 days after the unfolding of a leaf. Pn then gradually decreased with leaf age. In young leaves, higher CO₂ concentrations and stronger light intensities resulted in a significant increase in Pn. Older leaves exhibited a similar enhancement of Pn upon exposure to high light intensity. Pn was saturated at 828ppm CO₂.
2. Administration of 1, 000 to 1, 100ppm CO₂ to vines for an 8hr/day at a late stage of berry development until harvest had no effect on berry size but resulted in an increase in sugar and anthocyanin contents but a decrease in organic acid content. Dry weight of newly developed roots doubled as a result of CO₂ enrichment.
3. Application of CO₂ under a long-day photoperiod at an early stage of berry development to a week before véraison markedly promoted shoot elongation. Furthermore, CO₂ enrichment gave a 36% increase in both berry and cluster weights and also a higher sugar-acid ratio at harvest.