Differences in Water and Assimilate Fluxes in Tomato Fruits among Cultivars, and Relationships with Fruit Yield and Soluble Solids Content

Abstract

Fruit growth represents the balance between material influxes via xylem and phloem and efflux by transpiration via the stomata of the calyx and cuticle of fruit, which determines the yield and soluble solids content (SSC). Knowledge of these factors is important for the production of high-SSC tomato fruit, but no physiological indicator is available to allow prediction of fruit yield and SSC for breeding and crop production purposes. To identify indicators, we grew Japanese, Dutch, Japanese × Dutch, and high-SSC cultivars and sought correlations of the fluxes to fruit with yield and SSC. To estimate the contributions of the xylem, phloem, and transpiration fluxes to fruit weight increase, we measured 2-day growth rates of intact, detached, and heat-girdled (peduncle steamed for 90 to 120 s) fruits treated at 14, 28, or 42 days after flowering (DAF). Xylem influx was much lower in the high-SSC cultivar than in the others. Phloem influx was lower in the Dutch and hybrid cultivars at 28 DAF. Transpiration efflux was greater in the Japanese cultivar at 42 DAF. Fruit growth rate at 14 DAF was positively correlated with yield, and phloem influx per fruit weight increase at 14 and 28 DAF was positively correlated with SSC. These results show how the xylem, phloem, and transpiration fluxes of fruit can predict fruit yield and SSC. This information will help the production and breeding of high-SSC fruit.

Modelling grape growth in relation to whole-plant carbon and water fluxes

“…In fleshy fruits such as grape, which accumulate high concentrations of soluble sugars, carbon fluxes may also influence water flux by altering water potential gradients between the plant and fruit through changes in fruit osmotic potential (Coombe, 1992; Wada et al , 2008, 2009; Keller and Shrestha, 2014; Zhang and Keller, 2017). Therefore, it is essential to investigate the regulation and co-ordination of water and carbon fluxes during expansive growth as they determine fruit yield and their ratio largely determines fruit composition, such as sugar concentration (Guichard et al , 2001; Nardozza et al , 2017; Kawasaki and Higashide, 2018).…”