| Abstract: | Tomato fruit on plants grown in circulating nutrient solutionexhibited a diurnal cycle in growth rate, measured as a changein diameter, with a maximum during thc day. The diurnal growthcycle was less evident in those fruit grown at high electricalconductivity (17 mS), or on days of reduced irradiance. Girdledfruit of low conductivity plants grew at a much reduced ratewith a diurnal cycle in reverse to that of ungirdled fruit,while girdled fruit of high conductivity plants showed no diurnalgrowth. The evidence suggests that phloem and xylem water transportinto fruit operate on opposite diurnal cycles. Partitioning of available xylem water in detached fruit betweenthe calyx and berry, as well as within the berry, was determinedby berry size and relative humidity in the air. Although berrytranspiration rate was unaffected by conductivity treatmentduring plant growth, water uptake capacity was greatly reducedin the berry from high conductivity plants, suggesting an increasedresistance in the xylem transport system within the fruit. Key words: Salinity, electrical conductivity, tomato fruit, xylem transport, transpiration |
