Xylem vessel functionality during the maturation of 'Hayward' and 'Zesy002' kiwifruit
As a fruit develops, water and solutes are transferred from the plant via the vascular system, which is comprised primarily of phloem and xylem vessels. The hydraulic connectivity of the xylem in the pedicel has direct implications for the development and quality of the fruit at harvest. Additionally, xylem conductivity at harvest may also affect the postharvest performance of fruit (e.g., sap exudate from the picking wound and associated pathogen growth). Despite this knowledge, little is known of how xylem functionality changes as a kiwifruit matures. In the present study, two methods were used to examine the xylem functionality of both Actinidia chinensis var. deliciosa Hayward and A. chinensis var. chinensis Zesy002 pedicels and fruit that were sampled at different stages of maturity. Xylem functionality was assessed using a) uptake and transport of toluidine blue, a xylem specific dye, and b) through measurements of hydraulic conductance using a xylem flow meter. The relationship between xylem functionality and exudation was examined. Significant changes were observed in xylem functionality through the pedicel and across the receptacle as the fruit matured on the vine. Xylem conductance of the receptacle was significantly lower than in the pedicel in both cultivars. Over time, xylem conductance appeared to change, with an apparent reduction in functionality occurring before an increase in soluble solids accumulation in the fruit. The timing of the changes in xylem conductance in relation to fruit maturity of Hayward and Zesy002 can have implications for managing harvest.
Gould, N., Haisman, N. and Burdon, J. (2022). Xylem vessel functionality during the maturation of 'Hayward' and 'Zesy002' kiwifruit. Acta Hortic. 1332, 163-170
Actinidia, fruit, hydraulic conductance, pedicel, water, vasculature, xylem