An instrument for measuring kiwifruit size

Abstract

Abstract An instrument designed for easy field measurements of kiwifruit volume or weight is described. Volume (or weight) calculated from a single length measurement has a resolution of ± 1 cm3 (g) permitting individual fruit growth to be monitored on a weekly basis. The assumption that the density of kiwifruit is 1 gm/cm3 is shown to be a very good approximation. Variations in fruit shape cause the average error in a single measurement to be 8%. Data collected are displayed with resolutions of 1 cm3 (g) for operator verification and are transferable to a portable personal computer to simplify data storage and analysis and to minimise handling errors. With this arrangement, a single operator can measure over 2 500 fruit in 4 h. The use of fruit growth information for assessing orchard practices such as irrigation management and for the early prediction of harvest fruit size in relation to target yield is discussed.