Vol. 70 No: 5

Title:
The Seasonal Cycle of Leaf, Shoot and Bud Development in Kiwifruit

Author:
ANGELA M. SNOWBALL

pp: 787-798

Abstract:
This study describes the cycle of leaf growth and shoot growth, and of shoot bud development on those shoots, from inception in early spring through to elongation the following spring. To describe the key developmental events, measurements of shoot length, leaf number, leaf area and counts of flower number were made on shoots in the field. Microscopic examination of shoot buds was carried out periodically in the laboratory. Buds were dissected, and the numbers of leaves, axillary primordia, and basal buds within each bud assessed. The field study was carried out using four populations of shoots, at two sites and in two seasons to verify the observed trends. Spring-breaking shoots grew from mid-September (bud break) to mid-summer, summer-breaking shoots grew from early January (bud break) to early April. Summer-breaking shoots were longer and had larger leaves than spring-breaking shoots. Shoot buds began to develop as the shoot began to elongate, they contained several leaf initials when the shoot was at bud break. By mid-January shoot buds on spring-breaking shoots contained 20–22 leaves. Buds reached a maximum size at approximately the same time as the subtending leaves ceased growth. Axillary primordia appeared in buds on spring-breaking shoots in mid-November. Buds contained a maximum of 3–4 basal buds and 9–12 axillary primordia at the sites of next year's flowers. Shoot buds at nodes 7–12 wereexamined in detail as these are some of the earliest buds to develop and also some of the largest buds. These buds continued to grow for several months after their subtending leaves reach full-size. Maximum numbers of leaves and axillary structures were achieved within the buds at similar times. Buds at nodes 7–12 on shoots in all populations were morphologically similar, with terminal buds tending to be slightly smaller than other buds. In the following spring, between 97 and 99% of buds elongated to become floral shoots, with between three and five flowers per shoot.

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