SHOOT AXILLARY BUD MORPHOGENESIS IN KIWIFRUIT (ACTINIDIA-DELICIOSA)

The annual cycle of kiwifruit [Acrinidia deliciosa (A. Chev.) C. F. Li ang et A. R. Ferguson var. deliciosa cv. Hayward] shoot axillary bud ( first-order axillary bud, FOAB) morphogenesis is described. FOABs deve loped quickly with the majority of bud scales and leaf primordia prese nt approx. 125 d after budbreak (dab). Mature FOABs had, on average, 2 3.2 bud scales and leaf primordia. Most second-order axillary structur es were also present approx. 125 dab. During the growing season, the s econd-order structures developed into second-order axillary buds (SOAB s) or remained as simple, dome-shaped meristems (SDSMs). At maturity, nearly all FOABs had four SOABs and, on average, 12.4 SDSMs. Most SDSM s were fused to the subtending leaf primordia, but some SDSMs develope d so that they were 'free' from the subtending leaf primordia. Third-o rder axillary meristems (third-order SDSMs) were observed in the axils of most SOABs, and, on average, there were 20.6 per FOAB. Our observa tions on the development of second-order axillary structures are consi stent with evocation in kiwifruit occurring earlier than the generally -accepted time of late summer. (C) 1997 Annals of Botany Company.