Flower development of the Chinese gooseberry (Actinidia chinensis Planch.) and some factors influencing it : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science
A study has been made of flower development in the Chinese gooseberry (Actinidia chinensis) and the effects of various environmental factors on that development . As well, the flower distribution patterns of various staminate vines and pistillate cultivars were surveyed.
Flower initiation in the Chinese gooseberry takes place late in the seasonal cycle, occurring just before the resumption of shoot growth in the spring (mid-late September). Once initiation commences, development of the flower structure is rapid and, like that of other angiosperms, staminate
and pistillate flowers develop from a potentially henrB.phrodite prinordium. Lateral flower buds are initiated in both pistillate and staminate cultivars, giving a compound dichasium. In some pistillate cultivars
(especially Hayward) however, many of these lateral flower buds cease development soon after their initiation and abort.
Chilling studies with cuttings showed that the Chinese gooseberry does not have an absolute lON temperature requirement for flowering, although chilling does enhance flowering by preventing the premature abortion of flower buds. There is also a low chilling requirement for bud break which chilling enhances; buds are in a state of dormancy over the winter, ie. bursting apparently being prevented by unfavourable conditions.
Defoliation, shading, and tipping treatments on newly emerging shoots were found to exemplify patterns of growth. Floral development in single node cuttings was enhanced by continuous defoliation, inhibited by severe shading, and unaffected by tipping. Leaf production and growth, shoot elongation and thickening, and new bud developrrent were also affected by such treatments.
These effects, were generally related to the severity of the treatment and to the length of time the treatments were applied. Similar treatments on individual shoots on vines in the field had little effect on reproductive growth possibly due to the translocation of assimilates to and from the treated shoots. The effects of chilling, defoliation, shading, and tipping are discussed in terms of hormonal, carbohydrate and nutritional responses.
A survey of the flowering characteristics of 14 unnamed staminate vines of unknown origin showed that these fell into 3 groupings, none of which were similar to the cultivars Tomuri and Matua. A similar survey of pistillate cultivars showed that there were also distinct differences in number of flowers per axil, numbers of flowering axils per shoot, and numbers of flowering shoots per lateral.