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Subject: search.filters.subject.Kiwifruit growth

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    Resource allocation in kiwifruit (Actinidia chinensis) : a thesis presented in partial fulfilment of the requirements for the degree Doctor of Philosophy in Plant Physiology at Massey University, Albany, New Zealand
    (Massey University, 2012) Boyd, Linda
    Kiwifruit growers in New Zealand receive financial incentives to produce high yields of fruit with high individual dry matter concentrations (DMCs). Several vine management techniques are available to growers to enable them to direct more resources into production of fruit rather than into other sinks such as root growth and shoot extension. The long term consequences of these management techniques are not well understood. The overall objective of the work described in this thesis was to investigate how manipulating whole vine source-sink relationships affects fruit quality, long-term vine health and productivity in ‘Hort16A’ kiwifruit vines. A compensatory reduction in flower numbers occurred as a result of whole vine carbohydrate depletion (famine treatment) and producing high crop loads of high DMC fruit with reduced leaf area (minimal pruning, standard nitrogen). Keeping crop loads low did not result in increased productivity, instead additional resources were allocated to root growth (feast treatment). Isolating the canopy from the roots by extended trunk girdling was the technique that enabled high flower numbers to be maintained across seasons. Increasing individual fruit DMC generally enabled fruit to be harvested earlier than fruit with lower DMC. This was because flesh colour change, the main harvest criterion, occurred earlier in fruit from treatments where DMC was increased. Fruit softening behaviour was less affected by changes in DMC than flesh colour change, meaning that low DMC fruit could be softer at commercial harvest that more mature high DM fruit. The implications of this finding for storage performance were discussed. Vines showed few of the common responses to carbohydrate depletion. There was no evidence of increased individual leaf area, reduced specific leaf weight, upregulated leaf photosynthesis or increased shoot growth. Uptake and allocation of some mineral nutrients within the vines was affected, but few visible signs of leaf nutrient deficiencies were seen. The results suggest that vines respond to carbon depletion primarily be altering resource allocation between flowering and root growth, rather than by altering its ability to capture carbon.
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    Aspects of growth control in kiwifruit and blackcurrant : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University
    (Massey University, 1979) Lawes, George Stephen
    This study emphasized the interplay of several types of growth regulator in the control of growth and development in the kiwifruit plant. Hence different parts of the plant are seen to contribute to this control, the plant appearing as a fully-integrated system with the shoots and roots interacting with each other. The gibberellins were active in the promotion of stem elongation, and it is considered stem growth is dependent on the photosynthate supply, and that this is mediated by the growth regulators. A leaf had a dominant effect on internode growth, and therefore shoot length, at a very early stage of its development - but the effect of an individual leaf was very localised. The plant roots were not clearly shown to be essential for breaking dormancy, bud burst, or early shoot growth. However it was found the roots could be supplying gibberellins as one of the factors required to maintain normal shoot growth. Cytokinins for early bud growth could have been supplied in the bleeding sap either from the roots or the stem tissue. Reservations are expressed about the need for high spring sap flows for plant growth. High sap flows may be a result of a combination of circumstances at the time, and not a necessary pre-requisite to growth. SADH and maleic hydrazide are effective shoot growth retardants, and may find commercial acceptance, except their apparent effect in enhancing post-harvest fruit respiration must receive further study. Bud dormancy was greatest before leaf fall, and dormancy was broken by about 700 hours below 7.2°C, although warm temperatures were just as effective in overcoming this dormant condition. Winter dormancy appeared to be basically the same type of condition as correlative inhibition, and it is suggested that each is, in large part a result of an inability to utilise cytokinins or other growth promoters. It is considered that the juvenile-like condition in blackcurrant is distinct from true juvenility,and the former did not appear to be the result of proximity to gibberellins from the roots. Further, it could not be shown for true juvenility that it was likely to be due to the production of inhibitory levels of gibberellin by the roots.
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    Source-sink relations in kiwifruit : carbohydrate and hormone effects on fruit growth at the cell, organ and whole plant level : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Physiology and Horticultural Science at Massey University, Palmerston North, New Zealand
    (Massey University, 1997) Currie, Michael Brian; Currie, Michael Brian
    Fruit weight of Actinidia deliciosa, A. chinensis. and A. arguta kiwifruit was correlated with fruit cell number and seed numbers or seed weight within and between species. Reducing seed number of A. deliciosa 'Hay ward' by style excision reduced fruit weight and cell size, but had only minor effects on cell number. It is suggested that the impact of genotype on fruit weight was by determining the number and size of ovules available to be fertilised and form seeds. At a leaf:fruit ratio of four, girdling of lateral shoots increased fruit weight mainly due to increased cell expansion. Fruit cell numbers were also increased when girdles were applied during post-anihesis cell division. Girdling of individual canes with a high leaf:fruit ratio also increased mean fruit weight. However when more canes were girdled on a vine, the response to girdling was decreased, and fruit weight in non-girdled canes was lower. These negative effects on fruit growth were not due to reduced root function or increased competition for photo-assimilate. Increased cane girdling resulted in a transitory increase in the concentration of cytokinins extracted from girdled canes, and this was correlated with increased bud-burst. The increased vegetative growth may have inhibited fruit growth on girdled canes, but no explanation was found for the reduced fruit weight in non-girdled canes. An inhibitory effect of high seeded kiwifruit on the growth of low seeded kiwifruit was confirmed, and could be accounted for by increased seed abortion from inhibited fruit. Diffusible IAA from kiwifruit increased over time, but was not associated with inter-fruit competition or fruit seed number. Application of the auxin transport inhibitor N-l-naphlhylphthalamic acid (NPA) to kiwifruit pedicels after fruit set, reduced fruit fresh weight and dry matter accumulation. However late NPA application had no effect on fruit weight, which suggests that IAA transport is not essential for kiwifruit growth at all times. Application of N-(2-chloro-4-pyridyl-N'-phenylurea (CPPU) to A. deliciosa and A. chinensis kiwifruit selections increased fruit weight, but application of adenine based cytokinins in combination with CPPU increased fruit weight further. CPPU application resulted in a transitory decrease in fruit abscisic acid levels.