New Zealand Journal of Crop and Horticultural Science abstracts
Influence of postharvest temperatures on leaf gas exchange, carbohydrate
reserves and allocations, subsequent budbreak, and fruit yield of ‘Braeburn’
apple (Malus domestica) trees
Dennis H. Greer1,*
Jens N. Wünsche2
Elizabeth A. Halligan1
1The Horticulture and Food Research
Institute of New Zealand Ltd
Palmerston North Research Centre
Private Bag 11 030
Palmerston North, New Zealand
2The Horticulture and Food Research
Institute of New Zealand Ltd
Hawke’s Bay Research Centre
Private Bag 1401
Havelock North, New Zealand
*Present address. School of Wine and Food Science, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia.
Abstract Potted ‘Braeburn’ apple (Malus domestica
(Borkh.)) trees were grown after harvest in four controlled temperature conditions
for 5 weeks to manipulate differences in carbohydrate reserves. Day/night
temperatures ranged from 24/19 to 9/4°C. On several occasions, leaf gas
exchange and soil respiration were measured and trees were destructively
harvested before and after treatment to measure biomass of component parts.
Samples were also taken for carbohydrate analysis. After treatment, the trees
were returned outdoors and budbreak and fruit growth were measured in the
following spring and crop load was measured at the next harvest. Trees at
24/19°C produced new leaves and flowered profusely whereas those at 9/4°C
senesced rapidly but these trees grew new roots. Photosynthesis and respiration
were highly dependent on temperature, and after 5 weeks of growth there were
marked differences in rates between the various treatments. Non-structural
carbohydrate concentrations declined in trees at all treatments but mostly
at 24/19°C. However, carbohydrate reserves increased in trees in all
treatments except at 24/19°C. Budbreak was delayed by up to 16 days in
the trees treated at 24/19°C compared to trees treated at 9/4°C but
treatment had no affect on fruit growth. Crop yields were highest in those
trees with highest carbohydrate reserves, providing some support for the
conclusion that high apple yields in New Zealand are dependent on elevated
carbohydrate reserves achieved by favourable photosynthetic conditions and
the extended growing season between harvest and leaf senescence.
Keywords Braeburn apple; budbreak; carbohydrates; crop load; photosynthesis; postharvest season; yield
H02011 Received 22 January 2002; accepted 5 July 2002; published 25 September 2002
New Zealand Journal of Crop and Horticultural Science, 2002, Vol. 30: 175-185
0014-0671/02/3003-0175 $7.00 © The Royal Society of New Zealand 2002
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