Articles
THE EFFECT OF TEMPERATURE AND DEVELOPMENTAL STAGE ON CARBON DIOXIDE EXCHANGE OF ATTACHED ‘ROYAL GALA’, ‘FUJI’ AND ‘CRIPPS’ PINK’ APPLE FRUITS
Article number
903_150
Pages
1077 – 1084
Language
English
Abstract
In the Western Cape region of South Africa post-bloom spring temperatures can be high, resulting in high fruit respiration rates during a period when carbohydrate supply can be potentially limiting.
Chlorophyllous apple flesh tissues exposed to light are capable of assimilating CO2 diffusing through stomata or lenticels, or re-fixing CO2 lost through respiration.
This could represent a significant contribution to the carbon balance of growing fruits.
In this field study, light-saturated net CO2 assimilation rate (Amax), dark respiration rate (Rd), and light-saturated apparent photosynthetic rate (Pmax, the difference between Amax and Rd), were measured at different fruit surface temperatures on attached Royal Gala, Fuji and Cripps Pink apple fruits in the Ceres and Elgin regions (Western Cape, South Africa). Measurements were performed during the cell division stage (20-30 days after full bloom, DAFB) and during the cell enlargement stage (50-60 DAFB) of fruit growth.
In all cultivars, Pmax and Rd increased, and Amax decreased with increasing fruit surface temperature.
After the cell division stage, Pmax and Rd decreased and Amax increased with increasing fruit fresh weight. Fuji fruit reached compensation point (Amax = positive due to Pmax exceeding losses by Rd) during the mid-season (55 DAFB) at temperatures of up to 30°C, but Amax remained negative at 35°C. Royal Gala almost reached compensation at 20 and 25°C (53 DAFB), but Amax remained negative at 30 and 35°C. The rapid increase in dark respiration rate with increasing temperatures during the cell division stage of fruit growth creates a high demand for assimilates and could have serious implications for fruit growth and final size in warm climates such as the Western Cape.
Chlorophyllous apple flesh tissues exposed to light are capable of assimilating CO2 diffusing through stomata or lenticels, or re-fixing CO2 lost through respiration.
This could represent a significant contribution to the carbon balance of growing fruits.
In this field study, light-saturated net CO2 assimilation rate (Amax), dark respiration rate (Rd), and light-saturated apparent photosynthetic rate (Pmax, the difference between Amax and Rd), were measured at different fruit surface temperatures on attached Royal Gala, Fuji and Cripps Pink apple fruits in the Ceres and Elgin regions (Western Cape, South Africa). Measurements were performed during the cell division stage (20-30 days after full bloom, DAFB) and during the cell enlargement stage (50-60 DAFB) of fruit growth.
In all cultivars, Pmax and Rd increased, and Amax decreased with increasing fruit surface temperature.
After the cell division stage, Pmax and Rd decreased and Amax increased with increasing fruit fresh weight. Fuji fruit reached compensation point (Amax = positive due to Pmax exceeding losses by Rd) during the mid-season (55 DAFB) at temperatures of up to 30°C, but Amax remained negative at 35°C. Royal Gala almost reached compensation at 20 and 25°C (53 DAFB), but Amax remained negative at 30 and 35°C. The rapid increase in dark respiration rate with increasing temperatures during the cell division stage of fruit growth creates a high demand for assimilates and could have serious implications for fruit growth and final size in warm climates such as the Western Cape.
Publication
Authors
J.J.B. Pretorius, K.I. Theron, S.J.E. Midgley
Keywords
Malus × domestica, carbon balance, cell division stage, compensation point, fruit growth, fruit photosynthesis, heat stress
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