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  • Author or Editor: Han Ping Guan x
  • HortScience x
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Light/dark effects on growth and sugar accumulation in tomato fruit were studied on intact plants (in vivo) and in tissue culture (in vitro). Similar patterns of growth and sugar accumulation were found in vivo and in vitro. Fruit growth in different sugar sources (glucose, fructose or sucrose) showed that sucrose was the primary carbon source translocated into tomato fruit. Darkening the fruit decreased growth about 40% in vivo and in vitro: Light-grown fruit took up 30% more sucrose from the same source and accumulated almost twice as much starch as that in dark-grown fruit. The difference in CO2 exchange rate between light and dark indicated that light effects on fruit growth were due to mechanisms other than photosynthesis. Supporting this conclusion was the fact that light intensities ranging from 40 to 160 μmol/m2/s had no influence on growth and light did not increase growth when fruits were grown on glucose or fructose. A possible expansion of an additional sink for carbon by fight stimulation of starch synthesis during early development will be discussed.

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