The pattern of C14 carbohydrate translocation and distribution from source leaf to various plant parts in watermelon grown in the greenhouse and field was investigated. Seedling-grown plants were pruned to have two branches with only one of them carrying a fruit. When leaves at four different positions (on fruit-bearing node, on fifth node above and below it, and on fifth node from the base of the non-fruit-bearing stem) were exposed to 14CO, the distribution of C142 compounds to different parts (fruit, stem, leaf, root) of the plant varied. In all treatments, the fruit was the strongest sink, followed by stem, leaf and root tissues. The highest percentage of C14 photo-assimilates was transferred out of the source when the leaf borne on the fruit-bearing node was exposed to 14CO2 in both greenhouse and field grown plants. Translocation of C14 compounds from the leaves on the fifth node above and below the first fruit-carrying node was similar. Only 29% of C14 was transferred from the source leaf borne on the fifth node of the non-fruit bearing branch in the greenhouse, as compared to more than 46% of C14 from other source leaves. Accumulation of C14 in the root tissues was highest when source leaves were borne on the non-fruit bearing branch. In general, field-grown plants had higher percentages of C14 translocated as compared to greenhouse-grown plants.
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