אסיף מאגר המחקר החקלאי

Effect of sink-source manipulations on the photosynthetic rate and carbohydrate content of cucumber cotyledons

Year:

1985

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Volume :

36

Co-Authors:

Mayoral, M.L., Division of Soils and Water, Agricultural Research Organization, P.O. Box 6, Bet Dagan 50250, Israel
Plaut, Z., Division of Soils and Water, Agricultural Research Organization, P.O. Box 6, Bet Dagan 50250, Israel
Reinhold, L., Division of Soils and Water, Agricultural Research Organization, P.O. Box 6, Bet Dagan 50250, Israel, Botany Department, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel

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Abstract:

Mayoral, M. L., Plaut, Z. and Reinhold, L. 1985. Effect of sink-source manipulations on the photosynthetic rate and carbohydrate content of cucumber cotyledons.-J. exp. Bot. 36 1551-1558.The photosynthetic rate of cucumber cotyledons (Cucumis sativus cv. Dahla) reached a maximum value of 12 mg dm-2 h-1, 10 d after emergence. In 12-d-old seedlings removal of one cotyledon doubled the CO2 fixation rate of the other, as observed 3 d after treatment. When the primary leaf was removed, the photosynthetic rate of the cotyledons was decreased by 33%. At this stage of growth elimination of the roots as a sink for assimilates by girdling the hypocotyl affected neither the photosynthetic rate nor the carbohydrate content of the cotyledons. By contrast, in 18-d-old seedlings removal of the first leaf brought about a 42% increase in the photosynthetic rate of the cotyledons. The simultaneous removal of the first leaf and one cotyledon doubled the rate of CO2 fixation of the remaining cotyledon. Girdling the hypocotyl lowered the photosynthetic rate of the cotyledons by 73%. In both 12- and 18-d-old seedlings a decrease or increase in the sink-source ratio was correlated with an increase or a decrease respectively in the carbohydrate content of the cotyledons. The stomatal resistance of the cotyledons was not affected by any of the treatments. The effect of sink-source manipulations on photosynthesis and on the level of carbohydrates present in the cotyledons was more evident in those seedlings growing under high light intensity (580 μE m-2 s-1), than in those exposed to 300 μE m-2 s-1 © 1985 Oxford University Press.

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