FRUIT-GROWTH OF CUCUMBER IN RELATION TO ASSIMILATE SUPPLY AND SINK ACTIVITY

Assimilate distribution in C. sativus cv. Farbio was studied during 36 days after emergence of the inflorescence in the 5th axil. The interaction between negetative growth and reproductive development was examined. Daily net photosynthesis and the related assimilate supply were calculated by a simulation model. The actual dry matter accretion of vegetative and reproductive organs was derived from non-destructive measurements of organ dimensions and subsequent conversion to dry matter by statistical relations. Integrated over the total period of investigation, dry matter accretion derived either from the calculated assimilate supply or from actual measurements agreed well. A significant discrepancy appeared in the dynamic resolution where apparent periods of assimilate surplus were followed by periods of apparent shortage of assimilates. The regulation of temporary storage and subsequent remobilization of assimilates was studied in relation to source-sink interactions. A hypothesis was formulated that relates the dynamics of fruit growth to assimilate supply and the sink activity of individual fruits.