EFFECT OF TEMPERATURE ON BIOMASS ALLOCATION IN TOMATO (LYCOPERSICON-ESCULENTUM)

Temperature may influence dry matter partitioning between fruits and v egetative plant parts either directly or indirectly through its influe nce on development, flower and/or fruit abortion. The objective of the present work was to investigate whether there is any direct effect of temperature on dry matter partitioning between fruits and vegetative plant parts in tomato. A greenhouse experiment was conducted, with alt ernating 3-week periods of high (23 degrees C) and low (18 degrees C) temperature setpoint. Dry matter partitioning during these 3-week peri ods was determined from destructive plant harvests at two levels of fr uit pruning (3 and 7 fruits per truss). Indirect temperature effects o n dry matter partitioning were excluded by fruit pruning. On average, the fraction of dry matter distributed to the fruits during a 12-week period, starring with the flowering of the fifth truss (28 days after planting), was 0.53 (3 fruits per truss) and 0.70 (7 fruits per truss) . These ratios were also calculated for every 3-week period separately and did not depend on the average temperature (18-24 degrees C) durin g that period. It is concluded that dry matter distribution in tomato is not significantly affected by temperature directly, which means tha t the temperature effect (18-24 degrees C) on the generative sink stre ngth is not much different from the temperature effect on the vegetati ve sink strength.