FRUIT-GROWTH AND BIOMASS ALLOCATION TO THE FRUITS IN CUCUMBER .2. EFFECT OF IRRADIANCE

Cucumber plants were grown at three different irradiances in a glassho use for a short (4 day) and an extended period (62 day). The biomass a llocation to the fruits increased with increasing irradiance when plan ts were grown over an extended period (62 day) at different irradiance s. In the short-term (4 day) the allocation to the fruits did not incr ease with increasing irradiance. The positive long-term effect of high irradiance on the biomass distribution to the fruits could primarily be ascribed to an increase in the number of fruits growing at the same time on the plant. The growth rate of individual fruits increased wit h increasing irradiance resulting in a shorter growing period from ant hesis until harvest of a fruit. The dry-matter percentage of both the fruits and the vegetative plant parts increased with increasing irradi ance.