Translocation of 11C-labelled photosynthates to strawberry fruits depends on leaf transpiration during twilight

Abstract

Photosynthate translocation from leaves to fruits is an important determinant of crop yield and quality. In protected cultivation, environmental control based on photosynthate translocation is indicative for realising high-yield and high-quality production. There are, however, few studies on the environmental response of photosynthate translocation, especially during twilight. In greenhouses, these transition periods are characterised by a drastic change in relative humidity (RH). In this study, we focused on light intensity as a key environmental factor to steer translocation under high RH prevailing under twilight conditions. We fed 11CO2 to a leaf of strawberry plants (Fragaria × ananassa Duch.) and analysed real-time dynamics of 11C-labeled photosynthate translocation to individual fruits on an inflorescence of intact plants by using positron emission tomography (PET) under different light intensities (i.e., 50, 200 and 400 μmol m−2 s−1). No clear relationship was obtained between 11C-photosynthate translocation and light intensity since the results revealed that translocation rates into the fruits were highest under the light intensity of 200 μmol m−2 s−1 followed by those of 400 and 50 μmol m−2 s−1. However, there was a strong negative correlation between transpiration rate of the 11C-fed leaf and 11C-photosynthate translocation rate. These novel findings indicate that transpiration, which controls leaf moisture status, is one of the drivers for photosynthate translocation towards fruits during twilight conditions.