Effects of supplemental lighting and fruit thinning on fruit yield and source-sink relations of greenhouse tomato plants

Abstract

The purposes of this study is to determine an optimal source sink relationship by prunning clusters to an appropriate size to maximize fruit yield of tomato plants grown under supplemental lighting (SL). An increase in SL from 50 to 150 μmol · m-2 · s-1 resulted in an increase in total fruit yield and percentage of marketable fruit. Large cluster size decreased percentage of marketable fruit. A SL of 150 μmol · m-2 · s-1 with fruit thinning prevented the reduction in marketable fruit yield. Using a SL of 150 μmol · m-2 · s-1 increased photosynthesis and sugars and starch centent in leaf. Fruit thinning caused an increase in glucose, fructose, and starch content in leaf but a reduction in photosynthetic rate. A large cluster size, representing a high photosynthate demand, decreased sugars and starch content and increased photosynthesis rate. The combination of a SL of 150 μmol · m-2 · s-1 with 3 fruit/cluster appears to be a better source sink equilibrium during periods of low natural light.