Physiological and morphological changes over the past 50 years in yield components in tomato

Abstract

Greenhouse tomato (Solanum lycopersicum) yield in The Netherlands has increased tremendously over the past 50 years. The effects of breeding during this period were investigated. Eight Dutch cultivars and one typical current Japanese cultivar that were released over the past 50 years were compared in a short-term experiment conducted from summer to fall in The Netherlands. Fresh fruit yield of the Dutch cultivars significantly increased ~0.9% per year with the year of release from 1950 to 2000. Dry weight fruit yield of the Dutch cultivars also increased with the year of release, whereas the fruit dry matter content was not correlated with the year of release. Total dry matter production of plants increased with the year of release, and the dry matter partitioning to fruit was not correlated with the year of release. An increase in dry matter production was caused not by an increase in fraction of intercepted light, but by light use efficiency based on correlations between each of them and the year of release. The light extinction coefficient in the plant canopy decreased, whereas leaf photosynthetic rate increased significantly with the year of release. Although fresh fruit yield of the Japanese cultivar was lower than that of the modern Dutch cultivars, fruit dry matter content of the Japanese cultivar was higher than that of the Dutch cultivars. An increase in yield over the past 50 years in Dutch tomato was caused by an increase in light use efficiency resulting from a decrease in light extinction coefficient (a morphological change) and an increase in leaf photosynthetic rate (a physiological change).