Influence of temperature and salinity on tomato quality of a high value commercial cultivar

The combination of mild climate and soil salinity are the main causes of the exceptional fruit quality of some “flavour varieties” such as the hybrids of the Raf tomato. If conditions during fruit growth, mainly thermal and osmotic, are not adequate, the consumer does not always gets an acceptable fruit quality. The present work was conducted to study the effect of pre-harvest factors such as temperature and salinity on the quality of a high commercial value tomato cultivar. The experiment was conducted in a 12 m2 growth chamber, equipped with a control system for temperature, humidity and pure CO2 injection. Hybrid Raf tomato 'Dumas' grafted on Lycopersicon esculentum Mill. 'Arbiore' and grown in perlite substrate were exposed to four water salinity levels (2.5, 5.5, 8.0 and 12.0 dS m-1) and four day/night temperature regimes (20/14°C; 24/14°C; 28/14°C; 30/14°C). Salinity significantly increased soluble solid content (SSC) and titratable acidity (TA), but in contrast, the effect on pH was less responsive. Fruit firmness was strongly affected by salinity and adopted an inverse relationship from 24°C. Temperature affected significantly fruit quality at 28°C, quality parameters were reduced, except TA, which showed the highest values. Statistical analysis indicates an interaction between salinity and temperature, so that the reduction of quality parameters ​​caused by the temperature was less sensitive in the higher salinity treatments. The period of fruit development (PFD) was not affected by salinity in contrast, high temperature significantly reduced it. A strong direct relationship between PFD and the firmness was also observed. No differences in fruit quality parameters as affected by the different position of the trusses were observed. This study provides useful information to adjust climate control and fertigation set-points values in the cultivation of high value commercial tomato production.