Interactions between changing climate conditions in a semi-closed greenhouse and plant development, fruit yield, and health-promoting plant compounds of tomatoes

Abstract Climate change will lead to an excessive change in climate conditions in greenhouses, particularly during the summer. Therefore, a new climate strategy for greenhouses was developed to avoid plant damages. In this context, interactions between changing microclimatic conditions depending on different climate strategies and plant growth, fruit yield as well as secondary plant compounds were investigated between 2008 and 2009. The results showed that a combined application of a high pressure fog system and CO 2 enrichment can be applied to decrease the inside temperature and to increase the levels of relative humidity and CO 2 concentrations at a high ambient temperature, accompanied by an increase in mean temperature. Such microclimate in the greenhouse were sufficient to accelerate plant growth, to increase dry matter in leaves, and to promote the formation of fruit set per truss in comparison to those grown under conventional climate conditions. Furthermore, the algorithm of the new climate strategy led to a maximum total yield increase by 20%, to a reduction of blossom-end rot in tomatoes and to a pronounced increase in fruit size during the spring experiments. The climate conditions caused by the new technology significantly promoted secondary metabolism, resulting in a maximum increase in contents of lycopene (by 49%), β-carotene (by 35%), and phenolic compounds (by 16%) as well as associated antioxidant activity in the water-insoluble (by 18.5%) and water-soluble (by 35.4%) fraction compared to the conventional treated plants. Therefore, the new climate strategy may be appropriate to increase the total yield and to improve the fruit quality as well as the health-promoting properties of tomatoes.