Growth, Phenotypic Plasticity and Fruit Quality in Tomato: A Study under High Temperature and Elevated CO₂

We assessed the emergence, growth, phenotypic plasticity and quality of both landrace and commercial tomato fruits under conditions of elevated temperature and increased CO2 concentrations [CO2]. Four growth chambers were used in which temperature and [CO2] differed: LTLC (30 degrees C, 400 mu mol CO2 mol(-1)), LTHC (30 degrees C, 1200 mu mol CO2 mol(-1)), HTLC (40 degrees C, 400 mu mol CO2 mol(-1)) and HTHC (40 degrees C, 1200 mu mol CO2 mol(-1)). The acronyms indicate the following: LT, low temperature; HT, high temperature; LC, low [CO2]; and HC, high [CO2]. Elevated temperatures significantly affected emergence in both genotypes, with the rate decreasing below 35% at HT compared to over 95% at LT. At HT, seedlings died before producing true leaves. This increase in temperature negatively affected plant growth, though HC produced some compensatory growth promotion. Regarding HT and CO2 interactions, HC failed to counteract the negative impacts of HT. The commercial variety showed a higher relative distance plasticity index (RDPI) under HT, whereas the landrace showed greater plasticity in plant height under HC. The largest fruit sizes were observed at LT, whereas no fruits were found at HTLC. Elevated temperature at HC resulted in enhanced total phenol content and increased antioxidant activity in the fruits