Objectives In order to cope with the elevating trend of environmental temperature and CO₂ concentration, we studied the effects of different irrigation amounts on the growth, yield, and quality of cherry tomatoes, and the key growth and photosynthetic factors related to the final yield and quality of fruits.

Method Using 'Fenmei 1' cherry tomato as the research subject, a three-factor randomized block experiment was conducted with two temperatures (T₁: ambient temperature, and T₂: ambient temperature + 2.3℃), two CO₂ concentrations (C₁: 400μmol/mol, and C₂: 800 μmol/mol), and three irrigation amounts (I₁: 75% Ep, I₂: 100% Ep, and I₃: 125% Ep), resulting in a total of 12 treatments. Sixteen indicators across five categories of growth, photosynthesis, yield, quality and irrigation water use efficiency of cherry tomato were determined. The regulatory effects of single factor and multi-factor interaction on different indicators were analyzed. The key indicators related to yield and quality were extracted using correlation analysis and path analysis.

Result I₁ treatments exhibited lower net photosynthetic rate (Pn) and total chlorophyll content during whole growing period. At the flowering-fruit setting stage, T₂C₂I₃ was recorded the maximum value, which was 51.5% higher than that of T₁C₁I₁. I₃ irrigation level promoted plant height and leaf area under T₂C₂ combination from flowering-fruit setting stag to fruiting stage, with the leaf dry matter accumulation of T₂C₂I₃ at fruiting stage was 81.7% higher than the minimum value T₂C₁I₁ at the same period. I₂ irrigation level promoted the accumulation of stem dry matter under T₂, with the maximum stem dry matter mass of 29.18 g in T₂C₂I₂ at the fruiting stage, which was 85.2% higher than the minimum value in T₂C₁I₁ during the same period. I₂ enhanced root growth across various environments, and T₁C₂I₂ was recorded the maximum root dry matter accumulation, exceeding the minimum observed in T₂C₁I₁ by 106.8% at the fruiting stage. Temperature and irrigation significantly affected all quality indexes. I₁ irrigation level increased the levels of total soluble solids, acidity, soluble protein, total soluble sugar and vitamin C under the combination of T₂C₁, with the total soluble sugar content showing the most significant increase of 61.1% compared to T₁C₁I₃. T₁C₂I₃ achieved the highest yield, which was 123.6% higher than the lowest T₂C₁I₁. I₂ irrigation level increased the irrigation water use efficiency under T₂ and C₁ environment conditions. Path analysis indicated that the net photosynthetic rate at seedling stage had the greatest contribution to yield, with a path coefficient of 0.539. Stem dry matter accumulation during the flowering-fruit setting stage and fruiting stage had the greatest contributions to lycopene and total soluble sugar content, with direct path coefficients of -0.695 and -0.660, respectively.

Conclusion In the experimental area, elevated temperature is detrimental to plant growth and dry matter accumulation from seedling to flowering-fruit setting stage of tomato, and it is also unfavorable for yield formation. However, elevated temperature xombined with mild drought could enhance the resistance and fruit quality of tomatoes. Under the future environmental trends of rising temperature and CO₂ concentration, increasing irrigation levels is a necessary means to fully utilize environmental factors and enhance the benefits of greenhouse-cultivated crops.