Abstract: We assessed water-biochar management mode in terms of tomato growth, yield and quality in solar greenhouse under different irrigation amounts based on 20 cm pan evaporation (E_p-20) in spring and autumn crop in Northeast China. We further tested the feasibility of using the 20cm pan to develop a drip irrigation scheduling. A split plot experiment was conducted, with irrigation amount as the main factor and biochar amount as the secondary factor. There were three irrigation levels of 0.6 E_p-20 (W₁), 0.8E_p-20 (W₂) and 1.0E_p-20 (W₃) and three biochar application levels of 0 (B₀), 20 t·hm^-2 (B₁) and 40 t·hm^-2 (B₂). The results showed that planting season affected the overall condition of the tomato plants. Application of high biochar amount(B₂) ameliorated the phenomenon of slow growth of tomato plant height in spring cropping and the poor physiological condition, yield and quality of tomato in autumn cropping, and increased the yield and quality of tomato in spring cropping and irrigation water use efficiency (IWUE) in both seasons. Increased irrigation and biochar application amount had positive effects on tomato growth and yield. Under the same biochar amount, when the irrigation amount exceeded the W₂ level, tomato yield did not change and tomato quality decreased with increasing irrigation amount. Under the condition of 20% reduction of irrigation in spring and autumn cropping compared to the control treatment W₃B₀, treatment W₂B₂ (the suitable water-biochar management) increased yield by 15.6% and 20.5%, IWUE by 44.5% and 50.7%, and taste acceptability by 8.2% and 4.5%, respectively. The daily 20cm pan evaporation in spring and autumn cropping was significantly correlated with both the reference crop evapotranspiration and crop water consumption. Our results showed that the W₂B₂ is a suitable year-round water-biochar management mode for solar greenhouse tomato. Our results can provide a reference for tomato cultivation in solar greenhouses in Northeast China.

Key words: pan, biochar, solar greenhouse, yield, quality.