Abstract: The objective of this study was to investigate the advantages of applying organic fertilizer and intercropping on the planting of red pitaya (Hylocereus costaricensis cv. ‘Tainong No. 2’). A field experiment was carried out to examine the effects of organic fertilizer application rate (F₀: 0 t·hm^-2 and F₂₀: 20 t·hm^-2) and intercropping method \[MP: monoculture pitaya, IP: pitaya intercropping peanut (Arachis hypogaea) and IS: pitaya intercropping soybean (Glycine max)\] on soil microbial abundance, soil microbial biomass and soil enzyme activity, as well as the yield and quality in red pitaya orchard in a dry-hot region. The relationship between the yield and quality of red pitaya and soil microbial characteristics were also analyzed. The results showed that compared with F₀ treatment, F₂₀ treatment significantly increased the abundance of soil bacteria, fungi, actinomycetes and microbial biomass carbon, nitrogen and phosphorus, enhanced the activities of soil invertase, urease, acid phosphatase and catalase, and improved the yield and quality of red pitaya. Compared with MP treatment, IP and IS treatment significantly increased soil microbial abundance, microbial biomass nitrogen and the activities of invertase and urease under F₀ and F₂₀ conditions; while IP and IS treatments significantly increased soil microbial biomass carbon, phosphorus and acid phosphatase activity only under F₂₀ condition. Intercropping significantly increased the fruit yield of red pitaya. IP and IS treatment increased yield by 48.48% and 42.20% under F₀ condition, and increased by 25.37% and 29.82% under F₂₀ condition, respectively, when compared with MP treatment. IP and IS treatments significantly increased soluble sugar and vitamin C content with F₀ conditions, but significantly increased vitamin C, soluble solids and protein content with F₂₀ conditions. Yield and quality of red pitaya were significantly positively correlated with soil microbial abundance, soil microbial biomass, and soil enzyme activity. The correlation between soluble sugar content and soil catalase activity was not significant. Therefore, the application of organic fertilizer and intercropping peanut or soybean can enhance soil microbial activity, thus improving the yield and quality of red pitaya in dry-hot region.

Key words: red pitaya, intercropping, organic fertilizer, soil microorganisms, soil enzyme activity, yield