Effect of balanced fertilization on red dragon fruit in Guangxi

In order to investigate yield limiting factors in red dragon fruit production and examine the optimal rates of K on the soils where red dragon fruit mainly grows, a two-year field experiment was conducted in Fangchenggang city, southern Guangxi. The experiment consisted of six treatments including the optimal treatment (OPT) as 411-188-675-150-1.3 kg N-P₂O5-K₂O-MgO-B/ha, OPT-N, OPT-P, OPT-K, OPT-1/2K, OPT-1/2K, OPT-Mg and OPT-B and replicated three times. Results showed that the yields of red dragon fruits were much higher in 2013 than in 2012 due to more favorable weather conditions. Similar to 2012, the OPT treatment significantly increased red dragon fruit yield compared to the N, P and K omission treatments. The yield reduction was 11133 kg/ha (-49.96%), 6200 kg/ha (-27.82%), 6400 kg/ha (-28.72%), 1850 kg/ha (-8.30%) and 950 kg/ha (-2.74%) for omitting N, P, K, Mg and B, respectively. Except for Mg, continued omission of the other four nutrients further expanded the yield gap between the OPT and the omission treatments. Unlike in 2012, cutting K fertilizer by half on the basis of the OPT decreased fruit yield by 1967 kg/ha (-8.83%) while increasing half rate of K fertilizer on the OPT basis further increased fruit yield by 550 kg/ha (2.47%), implying high demand of red dragon fruit for K fertilization. Through the two-year field experiments, the optimal fertilizer rates for red dragon fruit production in the region can be set as 420-230-650-140-1.3 kg N-P₂O5-K₂O-MgO-B/ha.