Validation study for balanced fertilizers on red dragon fruit

This field experiment was established in 2011 to validate the fertilizer rates tested for red dragon fruit, a perennial crop for Guangxi. The experiment consisted of seven treatments including the pre-set optimal treatment (OPT) of 414-250-660-140 kg N-P₂O₅-K₂O-MgO/ha, treatments individually omitting N, P, K, Mg, and treatment providing additional N or K. The N source was urea (46% N), single superphosphate was used for P (12% P₂O₅), KCl for K (60% K₂O), and MgSO₄ for Mg and S. The N, P and K sources were split three times between mid-April, mid-May and mid-August at proportions of 20%-50%-30% for N, 33%-67%-0% for P, and 25%-50%-25% for K. MgSO₄ was side-dressed once in mid-April.

Dragon fruit yields in 2014 were the highest since the trial began. The treatment effects on yield were similar to those in the past. The OPT treatment significantly increased fruit yield compared to the N, P and K omission treatments. The yield reduction was 8,650 kg/ha (-32%), 3,630 kg/ha (-14%), 4,480 kg/ha (-17%), and 1,670 kg/ha (-6.3%) for omitting N, P, K, and Mg, respectively. The OPT treatment produced the highest contents of titratable acids, soluble sugar, crude protein and vitamin C. Omitting Mg resulted in the lowest contents of soluble sugar, while omitting N minimized crude protein and vitamin C in the fruit. This implies that high yield and quality of dragon fruit can be achieved through nutrient management. Omission or inadequate application of any nutrient will reduce yield and quality.

This project has successfully defined nutrient management practices for local growers of high yielding and high quality red dragon fruit in Guangxi.