Effects of light intensity, soil acidity, and nitrogen concentration on the vegetative growth of pitaya seedlings^©

INTRODUCTION
Pitaya (Hylocereus undatus) is a little-known tropical fruit in Japan. Pitaya fruit contains important nutrients to enhance human health, including dietary fiber, vitamins, minerals, and polyphenols (Mahattanatawee et al., 2006). The fruit also contains oligosaccharides known to improve the intestinal environment (Wichienchot, 2010). Red pitaya fruit contains betalains, pigments with antioxidant activity that are used as natural dyes and to remove active oxygen species (Wu et al., 2006; Tenore et al., 2012).
The pitaya flower opens at night and wilts the next morning. It resembles the queen of the night flower (Epiphyllum oxypetalum), which is approximately 25-30 cm in length. The queen of the night flower usually blooms 3-4 times a year, whereas the pitaya flower blooms 5-6 times a year, from spring to autumn.