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Pitaya is a new tropical and subtropical fruit trees, it sets fruit, flower, vegetable, health care as one and has high economic value. At present, the study of pitaya quality and physiological system are not many in China and abroad, especially, the study of pitaya fruit development and quality analysis have not been involved in the karst mountain area under specific ecological condition. In this study, pitaya (Hylocereus spp.) was used to be the test material to explore the change law of water content, soluble solids, titratable acid, pH, mineral elements and respiration rate of pitaya fruit and to analyze nutriment of pitaya flesh and flower. The main results are the following:1. During the growth and development of pitaya fruits, vertical and horizontal diameter of fruit growth experienced three stages that were respectively fast growth period, slow growth period, fast growth period at the beginning of ripening, the result indicated that the development of pitaya fruits presented doubles S curve.2. It took about 27-30 days from blossom to ripen for pitaya fruit, fruit weight has 2 growth peaks during growth development period. The fresh and dry weight development of pitaya fruits presented doubles S curve. Water and dry matter in flesh accounting for the largest proportion, followed by skin, squama at least in mature Qianglong No.1 fruit. Pericarp changed from green to light red, finally to faint red or mauve, soluble solids increased rapidly, acidity increased first and then decreased and water content increased when pitaya fruit became mature.3. Potassium content in pitaya fruit squama and flesh were at a fairly high level 3 days after flowering, and then intended to drop, potassium content in fruit pericarp was highest during fruit mature stage. Throughout the fruit development period, the potassium content was higher than other nutrient elements content during the whole fruit development was, calcium content was highest in pitaya flesh 3 days after flowering and decreased obviously with the fruit development. From the change law of 10 nutrients in the squama, pericarp and flesh, many nutrient elements contents were in the highest level, after that, with the rapid increase of young fruit, mineral elements gradually decreased. Until fruit maturation period, all kinds of mineral nutritions content tended to be stable.4. Respiratory rate increased rapidly and reached the peak during the period of pitaya early fruit growth and development. Subsequently, fruits respiratory rate had been decreasing, at harvest, fruit respiration rate decreased to the lowest point, pitaya fruit respiratory rate exhibits a change law of typical non-climacteric fruit during the ripening period of pitaya.5. Pitaya fruit has rich nutrition, and rich in sugars, organic acids, dietary fiber, especiallly dietary fiber and protein contents are separately 2.33% and 1.12%, and protein contents of pitaya with red flesh was 1.30%. Pitaya fruit contains 17 amino acids, including 8 kinds human necessary amino acids, and the amount of which covers 34.8% of total amino acids. Pitaya fruit contains more mineral nutrients, particularly potassium, phosphorus, magnesium, calcium-rich contents are rich. Mineral nutrients content of pitaya produced in Luodian conty located in Guizhou karst mountain area is higher than pitaya from Conghua, Guangdong.6. Pitaya flower has rich nutrition, and rich in sugars, organic acids, dietary fiber, protein and varied vitamin, dietary fiberand and protein contents were separately 17.4% and 15.0%, and protein content of filament reachs 16.8%. Pitaya flower contains 17 amino acids, including 8 kinds human necessary amino acids, and the amount of which covers 43.8% of total amino acids. Pitaya flower contains phosphorus, potassium, calcium, magnesium, zinc, iron and selenium et al mineral nutrients, of which potassium, magnesium, calcium, phosphorus contents are more abundant.
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