A study on Dragon fruit variety and effects of fertilizer on yield and quality of Dragon fruit (Hylocereus undatus) was conducted at Rajamangala University of Technology Suvarnabhumi Huntra Ayutthaya from October 2008 to October 2012. The soil type condition was a clayey type (59% clay) containing very low amount of organic matter (0.79%) low phosphorus (3 ppm) but very high potassium (230 ppm). There were 12 varieties of Dragon fruit collected from all over Thailand for growth study and yield trial. It was found that the variety from Rayong Province which originally introduced from Vietnam gave the maximum yield (4164.25 kg/rai/year). Application of chemical fertilizer at the rate of 0 300 600 and 900 g/trellis/year was carried out to study the effects of fertilizer on growth and yield of Dragon fruit. The results have shown that the application of chemical fertilizer at the rate of 900 and 600 g/trellis/year gave better growth more flowers and fruits per trellis which resulted in maximum yield; 4230.75 and 4185.50 kg/rai/year respectively. The fertilizer application resulted in decreasing the texture firmness and total soluble solids but increasing the vitamin C content.

The colors improvement; lightness (L*) redness (a*) and yellowness (b*) in red swordtail fish by betalain (BTL) extracted from dragon fruit peel were evaluated. The fish were feed by commercial dietary pellet which spray with BTL; 0 40 and 60 milligrams/kilogram. After 8 weeks the average of L* a* and b* values of every treatment were not statistical significant (p>0.05) those might be cause from spirulina sp. added in commercial feed. The treatments were feed by 40 and 60 milligram/kilogram showed higher tendency of average L* a* and b* than 0 milligram/kilogram. The growth rate of every treatment were not statistical significant (p>0.05) and the survival rate of BTL intake groups were higher than without BTL. So BTL were not growth inhibit substance. In the other hands BTL might be the natural immune stimulation substance.