|Authors: ||S. Muchjajib, U. Muchjajib, M. Jumee|
|Keywords: ||'Thongsam', seedless fruit, fruit fly, red colour|
Java apple (Syzygium samarangense (Blum) Merrill & Perry) is a commercial fruit in Thailand.
A recently-developed cultivar 'Thongsamsee' produces a desirable seedless bell-shaped red fruit with a less astringent taste relative to a previously-popularized cultivar 'Thabthimchan'. A study conducted from October 2011 to May 2013 in the central region of Thailand examined the effects of applications of plant growth hormones GA and NAA and fruit wrapping on the yield and quality of java apple 'Thongsamsee'. The plant growth hormones GA or NAA were applied as separate independent treatments at the rates of 2,500, 5,000, 10,000 and 15,000 mg L-1 by dipping the developing flowers at the stage of full bloom immediately after stamen abscission.
GA applied at the concentration of 2,500 mg L-1 produced the longest fruits (6.12×9.14 cm) and yielded 18.23 t ha-1, whereas NAA applied at 5,000 mg L-1 produced the broadest fruits (6.60×7.82 cm) and yielded 16.79 t ha-1; the nil application control treatment produced smaller fruits (5.40×8.06 cm) and a lower fruit yield of 14.81 t ha-1. GA applied at concentrations of 2,500 and 5,000 mg L-1 and NAA applied at the concentration of 5,000 mg L-1 increased fruit firmness and soluble solids content, but did not alter vitamin C content.
At the maximum application rate of 15,000 mg L-1, both GA and NAA caused abnormal growth and development of fruit.
To minimize damage by fruit fly (Dacus dorsalis), fruit wrapping is recommended at the stage of stamen abscission.
The intensity of the red fruit coloration of 'Thongsamsee' was influenced by the application of GA at 2,500 and 5,000 mg L-1 at the ambient temperature of the cool season.
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