CPPU promotes growth and invertase activity in seeded and seedless muskmelons during early growth stage

We compared the growth and invertase activity of pollinated melon (Cucumis melo L.) fruit and parthenocarpic fruit induced by CPPU [1-(2-chloro-4-pyri dyl)-3-phenylurea]. CPPU - treated fruit enlarged from anthesis until the 15th day after anthes is (DAA). However, the growth of parthenocarpic fruit was slower than that of pollinated fruit during the later growth stage. Non-pollinated flowers w ithout the CPPU treatment did not grow; they wilted within 7 DAA. Acid inve rtase (Ai) and neutral invertase (NI) activities in the ovary rapidly decre ased from 0 to 5 DAA, whereas, AI activity in the mesocarp of pollinated an d/or CPPU-treated fruit dramatically increased to 5 DRA, it declined as fru it matured. Al activity in CPPU-treated fruit was higher than that of polli nated fruit without the CPPU treatment during the early stage; but between 25 and 40 DAA, the activity in CPPU - treated non - pollinated fruit was lo wer than that in the pollinated ones. NI activity was lower than Al activit y in the mesocarp in all plots throughout fruit development. The seasonal p atterns in NI activity were similar to those of Al activity. There was a cl ose relationship between the growth rate and invertase activity in melon fr uit. CPPU noticeably stimulated those activities in mesocarp tissues at ant hesis and shortly thereafter.