|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1996 : ¥200,000 (Direct Cost : ¥200,000)
Fiscal Year 1995 : ¥1,900,000 (Direct Cost : ¥1,900,000)
Apple fruits (cv. Jonathan) of -N plot (-N) receiving no nitrogen application from 1972 and of +N plot (+N) receiving 2kg N/tree in April of every year were investigated for flavonoid metabolism in apple skin. At harvest time, coloration rate of -N fruit was better than that of +N fruit. As flavonoid compounds in apple skin, anthocyanin (AN), leucoanthocyanin (LA) and quercetin glycosides (QG) were determined. The concentrations of total flavonoid compounds in fruit skin colored more than 90% were 383 nmol/cm^2 skin in -N fruit and 340 nmol/cm^2 skin in +N fruit. The ratios of each compound to total flavonoid was as follow ; AN 33%, LA 13% and QG 54% in -N fruit and AN 23% , LA 12% and QG 65% in +N fruit. These results suggest that heavy application of nitrogen inhibits the biosynthesis of AN and stimulates the biosynthesis of QG.
To clarify the cause of this phenomenon, fruit was cohered with glass filter paper absorbing treatment solution, then lapped with polyethylene film and incubated for 12hr at 25ﾟC.After removing glass filter paper, the fruits were incubated under continuous light (15 klux) for 72hr at 15ﾟC.Ammonium sulfate, asparagine (Asn) and polyamines were used as treatment solutions. One mM solution of these compounds inhibited AN development in apple skin. Phenylalanine (Phe), dihydroquercetin (DQ) and t-cinnamic acid (tC) as precursors of AN and QG biosynthesis were tested. Phe stimulated AN development in -N fruit, but it did not stimulate AN development in +N fruit. DQ and tC stimulated AN development in +N fruit. But these compounds had no effect to AN development in -N fruit.The inhibitory effect of Asn on AN development was alleviated by addition of DQ and tC.