Regulation Of Nitrogen To Apple Fruit Development, Yield And Quality

The experiments including soil application N with thinned treatment, foliar application N with thinned, ring-barking treatment, and priming leaf treatment were did to study the effect of N on fruit development, yield and fruit quality using eight to ten-year-old apple trees (M.domestica Borkh.Cv.Red Fuji/ M.hupenensis Rhed) as materials in Taian, Qixia and Laixi et al. orchards from 1998 to 2000. The main results were as follows: 1.On heavily thinned trees, SS activity was independent of N and priming leaves treatments,the result show that the carbohydrate restriction of source to sink activity did not exist,N application did not stimulate fruit growth rates relative to those on nonfertilized trees,however N fertilization resulted in a longer fruit development period and increase the growth potential of individual fruit by 20.8% (fresh weight) and 14.1% (dry weight) vs. controls. In Unthinned trees ,SS activity was increased by Nfertilization but decreased by priming leaves treatment,so the carbohydrate restriction of source to sink activity existed, N fertilization increased the average single fruit weight both by extending the fruit development period and by increasing fruit growth rate, and the increasing rates were 28.2% (fresh weight) and 19.4 %(dry weight) compared to the unthinned nonfertilized controls. 2. N fertilization influenced hermone concentration and its change trends in flesh, particularly increased ZRs,ABA and IAA concentration in flesh cell enlargement period.But the GA3, ABA and IAA concentration peak values appearance time were later 1-2 weeks than nonfertilized controls. GA , ABA and IAA concentration peak values appearance time was slightly ahead of fruit RGR peak values appearance time. The results show that N regulated fruit development by influencing fruit hormone concentration.