Effects of autumn nitrogen nutrition and a winter restbreaking spray on the growth, development and chemical composition of young 'Golden Delicious' apple trees grown in sand culture
Omission of N during autumn on pot-grown 'Golden Delicious/Merton 793' apple trees resulted in accelerated leaf-drop and lower total N, soluble N, protein N, P and Ca, and higher starch, total sugars and K in the dormant terminal shoots in comparison with a full autumn N treatment. Omission of both autumn N and the artificial rest-breaking spray resulted in delayed bud-break and flowering but the effect of these two treatments was inter-dependent. Neither the autumn application of N alone nor the rest-breaking spray alone resulted in completely satisfactory bud-breaking and flowering. Omission of autumn N and/or the rest-breaking spray reduced flower number per tree. Omission of both factors resulted in very poor fruit-set while, where only one of these two factors was omitted, the fruit-set was not reduced. Fruit-set was strongly related to the time of flowering. Autumn N nutrition also showed a residual effect on growth and the leaf nutritional status the following season. © 1979.