Timing of nitrogen application to macadamias. 3. Reproductive growth, yield and quality

Abstract

Depression of flowering in macadamias (Macadamia integrifolia Maiden and Betche) was associated with low nitrogen (N) status following 1 application of N (690 g N/tree.year) in summer of the first season and in control trees (monthly applications totalling 230 g N/tree.year) in the second and third seasons. Yield responses to N were observed only in the second and subsequent seasons. Yields of commercially acceptable nuts were higher, and small reject nuts lower, than nuts produced by control trees. Nut quality from control trees was as good as, and in many cases superior to fertilised trees receiving the higher rate of N in 1 application at various times through the year. Forward stepwise multiple regression analyses indicated the importance of time and extent of vegetative flushing, total annual tree growth and carbohydrate reserves stored in tree trunks on nut yield and quality. An appreciation of these factors can be used to guide management decisions for optimum production and quality of macadamias.