Comparison of Four Methods Calculating the Seasonal Pattern of Plant Growth Efficiency of a Kiwifruit Berry

Four methods of determining the substrate requirements for synthesis of a kiwifruit [Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson var. deliciosa cv. Hayward] berry were compared using data derived from common kiwifruit berry samples collected from anthesis to fruit maturity. The four methods were based on fruit proximal analysis, elemental analysis, heats of combustion, or tissue carbon content. All methods gave similar patterns of seasonal costs and values of final cost to the plant (mean 1.21 g glucose g−1 season−1) but there was less agreement for growth respiration (mean 0.147 g glucose g−1 season−1). This is the first time that a continuous record of growth cost over the course of development has been presented, and the trends in seasonal cost reflect the uptake into and synthesis of the different biochemical constituents in the fruit. The differences between the results of each method reflect the underlying assumptions used in their development. It appears from this work that the method of McDermitt and Loomis (1981), utilizing elemental analyses, is most preferred.