Potted vines: Exploring the management effect of leaf area to fruit weight ratios on yield and quality

Abstract

The concept of vine balance is attaining a functional equilibrium between the three essential grapevine sinks — fruit, shoots, and roots. This means that any manipulation of source-sink balance that alters competing sinks will influence the equilibrium of the plant. The leaf area to fruit weight ratio (LA:FW) is a key metric used for assessing balance between the vegetative and reproductive growth of the vine. This ratio indicates that the main source of carbohydrates supplied to the fruit derives from leaf photosynthesis. A leaf area of 0.8-1.5m² of leaf/kg of fruit is reported to be optimal in the field. An alternative measure is that to ripen a bunch a shoot requires 14 leaves. Thus, vines that are source limited (inadequate leaf area) or have a high yield and excessive sink demand, will potentially have inadequate carbohydrates to enable fruit to reach an optimum ripening. The outcome of this imbalance is grapes can be low in soluble solids concentration, lighter colour, and undeveloped flavours and aroma at harvest. Therefore, it is essential to define the right balance between the vegetative and productive relationship to increase yield as well as improving the biochemical composition of the grape, ultimately affecting the yield-quality seesaw.