Quantification of phosphorus-uptake effect on table grape (Vitis vinifera L.) cvs. Early Sweet and Crimson physiology, growth, and productivity using a lysimeter system

Evaluation of phosphorus (P) level is vital for vineyard management; however, our current understanding of how P supply affects table grapes, particularly growth, productivity, and quality parameters, is limited. We investigated the influence of various P-application levels on two table grape cultivars: the early-bearing white 'Early Sweet' and the late-bearing red 'Crimson'. During two consecutive seasons, grapevines were grown in 500-L lysimeters with perlite as the growth medium and subjected to three P-fertigation treatments (1, 5 and 15 mg L−1 P). High P-utilization efficiency (>90 %) was achieved for 1 and 5 mg L−1 P. Levels of P application were reflected in the P levels of diagnostic leaves, with blade analysis providing more consistent results than petiole analysis. Increased P supply reduced sugar accumulation in developing fruit. Primary cluster number was reduced with increased P supply for 'Crimson' vines in 2022. Low P caused a reduction in SPAD in leaves toward the end of the summer, indicating the importance of P for chlorophyll stability. In addition, low levels of P led to reduced vegetative growth, as reflected in evapotranspiration and leaf area index in 'Early Sweet' and in the dry pruning weight of both cultivars. Precise P management in 'Early Sweet' and 'Crimson' may increase growth, yield, and fruit quality, and will enable better P-utilization efficiency, thereby reducing costs and environmental contamination.