Resumen de Effects of sodium molybdate foliar sprays on molybdenum concentration in the vegetative and reproductive structures and on yield components of Vitis vinifera cv. Merlot
Mardi Longbottom, Peter R. Dry, Margaret Sedgley
Background and Aims: Molybdenum deficiency(Mo‐deficiency) has been suggested to be the cause of poor yield of own‐rooted Merlot vines in Australia. The aims of these experiments were to quantify the effect of foliar molybdenum treatment (Mo‐treatment) on vine molybdenum status and to identify which components of yield are affected by Mo‐treatment.
Methods and Results: Experiments were conducted on own‐rooted Vitis vinifera cv. Merlot in South Australia in 2003–07. Vines were sprayed with two rates of sodium molybdate (0, 0.101 and 0.202 g/vine) in the spring. Vine molybdenum status was assessed at flowering and juice molybdenum concentration was measured at harvest. The effects of Mo‐treatment on vine growth and yield were also measured. Mo‐treatment significantly increased yield of molybdenum deficient vines, a function of improved fruitset. Mo‐treatment significantly increased the concentration of molybdenum in the petioles, shoot tips and inflorescences compared with the controls. Budburst was delayed on molybdenum‐treated vines in the spring following Mo‐treatment. The concentration of molybdenum in grape juice only increased in vines that had sufficient molybdenum.
Conclusions: Mo‐treatment increased vine molybdenum status; however, yield only increased on Mo‐deficient vines. The increase in yield was a function of improved fruitset.
Significance of the Study: This research demonstrates a significant positive relationship between vine molybdenum status and fruitset of own‐rooted Merlot vines.
