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Open AccessArticle

Potassium and Magnesium Mediate the Light and CO2 Photosynthetic Responses of Grapevines

NSW Department of Primary Industries, Wagga Wagga, NSW 2678, Australia
National Wine and Grape Industry Centre, Charles Sturt University, Wagga Wagga, NSW 2678, Australia
Author to whom correspondence should be addressed.
Biology 2020, 9(7), 144;
Received: 14 June 2020 / Revised: 22 June 2020 / Accepted: 26 June 2020 / Published: 28 June 2020
(This article belongs to the Section Plant Science)
Potassium (K) and magnesium (Mg) deficiency are common stresses that can impact on grape yield and quality, but their effects on photosynthesis have received little attention. Understanding the diffusional and biochemical limitations to photosynthetic constraints will help to guide improvements in cultural practices. Accordingly, the photosynthetic response of Vitis vinifera cvs. Shiraz and Chardonnay to K or Mg deficiency was assessed under hydroponic conditions using miniature low-nutrient-reserve vines. Photosynthesis was at least partly reduced by a decline in stomatal conductance. Light and CO2-saturated photosynthesis, maximum rate of ribulose 1.5 bisphospate (RuBP) carboxylation (Vcmax) and maximum rate of electron transport (Jmax) all decreased under K and Mg deficiency. Likewise, chlorophyll fluorescence and electron transport were lower under both nutrient deficiencies while dark respiration increased. K deficiency drastically reduced shoot biomass in both cultivars, while root biomass was greatly reduced under both Mg and K deficiency. Taken together, these results indicate that the decrease in biomass was likely due to both stomatal and biochemical limitations in photosynthesis. Optimising photosynthesis through adequate nutrition will thus support increases in biomass with carry-on positive effects on crop yields. View Full-Text
Keywords: A-ci response curves; nutrient deficiency; photosynthesis; Vitis vinifera A-ci response curves; nutrient deficiency; photosynthesis; Vitis vinifera
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Rogiers, S.Y.; Greer, D.H.; Moroni, F.J.; Baby, T. Potassium and Magnesium Mediate the Light and CO2 Photosynthetic Responses of Grapevines. Biology 2020, 9, 144.

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