Photosynthetic Acclimation and Growth Responses to Elevated CO₂ Associate with Leaf Nitrogen and Phosphorus Concentrations in Mulberry (<i>Morus multicaulis</i> Perr.)

• Main Authors: Songmei Shi, Xiao Xu, Xingshui Dong, Chenyang Xu, Yuling Qiu, Xinhua He
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Forests
• Subjects: biomass; chlorophyll; NPK uptake; photosynthesis; stomatal conductance; transpiration rate
• Online Access: https://www.mdpi.com/1999-4907/12/6/660

Mulberry (<i>Morus</i> spp.) is a multipurpose tree that is worldwide planted because of its economic importance. This study was to investigate the likely consequences of anticipated future elevated CO₂ (eCO₂) on growth, physiology and nutrient uptake of nitrogen (N), phosphorus (P) and potassium (K) in two most widely cultivated mulberry (<i>Morus multicaulis</i> Perr.) varieties, QiangSang-1 and NongSang-14, in southwest China. A pot experiment was conducted in environmentally auto-controlled growth chambers under ambient CO₂ (ACO₂, 410/460 ppm, daytime/nighttime) and eCO₂ (710/760 ppm). eCO₂ significantly increased plant height, stem diameter, leaf numbers and biomass production, and decreased chlorophyll concentrations, net photosynthetic rate, stomatal conductance and transpiration rate of these two mulberry varieties. Under eCO₂ leaf N and P, and root N, P and K concentrations in both mulberry varieties decreased, while plant total P and K uptake in both varieties were enhanced, and an increased total N uptake in NongSang-4, but not in QiangSang-1. Nutrient dilution and transpiration rate were the main factors driving the reduction of leaf N and P, whereas changes in plant N and P demand had substantial impacts on photosynthetic inhibition. Our results can provide effective nutrient management strategies for a sustainable mulberry production under global atmosphere CO₂ rising scenarios.