Physiological integration of growth and photosynthesis of Zoysia japonica clonal ramets under nutrient heterogeneity

Abstract

This study was carried out to analyze the changes of growth and photosynthesis of clonal ramets under nutrient heterogeneity, where the connected and disconnected ramets were treated with different nutrient levels. The results showed that under the nutrient heterogeneity the parent ramets in middle or high nutrient levels improved leaf length, leaf width, root mass, leaf mass, net photosynthetic rate, stomatal conductance, transpiration rate and water use efficiency of the connected daughter ramets, with an increase of 16.0%, 8.3%, 24.4%, 58.1%, 30.3%, 54.0%, 9.2% and 21.9% in high nutrient level, respectively, but reduced the root/shoot and intercellular CO2 concentration of the connected daughter ramets, with a decreases of 21.6% and 31.5% in high nutrient level, respectively. In contrast, the daughter ramets in the middle or high nutrient level had no significant impacts on the growth and photosynthesis of the connected parent ramets. There was a physiological integration from the parent ramets to the daughter ramets. The larger the nutrient differences of ramets was, the stronger the intensity of physiological integration was. The daughter ramets were the unidirectional beneficiary from the physiological integration, as the daughter ramets benefited from the parent ramets but had no positive effects on the daughter ramets.