Heteroblastic Foliage Affects the Accumulation of Non-Structural Carbohydrates and Biomass in Pinus massoniana (Lamb.) Seedlings

Abstract

Pines have heteroblastic foliage (primary and secondary needles) during seedling stage, but how heteroblastic foliage affects carbon storage and biomass accumulation, contributing to seedling quality, is unclear. We investigated the influences of heteroblastic foliage on photosynthetic physiological characteristics, non-structural carbohydrate (NSC) and biomass accumulation in current-year seedlings; the key factors determining biomass accumulation were mainly determined by principal component screening, Spearman correlation, and path analysis. The results indicated that (1) primary needles have high photosynthetic pigments (chlorophyll a and total chlorophyll), net photosynthetic rates (Pn), the potential maximum photochemical efficiency (Fv/Fm), and leaf instantaneous water use efficiency (WUEi), whereas higher non-photochemical quenching (NPQ) suggested that sudden light increases induce the initiation of quenching mechanism in primary needles; additionally, secondary needles had a lower transpiration rate (Tr), limiting stomata (Ls), and light saturation point. (2) Secondary needles promoted soluble sugar (fructose and glucose) increases in leaves compared to that of primary needles and increased the leaf biomass accumulation (from 47.06% to 54.30%), enhancing the overall ability of photosynthetic organs; additionally, secondary needles can enhance the proportion of starch storage in the roots, and NSC accumulation was significantly increasing in the seedling leaves and roots. (3) Photosynthetic pigments (carotenoids, chlorophyll a, and total chlorophyll) had direct positive effects on primary needle seedling (PNS) biomass and promoted biomass by indirectly increasing soluble sugar synthesis in the stems. The Pn was the main physiological factor determining PNS biomass accumulation. In addition, the WUEi, Ls, and NPQ had direct negative effects on PNS biomass accumulation, inhibiting photosynthesis to limit seedling growth. Considering the functional traits in heteroblastic foliage is necessary when assessing different leaf types of Pinus massoniana (Lamb.) seedlings, in particular those threats implicated in light, water, and temperature relations. Our results can be beneficial to guide the establishment of seedling management and afforestation measures.

Effects of thinning on the understory light environment of different stands and the photosynthetic performance and growth of the reforestation species Phoebe bournei

“…The Spearman correlation method was used to preliminarily analyze the correlations of all indicators. Path analysis was used to study the correlation structure between the independent variable X i (i = 1, 2,…, n) and the dependent variable Y (Silveira et al 2015;Wang et al 2021a) to distinguish the effects of X i on Y into direct and indirect effects after obtaining the optimal regression equation using stepwise regression analysis, and to judge the relative importance of the contributions of the respective variables to the dependent variable by determining the magnitude of the path coefficients (Fig. 2).…”

“…The direct effects of independent variables on dependent variables and the indirect effects of interactions between these were examined in detail using stepwise regression and path analyses to identify essential links between several independent and dependent variables to provide a reliable basis for statistical decision-making (Wang et al 2021a). Figure 7a and b show that CO, LAI, and R/FR in the light environment have a limiting effect on the A sat of P. bournei seedlings, and that CO is the main limiting factor with the strongest direct effect according to the order of determination coefficients.…”

Effects of Drought Stress on Non-Structural Carbohydrates in Different Organs of Cunninghamia lanceolata

“…Drought stress affects the balance in carbon supply through photosynthesis and carbon utilization for plant metabolic respiration [9,10]. Under drought stress, plants regulate the metabolic activities related to carbon assimilation through different forms of NSCs [11]. NSCs are composed of soluble sugars (such as glucose, fructose, and sucrose) and starch.…”