BMC Plant Biology最新文献

Background: Tartary buckwheat (Fagopyrum tataricum) is predominantly cultivated in arid and semi-arid mountainous regions. However, existing studies predominantly focus on describing the natural metabolic changes and the regulation of stress resistance during the germination of Tartary buckwheat. In contrast, research on the systematic influence of calcium ions on the germination physiology and metabolic networks of plants has yet to be reported. In this study, we elucidated the physiological mechanisms underlying calcium-mediated effects on Tartary buckwheat seed germination using six concentrations of CaCl₂ (0, 1, 2, 3, 4, and 5 g·L⁻¹).

Results: Exogenous calcium application exhibited a concentration-dependent effect on seed germination, characterized by low-dose promotion and high-dose inhibition. An appropriate calcium supply significantly promoted the accumulation of osmoregulatory substances, including total sugars, reducing sugars, and free amino acids, by enhancing the decomposition of starch and soluble proteins. Furthermore, it facilitated the accumulation of active compounds, such as total phenols, flavonoids, and γ-aminobutyric acid, and enhanced the activities of key enzymes including phenylalanine ammonia-lyase, glutamate decarboxylase, and α-amylase, thereby improving seed antioxidant capacity. Metabolomic analysis revealed that linoleic acid metabolism, D-amino acid metabolism, and phenylalanine metabolism are the core pathways involved in calcium-regulated seed germination. Furthermore, exogenous calcium systematically improved stress resistance and germination capacity by modulating the levels of key metabolites in these pathways, thereby influencing lipid remodeling, nitrogen metabolism, and secondary metabolite synthesis.

Conclusions: Exogenous calcium effectively promoted the germination of Tartary buckwheat seeds by mediating amino acid and lipid metabolism, thus regulating osmotic balance and the antioxidant defense system. The optimal treatment concentration identified was 3 g·L⁻¹ CaCl₂. This study elucidates the multiple mechanisms through which calcium regulates the germination of Tartary buckwheat seeds at both physiological and metabolic levels, providing a theoretical basis and practical guidance for the rational application of calcium fertilizers in Tartary buckwheat cultivation.

Soil salinization is a widespread environmental problem that enhancing plant salt tolerance and increasing plant biomass through agronomic measures is an urgent problem to be addressed. In this study, one-year-old 'Gui 109' mulberry (Morus spp.) seedlings, used for forage, were employed as experimental materials in a hydroponic system. The effects of different nitrogen application levels (0, 2, 6, 10, and 16 mmol·L^-1) on seedling growth, photosynthetic parameters, and physiological traits were investigated under varying salt stress levels (0, 0.1%, and 0.2% NaCl). The results showed that under salt stress, photosynthetic pigments, P_n, G_s, and T_r increased initially and then declined with increasing nitrogen supply, whereas C_i exhibited the opposite trend.With increasing salinity, these parameters showed a similar biphasic pattern, and inhibition was more pronounced at 0.2% NaCl during later stages.Under control conditions (CK),Na⁺ content decreased with increasing nitrogen at the early stage but displayed a decline-increase pattern later.Under salt stress, Na⁺ content displayed a decreasing-increasing pattern with rising nitrogen levels and increased progressively with higher salinity.The contents of K⁺, Ca²⁺, and Mg²⁺ in leaves and roots increased initially and then declined with increasing nitrogen supply and prolonged stress duration. Increasing salinity significantly reduced K⁺ and Ca²⁺ levels in both tissues.Correlation analysis revealed significant positive relationships among photosynthetic pigments. Net photosynthetic rate was positively correlated with stomatal conductance (0.91) and negatively correlated with intercellular CO₂ concentration (- 0.91). K⁺ was positively associated with photosynthetic performance, whereas Na⁺ showed negative associations. Overall, salt stress suppressed photosynthesis and disturbed ion uptake and transport. Moderate nitrogen improved salt tolerance by enhancing photosynthetic efficiency and ion regulation, whereas excessive nitrogen aggravated salt damage.