Variations in plant–microbe–soil C:N:P stoichiometry along a 900-year age gradient in Torreya grandis ‘Merrillii’ plantations in Southeast China

Researches on the ecological stoichiometry of forest vegetation at different growth stages under long-term human management activities and its driving factors will help to clarify how the limited nutrient resources are allocated at different growth stages of forests, providing a basis and suggestions for scientific cultivation of artificial forests. In subtropical China, the C:N:P stoichiometry of an ancient Torreya grandis ‘Merrillii’ community was measured in leaves, twigs, roots, soils, and soil microbes with age gradients of 0–50, 50–100, 100–300, 300–500, and more than 500 years. The results showed that the nutrient use varied with tree ages. The N and P concentrations in the leaves, twigs, and roots of T. grandis had the similar increasing trends with the increasing tree age, and the N concentrations in leaves in 0-50-year-old forests were significantly lower than those forests of other ages. Particularly, the N:P ratio of different organs was always below 10, reflecting limited N supply of plants. The soil C content increased with the increasing T. grandis forest ages while the soil microbe C showed a fluctuated trend. There was a higher correlation among the C, N and P contents and their ratios in leaves, twigs and roots of 0-50-year-old forests than that in soil microbes, but inversely at more than 500-year-old forests. The homeostasis analysis results showed that the roots and soil microbes are more indicative of soil nutrient availability. The results of redundancy analysis showed that acid phosphatase activity had the highest impact on soil microbes in 0–10 and 10–20 cm soil layers, confirming that the decomposition and transformation of P in soils is very active. Moreover, soil enzyme activity mediates the influence of soil microbes on soil N and P limitation. In summary, tree age can effect the plant–microbe–soil C:N:P stoichiometry of T. grandis forests. The growth of T. grandis is mainly restricted by N, and reasonable application of N fertilizer is needed to promote its growth

Photosynthesis, biomass and fine root growth dynamics of soybean in walnut-soybean agroforestry system

Abstract Background:Agroforestry system is regarded as a promising practice in sustainable agricultural management. However, the effects of long-term tree-based intercropping on crop remain poorly understood, especially in the Loess Plateau. In this study, the impacts of photosynthetic and respiration rate were determined by the portable photosynthesis system (Li-6400), and the effects of the root growth dynamics of soybean in walnut-soybean intercropping system were measured by soil auger and WinRHIZO root analysis system, in the Loess Plateau. Results:The results showed that soybean reached the highest net photosynthetic rate during flowering period, with the net photosynthetic rate of intercropped soybean, which was 20.40µmol·m-2·s-1, significantly higher than that of its monocropped counterpart. Soybean biomass reached the maximum during the pod-bearing period, with intercropped soybean biomass being 25.49g, significantly higher than that of its monocropped counterpart. The mean diameter and increased density of soybean fine roots reduced along with increased soil depth. Both the diameter (0.43mm) and increased density (930cm/dm3) of intercropped soybean fine roots were evidently higher than those of monocropped soybean(0.35mm, 780cm/dm3). With increasing cropping years, fine roots of intercropped soybean tended to be mainly distributed in soil at a depth between 0 and 20cm from the fifth year. Conclusion:Collectively, compared with soybean monoculture, walnut soybean agroforestry system is more conducive to soybean growth in the Loess Plateau.</jats:p

Analysis on the Influencing Factors of Green Technological Innovation Efficiency——Based on the Perspective of the Law Construction and Banking Efficiency

Based on provincial data from 2010 to 2016, this paper uses regression model to analyze the factors affecting the green technology innovation efficiency and discuss the impact from the perspective of law construction and banking efficiency. The result shows that the law construction significantly improves the green technology innovation efficiency while the banking efficiency has the opposite result. Therefore, it is necessary to optimize financial structure and strengthen the legal protection of technological innovation, and ultimately promote high-quality development

Photosynthesis, biomass and fine root growth dynamics of soybean in walnut-soybean agroforestry system

Abstract Abstract Background: Agroforestry system is regarded as a promising practice in sustainable agricultural management. However, the effects of long-term tree-based intercropping on crop remain poorly understood, especially in the Loess Plateau. In this study, the impacts of photosynthetic and respiration rate were determined by the portable photosynthesis system (Li-6400), and the effects of the root growth dynamics of soybean in walnut-soybean intercropping system were measured by soil auger and WinRHIZO root analysis system, in the Loess Plateau. Results: The results showed that soybean reached the highest net photosynthetic rate during flowering period, with the net photosynthetic rate of intercropped soybean, which was 20.40µmol·m-2·s-1, significantly higher than that of its monocropped counterpart. Soybean biomass reached the maximum during the pod-bearing period, with intercropped soybean biomass being 25.49g, significantly higher than that of its monocropped counterpart. The mean diameter and increased density of soybean fine roots reduced along with increased soil depth. Both the diameter (0.43mm) and increased density (930cm/dm3) of intercropped soybean fine roots were evidently higher than those of monocropped soybean(0.35mm, 780cm/dm3). With increasing cropping years, fine roots of intercropped soybean tended to be mainly distributed in soil at a depth between 0 and 20cm from the fifth year. Conclusion: Collectively, compared with soybean monoculture, walnut soybean agroforestry system is more conducive to soybean growth in the Loess Plateau.</jats:p

Exogenous Melatonin Mitigates Methyl Viologen-Triggered Oxidative Stress in Poplar Leaf

As a ubiquitous molecule, melatonin plays a crucial role in tolerance to multiple stresses in plants. In the present work, we report the role of exogenous melatonin in relieving oxidative stress induced by methyl viologen (MV) in poplar (Populus alba &#215; Populus glandulosa) leaf. Leaf discs pretreated with melatonin exhibited increased tolerance to MV-mediated oxidative stress. It was observed that melatonin pretreatment effectively reduced membrane damage and lipid oxidation as demonstrated by decreased relative electrolyte leakage and malonaldehyde content in poplar leaf discs. Exogenous melatonin also stimulated activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX), and enhanced accumulation of non-enzymatic antioxidants of AsA and GSH in leaf discs exposed to MV. In addition, pretreatment of melatonin prompted expression of genes for those antioxidant enzymes. Notably, exogenous melatonin increased expression of P5CS, a key gene for proline biosynthesis, under MV treatment. It was further observed that pretreatment with melatonin boosted activity of P5CS as well as accumulation of proline in leaf discs under MV-mediated oxidative stress. Collectively, this work provides evidence for the ameliorative effect of melatonin on MV-induced oxidative stress in poplar leaf

Sedoheptulose-1,7-Bisphosphatase is Involved in Methyl Jasmonate- and Dark-Induced Leaf Senescence in Tomato Plants

Leaf senescence represents the final stage of leaf development and is regulated by diverse internal and environmental factors. Jasmonates (JAs) have been demonstrated to induce leaf senescence in several species; however, the mechanisms of JA-induced leaf senescence remain largely unknown in tomato plants (Solanum lycopersicum). In the present study, we tested the hypothesis that sedoheptulose-1,7-bisphosphatase (SBPase), an enzyme functioning in the photosynthetic carbon fixation in the Calvin&ndash;Benson cycle, was involved in methyl jasmonate (MeJA)- and dark-induced leaf senescence in tomato plants. We found that MeJA and dark induced senescence in detached tomato leaves and concomitantly downregulated the expression of SlSBPASE and reduced SBPase activity. Furthermore, CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9)-mediated mutagenesis of SlSBPASE led to senescence-associated characteristics in slsbpase mutant plants, including loss of chlorophyll, repressed photosynthesis, increased membrane ion leakage, and enhanced transcript abundance of senescence-associated genes. Collectively, our data suggest that repression of SBPase by MeJA and dark treatment plays a role in JA- and dark-induced leaf senescence

Photosynthesis, biomass and fine root growth dynamics of soybean in walnut-soybean agroforestry system

Abstract Background:Agroforestry system is regarded as a promising practice in sustainable agricultural management. However, the effects of long-term tree-based intercropping on crop remain poorly understood, especially in the Loess Plateau. In this study, the impacts of photosynthetic and respiration rate were determined by the portable photosynthesis system (Li-6400), and the effects of the root growth dynamics of soybean in walnut-soybean intercropping system were measured by soil auger and WinRHIZO root analysis system, in the Loess Plateau. Results:The results showed that soybean reached the highest net photosynthetic rate during flowering period, with the net photosynthetic rate of intercropped soybean, which was 20.40µmol·m-2·s-1, significantly higher than that of its monocropped counterpart. Soybean biomass reached the maximum during the pod-bearing period, with intercropped soybean biomass being 25.49g, significantly higher than that of its monocropped counterpart. The mean diameter and increased density of soybean fine roots reduced along with increased soil depth. Both the diameter (0.43mm) and increased density (930cm/dm3) of intercropped soybean fine roots were evidently higher than those of monocropped soybean(0.35mm, 780cm/dm3). With increasing cropping years, fine roots of intercropped soybean tended to be mainly distributed in soil at a depth between 0 and 20cm from the fifth year. Conclusion:Collectively, compared with soybean monoculture, walnut soybean agroforestry system is more conducive to soybean growth in the Loess Plateau.</jats:p