Response of the root morphological structure of Fokienia hodginsii seedlings to competition from neighboring plants in a heterogeneous nutrient environment

IntroductionCritical changes often occur in Fokienia hodginsii seedlings during the process of growth owing to differences in the surrounding environment. The most common differences are heterogeneous nutrient environments and competition from neighboring plants.MethodsIn this study, we selected one-year-old, high-quality Fokienia hodginsii seedlings as experimental materials. Three planting patterns were established to simulate different competitive treatments, and seedlings were also exposed to three heterogeneous nutrient environments and a homogeneous nutrient environment (control) to determine their effect on the root morphology and structure of F. hodginsii seedlings.ResultsHeterogeneous nutrient environments, compared with a homogeneous environment, significantly increased the dry matter accumulation and root morphology indexes of the root system of F. hodginsii, which proliferated in nutrient-rich patches, and the P heterogeneous environment had the most significant enhancement effect, with dry matter accumulation 70.2%, 7.0%, and 27.0% higher than that in homogeneous and N and K heterogeneous environments, respectively. Homogeneous environments significantly increased the specific root length and root area of the root system; the dry matter mass and morphological structure of the root system of F. hodginsii with a heterospecific neighbor were higher than those under conspecific neighbor and single-plant treatments, and the root area of the root system under the conspecific neighbor treatment was higher than that under the heterospecific neighbor treatment, by 20% and 23%, respectively. Moreover, the root system under heterospecific neighbor treatment had high sensitivity; the heterogeneous nutrient environment increased the mean diameter of the fine roots of the seedlings of F. hodginsii and the diameter of the vascular bundle, and the effect was most significant in the P heterogeneous environment, exceeding that in the N and K heterogeneous environments. The effect was most significant in the P heterogeneous environment, which increased fine root diameter by 20.5% and 10.3%, respectively, compared with the homogeneous environment; in contrast, the fine root vascular ratio was highest in the homogeneous environment, and most of the indicators of the fine root anatomical structure in the nutrient-rich patches were of greater values than those in the nutrient-poor patches in the different heterogeneous environments; competition promoted most of the indicators of the fine root anatomical structure of F. hodginsii seedlings. According a principal component analysis (PCA), the N, Pm and K heterogeneous environments with heterospecific neighbors and the P heterogeneous environment with a conspecific neighbor had higher evaluation in the calculation of eigenvalues of the PCA.DiscussionThe root dry matter accumulation, root morphology, and anatomical structure of F. hodginsii seedlings in the heterogeneous nutrient environment were more developed than those in the homogeneous nutrient environment. The effect of the P heterogeneous environment was the most significant. The heterospecific neighbor treatment was more conducive to the expansion and development of root morphology of F. hodginsii seedlings than were the conspecific neighbor and single-plant treatments

Spatial-Temporal Evolution and Convergence Characteristics of Agricultural Eco-Efficiency in China from a Low-Carbon Perspective

While agriculture plays an essential role in food security, it is also one of the largest emitters of carbon emissions. China’s carbon neutrality and carbon peaking goals mean that China’s agriculture is also going through a low-carbon transition. To analyze the spatiotemporal heterogeneity and convergence of China’s agricultural eco-efficiency (AEE), this study used a combined super-efficient slacks-based measure (SBM), global Malmquist–Luenberger index (GML), kernel density estimation, Moran index, and convergence model on panel data from 2005 to 2020 and from 31 Chinese provinces. An innovative eco-efficiency index evaluation system was constructed from a low-carbon perspective that integrated agricultural carbon sinks and carbon emissions. The results revealed that the average AEE movement was U-shaped, but there were significant differences across regions and periods. The AEE demonstrated a gradual decreasing pattern of “northeast > eastern > western > central”, a declining trend during 2005–2010 and increasing trends during 2011–2020. The main reason for AEE growth was technological progress; however, technical efficiency only played a role in several provinces. The AEE in Chinese provinces was also found to have spatial autocorrelation characteristics dominated by high-high, low-low, and high-low clustering. A “catching-up effect” existed in the lagging AEE regions. Therefore, it is recommended to promote the integration of regional strategies and low-carbon development, build a low-carbon technology support system, and construct a national agricultural carbon trading center to facilitate agricultural low-carbon transformation

Spatial-Temporal Evolution and Convergence Characteristics of Agricultural Eco-Efficiency in China from a Low-Carbon Perspective

While agriculture plays an essential role in food security, it is also one of the largest emitters of carbon emissions. China’s carbon neutrality and carbon peaking goals mean that China’s agriculture is also going through a low-carbon transition. To analyze the spatiotemporal heterogeneity and convergence of China’s agricultural eco-efficiency (AEE), this study used a combined super-efficient slacks-based measure (SBM), global Malmquist–Luenberger index (GML), kernel density estimation, Moran index, and convergence model on panel data from 2005 to 2020 and from 31 Chinese provinces. An innovative eco-efficiency index evaluation system was constructed from a low-carbon perspective that integrated agricultural carbon sinks and carbon emissions. The results revealed that the average AEE movement was U-shaped, but there were significant differences across regions and periods. The AEE demonstrated a gradual decreasing pattern of “northeast > eastern > western > central”, a declining trend during 2005–2010 and increasing trends during 2011–2020. The main reason for AEE growth was technological progress; however, technical efficiency only played a role in several provinces. The AEE in Chinese provinces was also found to have spatial autocorrelation characteristics dominated by high-high, low-low, and high-low clustering. A “catching-up effect” existed in the lagging AEE regions. Therefore, it is recommended to promote the integration of regional strategies and low-carbon development, build a low-carbon technology support system, and construct a national agricultural carbon trading center to facilitate agricultural low-carbon transformation

Complete chloroplast genome sequence of Ampelocalamus scandens (Arundinarodae)

Ampelocalamus scandens is native to Guizhou Province, China, and grows at an altitude of 260–320 m. It can be used as a raw material for weaving and papermaking. In the current study, the complete chloroplast (cp) genome of A. scandens was sequenced and is reported for the first time. The complete cp sequence was 139,504 bp, include large single-copy (LSC), small single-copy (SSC), and a pair of invert repeats (IR) region of 83,103 bp, 12,813 bp, and 21,793 bp, respectively. Besides, the plastid genome comprised a total of 132 genes, including protein-coding, tRNA, and rRNA genes as 85, 39, and 8 genes, respectively. Phylogenetic analysis based on 28 cp genomes reveals that A. scandens is closely associated with Ampelocalamus melicoideus in Arundinarodae

Lower Light Intensities Increase Shoot Germination with Improved Leaf Biosynthesis in Ma Bamboo (<i>Dendrocalamus latiflorus</i> Munro)

Ma bamboo (Dendrocalamus latiflorus Munro) is a major bamboo species cultivated in southern China with high economic, ecological, and social value. However, highly dense forests and reasonable structures in bamboo forests have unclear and adverse effects on light transmittance and forest productivity that are not adequately understood. Here, we investigated varied light-intensity treatments during different phases of shoot emergence and development on Ma bamboo shoots. The amount of total chlorophyll, carotenoids, gas exchange indicators, and biosynthetic products were also compared to explore the response mechanism of shoot germination on downstream biochemical pathways. We found that compared to the L0 treatment (full sunlight), the number of germinated bamboo shoots under the L1 treatment (40% light) increased significantly by 44.07% and 101.32% in the shooting initial-phase and metaphase, respectively (p n) during the shooting initial-phase and metaphase was the highest in the L1 treatment, while the L4 (10% light) and L0 treatments inhibited chlorophyll synthesis. Further, the accumulation of leaf carbon (C) and nitrogen (N) was higher in the L1 treatment than in other treatments. Ma bamboo showed rich carbohydrate contents under L0 and L1 treatments in the shooting initial-phase and metaphase. Principal component analysis (PCA) also revealed that the L1 treatment positively correlated with bamboo shoot germination and biochemical activity during the shooting periods. Ultimately, our data suggest that the L1 treatment is the most optimal for promoting bamboo shoot germination, providing a scientific basis for cultivating shoot-used bamboo forests in southern China

Effects of Different Heterogeneous Nutrient Environments on the Growth and Activities of Enzymes in the Roots of <i>Fokienia hodginsii</i> Families

Currently, research on the F. hodginsii asexual lineage primarily focuses on the screening of growth traits and the control of single fertilizer applications. The effects of the heterogeneity of soil nutrients on root growth and activity have not been studied in detail. Therefore, we propose forest management measures to improve the foraging ability of forest trees in conjunction with stand productivity. In this experiment, annual containerized seedlings of 10 free-pollinated F. hodginsii lines from a primary asexual seed orchard were used as test subjects, and three heterogeneous nutrient environments of nitrogen (N), phosphorus (P), and potassium (K) were constructed. In contrast, homogeneous nutrient environments were used as the control to carry out potting experiments, to study the growth of F. hodginsii lines and the differences in the activities of root enzymes under the three heterogeneous nutrient environments, and to carry out the comprehensive evaluation using the principal component and cluster analysis method. The results were as follows: (1) The seedling height of F. hodginsii family lines under a homogeneous nutrient environment was significantly higher than that of all heterogeneous nutrient environments; the diameter of the ground was the highest under N heterogeneous nutrient environment and significantly higher than that of all the other nutrient environments; the biomass of the root system was the highest under P heterogeneous nutrient environment, which was significantly higher than that of homogeneous nutrient environment and K heterogeneous nutrient environment. The catalase (CAT) activity of F. hodginsii roots was higher than that of homogeneous nutrients in all heterogeneous nutrient environments but not significant, and the superoxide dismutase (SOD) activity was slightly higher than that of K heterogeneous and homogeneous nutrient environments in N and P heterogeneous nutrient environments. SOD activity was slightly higher than that of K heterogeneous and homogeneous nutrient environments under N, and P. peroxidase (POD) activity in the F. hodginsii root system was the highest under the P heterogeneous nutrient environment, which was significantly higher than that of the other nutrient environments. Unlike the activities of the enzymes, the content of malondialdehyde (MDA) in the roots of F. hodginsii was higher in the heterogeneous environment than in all the other nutrient environments. (2) Under N and P heterogeneous nutrient environments, lines 552 and 590 had higher seedling height, ground diameter, and root enzyme activity, while root biomass was highest in line 544; and under K heterogeneous nutrient environments, line 591 had higher seedling height, ground diameter, and root enzyme activity while root biomass was highest in line 551. In contrast to the patterns of seedling height, accumulation of root biomass and activities of root enzymes, family No. 590 had the highest ground diameter of all the F. hodginsii families under the heterogeneous nutrient environments. Family No. 547 had the highest MDA content. In conclusion, it can be seen that N heterogeneous and homogeneous nutrient environments can significantly increase the seedling height and diameter of F. hodginsii compared with P and K heterogeneous nutrient environments, and N and P heterogeneous nutrient environments can also increase the root biomass, root enzyme activities and significantly reduce the MDA content of F. hodginsii. According to the principal component analysis and cluster analysis, it can be seen that among the 10 F. hodginsii family lines, family lines 590 and 552 have higher evaluation in growth, root biomass accumulation, and enzyme activity

Complete chloroplast genome of Morinda parvifolia (Rubiaceae), a traditional medicinal plant in China

Morinda parvifolia is a traditional medicinal plant of the family Rubiaceae. In the current study, the complete chloroplast genome of M. parvifolia was sequenced and reported for the first time. The genome is 153,069 bp in total length, containing two inverted repeats (IR) regions of 25822 bp which were separated by a large single copy (LSC) region of 83813 bp and a small single copy (SSC) region of 17612 bp. A total of 131 gene species were annotated, including 86 protein-coding genes,37 tRNA genes, and 8 rRNA genes. The overall GC content of the genome is 38.07%. The phylogenetic analysis based on the complete chloroplast genome reveals that M. parvifolia is closely related to Morinda officinalis. This study enriches the genetic information of M. parvifolia as well as for the phylogenetic studies for Rubiaceae

Complete chloroplast genome sequence of Bambusa subtruncata (Bambusodae)

Bambusa subtruncata is found in Xinyi county, Maoming city, Guangdong province, China. In the current study, we sequenced the complete chloroplast genome of B. subtruncata and reported for the first time. The genome was 139,444 bp in total length, including a large single-copy (LSC) region of 82,956 bp, a small single-copy (SSC) region of 12,897 bp, and a pair of invert repeats (IR) regions of 21,798 bp. Plastid genome comprised of 127 genes in total; 82 protein-coding genes, 37 tRNA genes, and eight rRNA genes. Phylogenetic analysis based on 25 chloroplast genomes indicates that B. subtruncata is closely related to Bambusa emeiensis in Bambusodae

Genome-Wide Identification of MIKCc-Type MADS-Box Family Gene and Floral Organ Transcriptome Characterization in Ma Bamboo (<i>Dendrocalamus latiflorus</i> Munro)

Most bamboos die after flowering, and the molecular mechanisms responsible for flowering is poorly understood. The MIKCc-type MADS-box family gene is involved in the flowering process. To explore the mechanism of the MIKCc-type MADS-box gene and phytohormone regulation in the flowering of Dendrocalamus latiflorus Munro (D. latiflorus), characterized by extremely rapid growth and widely cultivated woody bamboo, we initially did a genome-wide analysis of the MIKCc-type MADS-box gene in D. latiflorus. In the meantime, transcriptome analysis was performed using the floral organs. A total of 170 MIKCc-Type MADS-Box genes were identified and divided into 15 categories. The cis-acting element analysis in promoters regions revealed that MIKC-type MADS-box family genes were associated with hormones, including auxin, abscisic acid (ABA), gibberellin (GA) and jasmonic acid (JA), which was found at 79, 476, 96, 486 sites and cover 61, 103, 73, 128 genes. Genome synteny analysis showed subgenome AA and BB were better than CC and obtained 49, 40, 39 synteny genes compared with Oryza sativa (O. sativa). In transcriptome analysis of floral organs, the enriched pathway from DEGs included circadian, vernalization and gibberellin pathways associated with the flowering process. We found that the jasmonic acid synthesis gene is highly expressed in the pistil, which may be the cause of Ma bamboo pollen abortion. The expression profile showed that most MIKC-type MADS-box genes exhibited high expression in flower organs. The consequences of this study will provide insight into the irregular flowering and low pollen counts of Ma bamboo

Effects of Enclosure Succession on the Morphological Characteristics and Nutrient Content of a Bamboo Whip System in a Moso Bamboo (<i>Phyllostachys edulis</i>) Forest on Wuyi Mountain, China

To investigate the morphological characteristics and nutrient content of bamboo whip systems in the Wuyi Mountain Moso bamboo (Phyllostachys edulis) forest in response to enclosure succession. The mixed Moso bamboo forests in the Wuyi Mountain Nature Reserve with 0, 4, 6, 11, 16, and 41 enclosure years were taken as the object of investigation. All the bamboo whips in the 2 m × 2 m sample plots were excavated layer-by-layer according to the soil layers of 0–20 cm, 20–40 cm, and 40–60 cm, and a total of 54 plots were dug. The morphological characteristics and nutrient contents of the Moso bamboo whips in the different soil layers were analyzed and evaluated. Enclosure management measures can not only effectively improve vegetation coverage, biodiversity, and biomass, but also improve soil moisture and nutrient status, indirectly affecting the vegetation, which is of great significance for preventing soil erosion. The results showed that the whip number, whip diameter, flagella number, whip length, and whip weight in the 0–20 cm soil layer were significantly increased by 169.2%, 11.0%, 197.5%, 113.7%, and 109.0% (p p p p p p p p p p < 0.05). In summary, enclosure measures were implemented for Moso bamboo forests in the Wuyi Mountain Nature Reserve, which promote the growth of Moso bamboo whips and optimize the structure of bamboo whips