Culturing slowly growing tree seedlings is a potential approach for managing the conflict between the increasing demand for ornamental stock and the decreasing area of farmlands due to urbanization. In this study, Buddhist pine (Podocarpus macrophyllus [Thunb.] D. Don) seedlings were raised in multishelves with light-emitting diode lighting in the spectrum of 17:75:8 (red:green:blue) at 190–320 μmol m-2 s-1 with controlled temperature and relative humidity at 19.5°C and 60%, respectively. Seedlings were fed by exponential fertilization (EF) (nitrogen [N]-phosphorus [P]2O5-K2O, 10-7-9) at eight rates of 0 (control), 20 (E20), 40 (E40), 60 (E60), 80 (E80), 100 (E100), 120 (E120), and 140 (E140) mg N seedling-1 for four months through 16 fertilizer applications. The nutritional responses of Buddhist pine seedlings can be identified and classified into various stages in response to increasing doses, up to and over 120 N seedling-1. Morphological traits, i.e., the green color index and leaf area (LA) obtained by digital analysis and the fine root growth, all remained constant in response to doses that induced steady nutrient loading. LA had a positive relationship with most of the nutritional parameters. A dose range between 60 and 120 mg N seedling-1 was recommended for the culture of Buddhist pine seedlings. At this range of fertilizer doses, measuring the leaf area through digital scanning can easily and rapidly indicate the inherent nutrient status of the seedlings.
Target seedling cultivation pursues high quality and nutrient utilization instead of increasing growth and size. Exposure to light-emitting diode (LED) spectra is a well-known approach that can accelerate growing speed in tree seedlings, but it is still unknown whether seedling quality and nutrient utilization would be further improved with exogeneous polymer additives. Luohan pine (Podocarpus macrophyllus) seedlings were exposed to red (red-green-blue lights, 71.7%-13.7%-14.6%), green (26.2%-56.4%-17.4%), and blue (17.8%-33.7%-48.5%) LED-light spectra with half receiving leaf spray by chitosan oligosaccharides (Cos) at a rate of 2 ppm (w/w) and the other half receiving only water. The red-light spectrum promoted height, biomass, nutrient utilization, and quality assessment (DQI) in water-sprayed seedlings. The Cos spray enhanced fine-root growth, protein, and chlorophyll-b contents with elevated nutrient utilization and quality in seedlings in the green-light spectrum. DQI was found to have a positive relationship with phosphorus utilization. In conclusion, although the red-light LED spectrum can promote seedling growth, green light combined with Cos spray is recommended with the aim of maintaining seedling quality and increasing P utilization in Luohan pine seedlings.
Chinese fir (Cunninghamia lanceolate [Lamb.] Hook.) is a fast-growing species which is not only important as a timber-supplier, but also as an available sink for carbon (C) storage in biomass. Stand age and density are two critical factors that can determine tree C sequestration as interrelated drivers through natural self-thinning. C. lanceolate were planted using 1-year-old bare-root seedlings at the initial density of 1800 stems ha−1 in a 15-ha montane area of Hunan Province, China in 1987. The plantation was thinned twice 10 and 20 years after planting to leave trees of 437.5 ± 26.6, 675.0 ± 155.2 and 895.8 ± 60.1 stems ha−1 as low, medium, and high densities, respectively. Tree height and diameter at breast height (DBH) were measured every 2 years beginning from 23 years (2009) to 31 years (2018) after establishment, timber volume (TV) and biomass C were estimated accordingly. We did not find any interactive effect of age and density on any variables except for height. Both TV and biomass C increased with stand age or decreased in higher densities. The allometric height-DBH relationship can be fitted by an exponential rising-to-maximum model with higher maximum value over time. The decline of biomass C along density fit with the inverse first-order polynomial model which indicated that at least 1300–1500 stems ha−1 may be needed to maximize TV and biomass C for a longer term over 20 years. Therefore, to control the density to a reasonable level, over 1300 stems ha−1 in a rotation over 20 years old will be practical for tree biomass C in Chinese fir plantations.
Background Gaoben has a long history of application as medicine. There are few records of Liaogaoben in ancient books. The varieties of Ligusticum in practical application are confused. Therefore, it is very important to identify Ligusticum accurately. The phylogenetic position of Ligusticum in Umbelliferae needs to be determined. It is also of great significance to analyze the phylogeny of Ligusticum in Umbelliferae the difference of somatic genome. Methods Chloroplast (cp) genomic DNA was extracted from two species of Ligusticum and sequenced on Hiseq4000 light source. The sequence was assembled into contrags by soapenovo 2.04, aligned with reference genome by blast, and then corrected manually. Genereanation is performed by online dogma tools. The general characteristics of cp genomes of two species were analyzed, and compared with the relative species. The DNA of chloroplasts of higher plants is double stranded covalently closed loop molecule, and its length varies with species. According to the assembly genome sequence of the sequenced samples, combined with the prediction results of the coding genes, the genome of the samples was displayed in circles. After alignment, the evolutionary tree was constructed based on the single nucleotide polymorphism (SNP) of cp genome in 31 species by ML method. Results The whole chloroplast genome of Gaoben and Liaogaoben is 148,515 bp and 148,493 bp, both of which contain IR (IRa and IRb) LSC and SSC. 127 genes have been annotated, including 83 protein coding genes, 8 tRNA and 36 rRNA of all species, and 28 coding genes in IR region. There are six genes in the ATPase subunit of photosynthesis gene group, and there are obvious differences in the types of introns in NADH dehydrogenase subunit between them. In the comparative analysis of Pi value, two significant gene variation points are petG gene and psaL-ycf4 gene. The phylogenetic tree of the whole cp genome of SNP Umbelliferae was constructed, including 28 Umbelliferae and 3 Ligusticum. Conclusions In this study, the cp genomic characteristics of Ligusticum sinense and L. jeholense were identified, which provided a theoretical basis and documentation for the identification and phylogenetic analysis of Ligusticum.
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