AM Fungi and Piriformospora indica Improve Plant Growth of Pinus elliottii Seedlings

Pinus elliottii is an exotic afforestation pine extensively distributed in southern parts of China.In order to understand whether endophytic fungi can affect seedling growth of P.elliottii,Piriformospora indica(Pi),Funnelifcrmis mosseae(Fm),and Diversispora tortuosa(Dt)were inoculated respectively,and the non-inoculated group was set as control.The growth indexes,the contents of soluble sugar and soluble protein,and plant endogenous hormone levels in the leaves of P.elliottii,were analyzed.The results showed that Fm,Dt and Pi colonized the P.elliottii roots to form mycorrhizal structure and chlamydospores arranged in beads respectively.Three fungal inoculants exhibited the stimulated growth responses,whilst Dt illustrated the most positive effect on plant height,single fresh weight,trunk diameter and root system structure,compared with the control.On the other hand,the soluble sugar and soluble protein contents were increased distinctively in mycorrhizal plants.The endogenous IAA,GA3,ZR contents were increased,while the ABA contents were reduced in mycorrhizal plants versus non-mycorrhizal plants.The fungi-induced endogenous hormone changes triggered plant growth improvement of P.elliottii seedlings.This research unraveled the positive effect of AM fungi and P.indica on growth of pine seedlings,while,more application of endophytic fungi to fields needs to be explored.

Study on Pinus elliottii Plantations in Pengchang Forest Farm of Jingmen City

[Objectives]This study was conducted to improve the ecological and economic benefits of Pinus elliottii plantations in Pengchang Forest Farm, Jingmen City. [Methods] P. elliottii plantations in Pengchang Forest Farm in Jingmen City were selected as the research object, and the appearance and quantitative characteristics of P. elliottii community were studied and analyzed by a sampling method. [Results] Phanerophytes were the most in the P. elliottii community, accounting for 50%. In the community, except P. elliottii, the importance values of native plants were higher. The order of species diversity of P. elliottii community in Pengchang Forest Farm was herb layer, tree layer and shrub layer. The stress resistance of the community was weak, and strong intraspecific competition existed in P. elliottii. It is recommended to thin P. elliottii trees with insufficient lighting, poor growth potential and severely damaged tree body, and interplant Phoebe zhennan after thinning the P. elliottii plantations, so as to create a coniferous and broad-leaved evergreen mixed forest. [Conclusions] This study provides scientific support for thinning, tending, and forest management of P. elliottii plantations.

Antifungal Activity of Oleoresin and Fractions of Pinus elliottii Engelm and Pinus tropicalis against Phytopathogens

Microorganism resistance to the existing products is yet another difficulty that agriculturalists have to deal with. In this context, the search for new agricultural products that can fight phytopathogens has become increasingly important. Plants have played an important role in this process, because they can serve as a source of new compounds for drug discovery. Plants belonging to the genus Pinus produce an oleoresin that protects the plant against herbivores and pathogens. With a view to developing products that can combat fungal pathogens without harming the environment, this work aimed to evaluate the antifungal activity of the oleoresins and fractions of Pinus elliottii Engelm and Pinus tropicalis against phytopathogens. The methodology based on NCCLS M38-A standards aided antifungal activity assessment. The microdilution method helped to determine the Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC). The oleoresins of P. elliottii and P. tropicalis afforded the most significant results—they displayed fungicidal activity against all the tested species. MIC values were promising, especially the MIC of the oleoresin of P. elliottii against S. rolfsii (1.95 μg·mL-1). The MIC values of the oleoresins of P. elliottii and P. tropicalis ranged from 1.95 to 1000 μg·mL-1 and from 31.25 to 250 μg·mL-1, respectively. Fraction PT2 of P. tropicalis furnished the best results among all the assayed fractions: MIC values lay between 125 and 500 μg·mL-11. In conclusion, the oleoresin of P. tropicalis is a promising source of new antifungal agents for application in the treatment of phytopathogenic infections.

QTL detection for growth traits in Pinus elliottii var. elliottii and P. caribaea var. hondurensis

Quantitative trait locus （QTL） detection was carried out for growth traits in 122 F1 progenies of Pinus elliottiivar. elliottii （PEE） x tR caribaea var. hondurensis （PCH） hybrid. The PCH male parent linkage map contained 108 mark- ers in 16 linkage groups, while the PEE female parent contained 93 markers in 19 linkage groups. Sequence-related amplified polymorphism （SRAP）, microsatellite （SSR）, expressed sequence tag polymorphism （ESTP） and inter-simple sequence repeat （ISSR） were selected from an existing linkage map. Growth traits investigated were height at age five （HT05） and six years （HT06）, diameter at breast height at age five （DBH05） and six years （DBH06） and annual growth from age five to six years of height （AGHT） and diameter at breast height （AGDBH）. KruskaI-Wallis and interval mapping approaches were used to estimate levels of significance, the number of QTLs, the percentage of the phenotypic varia- tion explained by each of QTLs and their positions on the genetic linkage maps. Twenty six QTLs with significance levels p 〈 0.05 were detected on the parental maps for the six growth traits, which explained more than 15% of the phenotypic variation, suggesting an existence of major-effect genes. Several QTLs had the pleiotropy controlling more than one sin- gle growth trait. Overall, the proportion of phenotypic variation explained by QTLs ranged from 5.9% to 40.6% for HT05 and HT06, from 6.6% to 42.0% for DBH05 and DBH06 and from 5.8% to 22.3% for AGHT and AGDBH. The results from this study provide a basis for marker-aided selection （MAS） in PEE x PCH hybrids.

Influence of climate fluctuations on Pinus palustris growth and drought resilience

The longleaf pine(Pinus palustris Mill.)ecosystem is an endangered ecosystem in the southeastern USA,and efforts to restore the species are ongoing.However,in recent decades,the region has experienced drastic fluctuations between wet and dry growing season conditions from year to year,and it is not fully understood how these fluctuations have influenced the growth of P.palustris.To address this topic,we cored P.palustris trees in woodlands of southwest Georgia and used dendrochronology techniques to determine how climate fluctuations have influenced the growth and drought resilience of P.palustris.We also cored slash pine(Pinus elliottii Engelm.)trees in the same woodlands to compare growth between species.While P.palustris growth was less impacted by adverse climate conditions compared to P.elliottii,the strength of correlations between P.palustris growth and temperature,precipitation,and Palmer Drought Severity Index(PDSI)changed over time.In recent decades,climate conditions during the growing season became more influential on P.palustris growth than the previous year's conditions.This is concerning given that drought severity during the growing season has been increasing.Our results also indicate that P.palustris was less resilient to droughts during the 2000s and 2010s than to those of the 1950s.Under this new climate paradigm,our results suggest that P.palustris might be more susceptible to growth reductions and less resistant to droughts than once expected.This work highlights the importance of understanding the impact of novel climate conditions on P.palustris and has implications for restoration efforts,such as using silvicultural treatments that reduce tree vulnerability to drought(e.g.,thinning)and promote other climate-adapted species in mixture with P.palustris.

Early selection efficiency for fiber dimensions and their relationships with growth and wood quality for Pinus elliotth Engelm.in southern China

A solid understanding of the efficiency of early selection for fiber dimensions is a prerequisite for breeding slash pine(Pinus elliottii Engelm.)with improved properties for pulp and paper products.Genetic correlations between size of fibers,wood quality and growth properties are also important.To accomplish effective early selection for size of fibers and evaluate the impact for wood quality traits and ring widths,core samples were collected from360 trees of 20 open-pollinated Pinus elliottii families from three genetic trials.Cores were measured by SilviScan,and the age trends for phenotypic values,heritability,early-late genetic correlations,and early selection efficiency for fiber dimensions,such as tangential and radial fiber widths,fiber wall thickness and fiber coarseness,and their correlations with microfibril angle(MFA),modulus of elasticity(MOE),wood density and ring width were investigated.Different phenotypic trends were found for tangential and radial fiber widths while fiber coarseness and wall thickness curves were similar.Age trends of heritability based on area-weighted fiber dimensions were different.Low to moderate heritability from pith to bark(~0.5)was found for all fiber dimension across the three sites except for tangential fiber width and wall thickness at the Ganzhou site.Early-late genetic correlations were 0.9 after age of 9 years,and early selection for fiber dimensions could be effective due to strong genetic correlations.Our results showed moderate to strong positive genetic correlations for modulus of elasticity and density with fiber dimensions.The effects on fiber dimensions were weak or moderate when ring width or wood quality traits were selected alone.Estimates of efficiency for early selection indicated that the optimal age for radial fiber width and fiber coarseness was 6-7 years,while for tangential fiber width and wall thickness was 9-10 years.

Effect of fertilizer and water content on N_2O emission from three plantation soils in south China

The effects of fertilizers and water content on N2O emission were studied using the three most typical plantation soils. Soil incubations were performed and fertilization and water content treatments were designed. At 25% of saturated water content（SWC）, N2O emissions from the soil treated with urea, KNO3, （NH4）2 SO, and KH2 PO, were compared at application rates of 0, 100, 200, 300 and 500 kg/hm2. At 80% of SWC, similar experiments were carried out but at only one application rate（500 kg/hm^2）. N2O emissions at various water contents（20%, 35%, 50%, 65%, 80% and 100% of SWC） were studied. At low water content（25% of SWC）, neither nitrogen nor phosphorus（or potassium） fertilizers led to a high level of N2O emission, which generally ranged from 2.03 to 29.02 μg/（m^2·h）. However, at high water content（80% SWC）, the fertilizers resulted in much greater N2O emission irregardless of soil tested. The highest N2O emission rates after 24 h of water addition were 1233 lag/（ m^2 ·h） for S. superba soil, 1507 lag/（m^2 · h） for P. elliottii soil and 1869 lag/ （m^2 h） for A. mangium soil respectively. N2O emission from soils treated with urea, （NH4）2SO, and KH2PO, immediately dropped to a low level but steadily increased to a very high level for the soil treated with KNO3. High NO3^- content was a basis of high level of N2O emission. N2O emission rates from soils peaked shortly after flooding, rapidly dropping to a very low level in soil from non-legume plantations, but lasting for a relatively long period in soil from legume plantations. When soil water content increased equaling to or higher than 65%, the accumulated N2O emission over a period of 13 d ranged from 20.21-29.78 mg/m^2 for S. superba, 30.57-70.12 mg/m^2 for P. elliottii and 300.89-430.51 mg/m^2 for A. mangium. The critical water content was 50% of SWC, above which a high level of N2O emission could be expected, and below which very little N2O emissions were detected. The results suggest that, at low water content（ 〈 50% of SWC）, the fertilization practice is safe with regard to N2O emissions, but at high water content（ 〉 50% of SWC）, nitrogen fertilizer in the form of nitrate could yield a 100-fold increase in N2O emissions. Legume plantations like A. mangium should be avoided in low lands which could easily suffer from flooding or poor drainage.

Growth and yield of nine pine species in Angola

A species introduction experiment including several tropical pines and eucalypts was established in 1966/1967 in the Tchianga research station in Angolan Highlands. Despite 27 years of political conflict （1975-2002） and lack of management, the research experiment has remained relatively well conserved. We measured the best conserved plots that were 41 years old in 2007 to obtain information on the growth of different pine species. We calculated stand characteristics including basal area, dominant height, mean diameter, and stand volume for Pinus patula Schiede ex Schiltdl. Et Cham., Pinus pseudostrobus Lindl., Pinus kesiya Royle ex Gordon, Pinus devoniana Lindl., Pinus chiapensis （Martinez） Andresen, Pinus elliottii Engelm., Pinus greggii Engelm. Ex Parl., Pinus montezumae Lamb. and Pinus oocarpa Schiede ex Schltdl. The growing stock volume at 41 years was the highest in P. pseudostrobus, 1,325 m3^· ha^-1, followed by P. kesiya with 1,200 m^3· ha^-1. The widely planted P. patula had growing stock volume of 892 m^3· ha-^1. P. oocarpa and P. pseudostrobus had the highest stand basal area, over 80 m^2·ha^-1. Using increment core analyses we studied the temporal development of stand characteristics. Analysis of the mean annual increment （MAI） showed that rotation lengths of 20-30 years would maximize wood production. With these rotation lengths, the MAI of P. pseudostrobus would be 35 m^3· ha^-1. Other productive species were P. kesiya, P. ooearpa and P. chiapensis. P. patula had a maximum MAI of 20 m^3· ha^-1. P. greggii had the lowest mean annual volume production, only about 13 m^3· ha^-1.

Somatic Embryogenesis and Plantlet Regeneration in Callus Cultures Derived from Mature Zygotic Embryos of Slash Pine

White, translucent, and mucilaginous embryogenic callus was initiated in cultured mature zygotic embryoexplants of two different seed sources of slash pine(Pinus elliottii) on several culture media containing auxin and cytokinin.Somatic proembryos were induced on media containing 2,4-D and BA. Maturatiol1 was successfully achieved on mediumsupplemented with ABA. Somatic embryos germinated into regeneration plantlets On DCR medium containing activated charcoal. HiStological observatiol1 and scanning electron inicroscopic observatiol1 showed that proembryos derived from em-bryonal suspensor mass(ESM) were formed on the surface or the inside of embryogenic callus, and the prolitbration of pro-embryos was mainly from clcavage polyembryos.

Tree survival and maximum density of planted forests–Observations from South African spacing studies

Background：Among the most important aspects of risk and hazard studies relating to forest ecosystems are maximum forest density and density-dependent tree survival.Methods：Long-term observations about the maximum density of unthinned Pinus patula and P.elliottii field plots based on the Correlated Curve Trend（CCT）spacing studies which were established almost 8 decades ago by O’Connor（Forest Research with Special Reference to Planting Distances and Thinning,1935）in South Africa.Three specific approaches were introduced for analysing maximum density and tree survival,namely the‘limiting line’,Nilson’s sparsity and tree survival with the Weibull function.Results：The main results are：a）Maximum densities differ greatly among the two species grown on the same site and within the same species grown on different sites;it is possible to relate these differences to site index in both species.b）The relationship between the quadratic mean diameter and the minimum average spacing of surviving trees（known as Nilson’s Sparsity）appears to be surprisingly similar in both species.c）An analysis of tree survival in response to different initial planting espacements shows that the Weibull survival function parameters can be estimated if the initial planting density is known.This result is presented for each of the eight large experiments used in this study.Conclusions：This study contributes to a better understanding of tree survival and maximum density which are the key factors required for estimating risk and uncertainty.The risk of tree mortality is not constant,but varies with tree species,planting density,tree age and growing site.For estimating that risk,therefore,continuous long-term observation on different sites and with varying planting densities,as provided by the unthinned CCT series,are essential.

抗松针褐斑病湿地松胚性愈伤组织的超低温保存

本实验以抗松针褐斑病湿地松胚性愈伤组织27-1为材料,运用正交实验方法探究其超低温冷冻保存方法。结果表明:预培养时间、二甲基亚砜(DMSO)浓度、蔗糖浓度、聚乙二醇(PEG) 8000浓度和解冻温度对解冻后愈伤组织的活性均有显著影响。结合解冻后愈伤组织活力及其恢复生长情况,得出效果较好的超低温保存方法为:继代培养10~12 d生长状态良好的愈伤组织,添加0.5 mol/L蔗糖的高渗培养基预培养36 h;5%DMSO,15%PEG 4000,0.5 mol/L蔗糖3种冷冻保护剂组合使用,程序降温至-80℃停留30 min后投入液氮罐中保存;32℃水浴解冻,蔗糖溶液清洗后转接至LP培养基上恢复生长。在此程序处理下,冷冻90 d的愈伤组织1个月后可恢复再生,再生率最高达100%,再生愈伤组织生长状态良好并依然保持分化成熟体胚的能力。

Seasonal Variation of δ^13C of Four Tree Species： A Biological Integrator of Environmental Variables

Foliar δ^13C values, an indicator of long-term intercellular carbon dioxide concentration and, thus, of long-term water use efficiency （WUE） in plants, were measured for Pinus massoniana Lamb., P. elliottii Engelm., Cunninghamia laceolata （Lamb.） Hook., and Schima superba Gardn. et Champ. in a restored forest ecosystem in the Jiazhu River Basin. Seasonal variation and the relationship between the foliar δ^13C values of the four species and environmental factors （monthly total precipitation, monthly average air temperature, relative humidity, atmospheric pressure, and monthly total solar radiation and evaporation） were investigated. The monthly δ^13C values and WUE of the four species increased with increasing precipitation, air temperature, solar radiation, and evaporation, whereas δ^13C values of the four species decreased with increasing relative humidity and atmospheric pressure. Despite significant differences in δ^13C seasonal means for the four species, our results demonstrate a significant convergence in the responses of δ^13C values and WUE to seasonal variations in environmental factors among the species investigated and that the δ^13C signature for each species gives a strong indication of environmental variables.

湿加松增脂剂初步研究

为增加湿加松(Pinus elliottii×P.caribaea)产脂量,于2018年4-6月在桂东藤县埌南镇广西藤县通轩立信化学有限公司湿加松苗圃开展了pH值和不同浓度NAA、芸苔素内酯的促脂研究。研究结果表明pH值和NAA、芸苔素内酯对湿加松产脂均有影响。其中,pH值在3~5产脂量比对照提高18%以上,pH值为9的处理产脂量比对照提高40.9%;芸苔素内酯0.2 mg/L+NAA0.1 g/L处理产脂量比对照提高46.7%。