Some ecophysiological characteristics of artà (Calligonum comosum Ľ Hérit) in response to drought stress

Water deficit is an important environmental factor restricting plant growth and photosynthesis. The effect of water deprivation on leaf water status, photosynthetic gas exchange, chlorophyll content and fluorescence parameters of artà (Calligonum comosum) was studied. Five-month-old artà seedlings, grown in pots in the open air, were subjected to one of four drought treatments (i.e., mild, moderate, severe and extreme drought stress) and compared to control seedlings (normal watering regime). Results show that leaf water potential, net photosynthesis, stomatal conductance, transpiration, photosynthetic pigment content (chlorophyll a and b) decreased with increasing levels of drought stress. Inactivation of the photosynthetic apparatus was accompanied by changes in the fluorescence characteristics, providing evidence that reduction of photosynthetic rate could be attributed to non-stomatal limitations. Alterations imply changes in photochemical conversion efficiency of photosystem II by which plants could reduce water transpiration or protect their photosynthetic apparatus from destruction. These adaptations are discussed in relation to the strategies developed to grow drought-resistant artà seedlings in desert environments.     

The effects of phenolic acid on nitrogen metabolism in Populus 3 euramericana ‘Neva’

The declines in soil fertility and productivity in continuously cropped poplar plantations are related to phenolic acid accumulation in the soil.Nitrogen is a vital life element for poplar and whether the accumulation of phenolic acid could influence nitrogen metabolism in poplar and thereby hinder continuous cropping is not clear.In this study, poplar cuttings of Populus × euramericana‘Neva’ were potted in vermiculite, and phenolic acids at three concentrations(0 X, 0.5 X and 1.0 X) were added according to the actual content(1.0 X) in the soil of a second-generation poplar plantation.Each treatment had eight replicates.We measured gas exchange parameters and the activities of key enzymes related to nitrogen metabolism in the leaves.Leaf photosynthetic parameters varied with the concentration of phenolic acids.The net photosynthetic rate(P_N) significantly decreased with increasing phenolic acid concentration, and non-stomatal factors might have been the primary limitation for P_N.The activities of nitrate reductase(NR), glutamine synthetase(GS) and glutamate synthase(GOGAT), as well as the contents of nitrate nitrogen, ammonium nitrogen, and total nitrogen in the leaves decreased with increasing phenolic acid concentration.This was significantly and positively related to P_N(P0.05).The low concentration of phenolic acids mainly affected the transformation process of NO_3~- to NO_2~-, while the high concentration of phenolic acids affected both processes, where NO_3~- was transferred to NO_2~- and NH_4~+ was transferred to glutamine(Gln).Overall, phenolic acid had significant inhibitory effects on the photosynthetic productivity of Populus × euramericana‘Neva’.This was probably due to its influence on the activities of nitrogen assimilation enzymes, which reduced the amount of amino acids that were translated into protein and enzymes.Improving the absorption and utilization of nitrogen by plants could help to overcome the problems caused by continuous cropping.     

Analysis on Insecticidal Activity of Bt Transgenic Populus deltoides × P.euramericana cv‘ Nanlin895’ and Its Effects on Soil Microorganism

以转Bt基因南林895杨株系B1、B4、B17、B21扦插苗为试验材料,分析其在室内和野外自然条件下对靶标害虫杨小舟蛾幼虫的抗虫性.结果表明:转Bt基因杨树4个株系均有一定的杀虫活性,其中株系B21对杨小舟蛾1龄幼虫12d校正死亡率高达95.3％；虫试表明转Bt基因杨树各株系扦植苗在野外自然条件下的12 d幼虫校正死亡率8月份为35.0％～88.8％,9月份为40.5％～95.3％.用转Bt基因杨树叶片饲养杨小舟蛾,对照植株杨小舟蛾幼虫化蛹率为83.3％～96.0％,而转Bt基因株系幼虫化蛹率为8.0％～76.7％,二者有显著差异.转Bt基因杨树对杨小舟蛾幼虫的生长发育有抑制作用,饲喂8d后害虫取食量、体质量增长速率显著低于对照.此外,为了解转Bt基因杨树对土壤微生物的影响,对转Bt基因杨树株系及对照进行了根际土壤微生物可培养类群的分析,初步结果显示:转Bt基因杨树根际土壤微生物中细菌、真菌、放线菌的数量与对照比较无显著差异.     

Influence of drought and salt stress on the growth of young Populus nigra ‘Italica’ plants and associated mycorrhizal fungi and non-mycorrhizal fungal endophytes

New Forests - Populus nigra ‘Italica’ (Lombardy poplar) is a breeding cultivar of black poplar, widely used as a street tree or windbreak, often exposed to salinity and limited water...     

Establishment of Efficient Regeneration System of Populus×euramericana cl.‘Bofeng’

Compared with the species of Leuce section,the difficulty in plant regeneration during tissue culture for the species of Aigeiros section is a key limiting factor for their application in genetic engineering of forest trees.In this study,the plant growth regulators combination,copper concentration,light intensity,and the selection pressures of kanamycin were investigated using leaves of Populus×euramericana cl.’Bofeng’ as explants,and a stable and high efficient regeneration system was established.Using this system,both the shoot regeneration rate and rooting rate were up to 100%,and the average number of differentiated shoots in each leaf explant was up to 20,and the survival rate of seedlings reached 98%.The optimal selection pressure of kanamycin in shoot inducement for leaf-explant was 40 mg·L^-1,and the optimal selection pressure of kanamycin in root inducement of adventitious bud was 20 mg·L^-1.The authors also found that differentiation rate of adventitious buds of P.×euramericana cl.’Bofeng’ could be significantly promoted by increased copper concentration,and this is the first report about the key role of copper（Cu） in explant regeneration of Poplars.This regeneration system with high frequency which was established by the authors was as good as that of species of Leuce section,and it provides a good technological platform for genetic engineering of forest tree which uses the species of Aigeiros section as model materials.     

Establishment of an Efficient Regeneration System of Populus × euramericana cl.‘ Bofeng 1’

与白杨派树种相比,黑杨派树种一直因组培再生困难而限制了其在林木基因工程研究中的应用.本文以欧美杨优良新品种——渤丰1号为试验材料,以其再生培养基中的植物生长调节剂配比、铜离子浓度、光照强度、卡那霉素选择压等方面为切入点开展研究,建立了渤丰1号杨高效组培再生体系.使用该再生体系时,外植体的分化率和生根率均达100％,叶片的平均分化芽数多达20个以上,组培苗移植成活率可达98％,40 mg· L-1卡那霉素可以抑制渤丰1号杨叶片的诱导与分化,20 mg· L-1卡那霉素可以抑制渤丰1号杨不定芽的生根；同时发现铜(Cu)元素是渤丰1号杨外植体分化再生的一个关键因素,增加Cu2+浓度能显著促进不定芽的诱导和分化.     

Protective enzyme activity and physiological properties of four mulberry varieties affected by drought stress in the Panxi Region of Sichuan Province, China

In order to identify the effects of drought stress on protective enzyme activity and physiological properties, four mulberry varieties, i.e.,‘Nanye-1’, ‘Yunsang-1’, ‘Xinyizhilai’ and ‘Husang-32’ in the Panxi Region of Sichuan Province, China, were selected. The activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in four mulberry varieties was determined. Soluble protein, soluble sugar, proline, net photosynthetic rate and transpiration rate of mulberry leaves were analyzed. The resul...     

Effects of ethylene and (Z)-hexen-3-al on production of volatiles in Populus simonii × P. pyramidalis ‘Opera 8277’ cuttings

We studied the effects of ethylene, (Z)-hexen-3-al, combinations of ethylene and (Z)-hexen-3-al, methyl jasmonate on the release of terpenoids and green leaf volatiles (GLVs) of Populus simonii × P. pyramidalis ‘Opera 8277’ by fumigation. The results show that exposure to ethylene alone did not induce volatiles. However, it was induced by exposure to combinations of (Z)-hexen-3-al and ethylene, a large amount of hexenal and hexen-3-ol as compared to sole (Z)-hexen-3-al exposure, which indicated that the release of wounding signals of P. simonii × P. pyramidalis ‘Opera 8277’ could be synergized by ethylene and (Z)-hexen-3-al. __________ Translated from Journal of Northwest Forestry University, 2008, 23(2): 143–146 [译自: 西北林学院学报]     

Effects of sludge on germination and initial growth performance of Leucaena leucocephala seedlings in the nursery

A study was carried out to determine the influence of different types of sludges （municipal, industrial and residential） on field germination, growth and nodulation of L. leucocephala seedlings in the nursery. Before sowing of seeds, different combinations of sludges were incorporated with the nutrient deficient natural forest soils. Field germination, nodulation status and physical growth parameters of seedlings （shoot and root length, vigor index, collar diameter, leaf number, fresh and dry weight of shoot and root and total dry biomass increment） were recorded after three and six months of seed sowing. Field germination, nodulation status and growth parameters were varied significantly in the soil amended with sludges in comparison to control. The highest number of nodule was recorded from soil amended with residential sludge （ 1：1 ） and highest fresh and dry nodule weight was also found from the same combination in both three and six month old seedlings. In case of growth parameters, the highest growth was recorded from soil and residential sludge （ 1：1 ） combination compared to control. From the study, it can be recommended that soil amended with residential sludge （ 1：1 ） provide better field germination, growth and nodule formation of L. leucocephala in degraded soil.     

Effects of land use changes for ecological restoration on soil moisture on the Chinese Loess Plateau:a meta-analytical approach

Soil moisture is an important resource for plant growth on the arid and semi-arid Loess Plateau of China where the‘‘Grain for Green’’project was launched in 1999,but there has been no systematic evaluation of soil moisture from the effects of ecological restoration at a regional scale.We systematically assessed 63 published studies during 2000-2015,including 2050 observations at 68 sites on the Loess Plateau with the aim of determining soil moisture changes and the factors influencing those changes.We found that,after land use conversion,soil moisture decreased by 17%in the upper 100 cm soil layer and that tree plantations and shrub lands appeared to cause soil moisture depletion which became increasingly serious with soil depth.The decrease of soil moisture was significantly influenced by the planting species in all restoration types(tree plantations,shrub lands,and grasslands).We also found that tree plantations and grasslands converted from farmlands consumed more soil moisture than from wasteland(including bare land,abandoned land and wild grasslands).Artificial restoration led to significant soil moisture reduction,but natural restoration had little effect on soil moisture.Therefore,natural restoration should be an alternative restoration practice on the Loess Plateau.These results will provide helpful information for artificial afforestation and planning ecological restoration campaigns for policy makers on water-limited regions.     

Changes induced by osmotic stress in the morphology,biochemistry, physiology,anatomy and stomatal parameters of almond species （Prunus L. spp.） grown in vitro

We investigated the influence of different levels of osmotic stress on growth and development in selected wild almond species(eight Prunus spp.) grown in vitro. The study, while endorsing the efficacy of in vitro screening of auxiliary buds of wild almond for osmotic stress tolerance, showed species variability in its response to osmotic stress. Osmotic stress reduced growth and development of all the species. However, the putative tolerant Prunus spp. showed better performance than the putative susceptible genotypes. On average there was an 80% decrease in shoot dry weight at-1.2 MPa. Reduction in shoot weight was more common in osmotic stress-susceptible species in the section labeled ‘Euamygdalus'. The tolerant Prunus species produced smaller changes in biochemical responses than the sensitive cultivars for malondialdehyde content, catalase activity, relative permeability of protoplast membranes, and net photosynthetic rate. The tolerant species maintained cell integrity better than drought sensitive species. Wild almond species in the section labeled ‘Spartioides'(Prunus arabica(Olivier) Neikle, Prunus glauca (Browicz) A.E. Murray, Prunus scoparia Spach) and ‘Lycioides'(Prunus lycioides Spach, Prunus reuteri Bossi. et Bushe) were best adapted to osmotic stress. Increase in chlorophyll concentration and leaf thickness under high osmotic stress can be considered as preliminary selection parameters for osmotic stress tolerance in Prunus spp. The study confirmed the efficacy of the in vitro method for screening of large number of genotypes for osmotic stress tolerance in wild almond species.