A model for vertical distribution of fine roots in Robinia pseudoacacia plantations on the Loess Plateau

Based on a detailed investigation of vertical distributions of fine roots in Robinia pseudoacacia plantations at the Ansai Soil and Water Conservation Station, Shaanxi Province, a model was developed for the deep distribution of fine roots of R. pseudoacacia, which reflects the growth of fine roots affected by the mixed process of infiltration water and deep soil water. The maximum depth of the distribution h _max and the depth of the highest fine root density (FRD) h _p were determined and the maximum depth of infiltration water supplied for fine root growth h _q could also be calculated, h _q was considered as the approximate boundary between infiltration water and deep soil water in support of the growth of fine roots. According to the model, the soil water of R. pseudoacacia woodland in the profile could be classified into three layers: the first layer from the soil surface to h _p was the active water exchange layer, very much affected by precipitation; the second was the soil water attenuation layer, between h _p and h _q and largely affected by the vertical distribution of fine roots; the third was the relatively stable soil water layer below h _q, below which soil water did not change much. The percentage of infiltration water supplied for the growth of fine roots reached a level of 88.32% on the shaded slopes and 85.21% on sunny slopes. This indicated infiltration of precipitation played a crucial role in the growth of R. pseudoacacia in the gully region of the Loess Plateau. The research of interaction between the distribution of fine roots and soil water in the profile will help to explain the reasons for the complete drying out of soils and provide a theoretical basis for continuing the policy of matching tree species with sites on the Loess Plateau. Translated from Scientia Silvae Sinicae, 2006, 42(6): 40–48 [译自: 林业科学]     

The runoff characteristics and harmonic analysis of the soil moisture dynamics in<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> stand

Robinia pseudoacacia stands act as a typical ecological protection forest in hilly semi-arid area of China. Two fields of surface runoff were separately set up inR. pseudoacacia stand and its clearcut area in the western Liaoning Province (18°50’–122°25’ E, 40°24’–42°34’ N) for measuring the characteristics of runoff and sediment as well as soil moisture dynamics. Contractive analysis of the two land types showed that there existed a significant difference in volumes of runoff and sediment between the sites ofR. pseudoacacia stand and its clearcut area. The runoff volume and sediment volume in clearcut are were much bigger than those inR. pseudoacacia stand, with an increase amount of 40%–177% for runoff and 180%–400% for sediment. Hydrograph of surface runoff of typical rainfall showed that the peak value of runoff inR. pseudoacacia stand was decreased by 1.0–2.5×10⁻³m³·s⁻¹ compared with that in its clearcut area, and the occurring time of peak value of runoff inR. pseudoacacia stand was 10–20 min later than that in its clearcut area. Harmonic analysis of soil moisture dynamics indicated that the soil moisture inR. pseudoacacia stand was 2.3% higher than that in clearcut area, and the soil moisture both inR. pseudoacia stand and its clearcut area could be divided into dry season and humid season and varied periodically with annual raifall precipitation. It was concluded thatR. pseudoacacia stand plays a very important role in storing water, increasing soil moisture, and reducing surface runoff and soil erosion. Foundation item: This paper was supported by Chinese “863” Plan Water-Saving Agriculture (2002AA2Z4321), the Key Knowledge Innovation Project (SCXZY0103), and The “Tenth-five” Plan of Liaoning Province (2001212001). Biography: GAO Peng (1967-), male, Dr. candidate, associate professor of Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China. Responsible editor: Song Funan     

Correlation of eco-hydrographic benefit and height increment of Robinia pseudoacacia stand with climatic environmental factors in Yellow River Delta Wetland of China

The relationship between eco-hydrographic benefit of forest vegetation and climatic environmental factors is one of the focuses in the research on environmental protection and ecosystem countermeasures in Wetland. The runoff, sediment and soil moisture rate dynamics in Robinia pseudoacacia plantation and its clearcut area were investigated in the natural runoff experiment plots in Yellow River Delta Wetland, Shandong Province, China. The correlation of height increment of R. pseudoacacia with nine climate factors such as light, water, heat, etc. was analyzed by stepwise regression analysis. The results showed that the amounts of runoff and sediment in clearcut area of R. pseudoacacia were 53.9%–150.8% and 172.8%–387.1% higher than that in Robinia pseudoacacia plantation, respectively. The runoff peak value in R. pseudoacacia stand was obviously lower than that in clerarcut area, meantime, the occurrence of runoff peak in R. pseudoacacia stand was 25 min later than in its clerarcut area. The soil moisture rates in R. pseudoacacia stand and its clearcut varied periodically with annual rainfall precipitation in both dry season and humid season. The annual mean soil moisture rate in R. pseudoacacia stand was 23.3%–25.6% higher than that in its clearcut area. Meanwhile, a regression model reflecting the correlation between the height increment of R. pseudoacacia and climatic factors was developed by stepwise regression procedure method. It showed that the light was the most important factor for the height increment of R. pseudoacacia, followed by water and heat factors. Foundation project: Subsidized by the National “11th Five Year” Plan of Science and technology (2006BAD26B06, 2006BAD03A1205) and Ecological Restore Project of Water Resources Ministry of China (2006-2008).     

Thermogenetic curves and thermokinetics of seed germination ofRobinia pseudoacaia

Seed germination process has closely relation with material transformation and energy exchange within the seed. Study on its thermal effect is important for understanding the mechanism and the influencing factors of the seed germination. The thermogenetic curves of seed germination ofRobinia pseudoacacia was measured by a new-type conductive microcalorimeter made in Wuhan University. The relationship was analyzed between the germination thermogenetic regulation and seed germination physiology. The thermogentic curves were further analyzed by thermokinetic theory to obtain the dynamic parameters and the thermokinetic model on seed germination ofRobinia pseudoacacia. The relationship of the thermogenetic power (μ w) and the germination time(h) of the germination process of 20 grainsRobinia pseudocacia seeds at 25°C wasP=208.77/[0.1937+0.8063exp(−0.06563t)] Foundation item: This project is supported by National Nature Science Foundation (30070200). Biography: Hu Yun-chu (1960-), male, associated Prof. in Central South Forestry University, Zhuzhou 412006, Hunan, P. R. China. Responsible editor: Song Funan     

非生长季刺槐林土壤CH4通量的变化特征及其影响因子

[目的]探讨在非生长季不同天气条件下45年生刺槐林土壤CH₄通量的日变化和季节变化特征,并确定其主要影响因子.[方法]2014年10月-2015年4月(非生长季),在华北低山丘陵区黄河小浪底森林生态系统定位研究站,利用基于离轴积分腔输出光谱技术的土壤CH₄通量自动观测系统,对土壤CH₄通量进行连续观测,同步观测林内大气温度和相对湿度、5 cm深处土壤温度和土壤湿度、林内总辐射以及降雨量,分析各因子间的相互关系并确定影响土壤CH₄通量的主要因子.[结果]表明:(1)在非生长季,刺槐人工林土壤为大气CH₄重要的汇,变化范围为-0.15~-2.34 nmol·m^-2·s^-1 .晴天的林地土壤吸收CH₄能力 (-0.78 nmol·m^-2·s^-1) 明显高于阴天(-0.61 nmol·m^-2·s^-1)、降雨或降雪天气 (-0.58 nmol·m^-2·s^-1),而且呈"V"型日际变化特征;在2014年11月-2015年1月,土壤吸收CH₄能力逐渐下降,并维持相对较低的水平,直至2015年3月达到最大值 (-2.34 nmol·m^-2·s^-1);(2)土壤CH₄通量与大气温度、5 cm深处土壤温度呈显著负相关,与相对湿度呈正相关;在2015年1月,土壤CH₄通量与总辐射呈正相关;(3)在生长末期土壤上冻阶段和冬季土壤冻结阶段,大气温度和相对湿度为影响土壤CH₄通量的主要因子;而在生长季初期,主要的影响因子为大气温度和5 cm深处土壤温度.[结论]非生长季刺槐林土壤表现为大气CH₄的汇,在非生长季初期土壤吸收CH₄的能力最弱,主要受大气温度和相对湿度的影响,而在非生长季末期土壤吸收CH₄的能力逐渐增加,主要受大气温度和土壤温度的影响.     

Evolution of soil microbial biomass in restoration process of Robinia pseudoacacia plantations in an eroded environment

Vegetation recovery is a key measure to improve ecosystems in the Loess Plateau in China. To understand the evolution of soil microorganisms in forest plantations in the hilly areas of the Loess Plateau, the soil microbial biomass, microbial respiration and physical and chemical properties of the soil of Robinia pseudoacacia plantations were studied. In this study, eight forest soils of different age classes were used to study the evolution of soil microbial biomass, while a farmland and a native forest community of Platycladus orientalis L. were chosen as controls. By measuring soil microbial biomass, metabolic quotient, and physical and chemical properties, it can be concluded that soil quality was improved steadily after planting. Soil microbial biomass of C, N and P (SMBC, SMBN and SMBP) increased significantly after 10 to 15 years of afforestation and vegetation recovery. A relatively stable state of soil microbial biomass was maintained in near-mature or mature plantations. There was an increase of soil microbial biomass appearing at the end of the mature stage. After 50 years of afforestation and vegetation recovery, compared with those in farmland, the soil microbial biomass of C, N and P increased by 213%, 201% and 83% respectively, but only accounting for 51%, 55% and 61% of the increase in P. orientalis forest. Microbial soil respiration was enhanced in the early stages, and then weakened in the later stage after restoration, which was different from the change of soil organic carbon. The metabolic quotient (qCO₂) was significantly higher in the soils of the P. orientalis forest than that in farmland at the early restoration stage and then decreased rapidly. After 25 years of afforestation and vegetation recovery, qCO₂ in soils of the R. pseudoacacia forest was lower than that in the farmland soil, and reached a minimum after 50 years, which was close to that of the P. orientalis forest. A significant relationship was found among soil microbial biomass, qCO₂ and physical and chemical properties and restoration duration. Therefore, we conclude that it is possible to artificially improve the ecological environment and soil quality in the hilly area of the Loess Plateau; a long time, even more than 100 years, is needed to reach the climax of the present natural forest. __________ Translated from Acta Ecologica Sinica, 2007, 27(3): 909–917 [译自: 生态学报]     

Characteristics of leaf areas of plantations in semiarid hills and gully loess regions

The objectives of our study were to explore the relationship of leaf area and stand density and to find a convenient way to measure stand leaf areas. During the 2004 growing season, from May to October, we used direct and indirect methods to measure the seasonal variation of the leaf areas of tree and shrub species. The trees were from Robinia pseudoacacia stands of four densities (3333 plants/hm², 1666 plants/hm², 1111 plants/hm², and 833 plants/hm²) and Platycladus orientalis stands of three densities (3333 plants/hm², 1666 plants/hm², and 1111 plants/hm²). The shrub species were Caragana korshinskii, Hippophae rhamnoides, and Amorpha fruticosa. Based on our survey data, empirical formulas for calculating leaf area were obtained by correlating leaf fresh weight, diameter of base branches, and leaf areas. Our results show the following: 1) in September, the leaf area and leaf area index (LAI) of trees (R. pseudoacacia and P. orientalis) reached their maximum values, with LAI peak values of 10.5 and 3.2, respectively. In August, the leaf area and LAI of shrubs (C. korshinskii, H. rhamnoides, and A. fruticosa) reached their maximum values, with LAI peak values of 1.195, 1.123, and 1.882, respectively. 2) There is a statistically significant power relation between leaf area and leaf fresh weight for R. pseudoacacia. There are significant linear relationships between leaf area and leaf fresh weight for P. orientalis, C. korshinskii, H. rhamnoides, and A. fruticosa. Moreover, there is also a significant power relation between leaf area and diameter of base branches for C. korshinskii. There are significant linear relations between leaf area and diameter of base branches of H. rhamnoides and A. fruticosa. 3) In the hills and gully regions of the Loess Plateau, the LAIs of R. pseudoacacia stand at different densities converged after the planted stands entered their fast growth stage. Their LAI do not seem to be affected by its initial and current density. The same is true for P. orientalis stands. However, the leaf area of individual trees is negatively and linearly related with stand density. We conclude that, in the hills and gully regions of the Loess Plateau, the bearing capacity of R. pseudoacacia and P. orientalis stands we studied have reached their maximum limitation, owing to restricted access to soil water. Therefore, in consideration of improving the quality of single trees, a stand density not exceeding 833 and 1111 plants/hm² is recommended for R. pseudoacacia and P. orientalis, respectively. In consideration of improving the quality of the entire stands, the density can be reduced even a little more. __________ Translated from Journal of Plant Ecology (Chinese Version), 2008, 32 (2): 440–447 [译自: 植物生态学报]     

The distribution of <Emphasis Type="Italic">Obolodiplosis robiniae</Emphasis> on black locust in Slovakia

For the first time during October 2006, the occurrence of Obolodiplosis robiniae (Haldeman 1847) (Diptera: Cecidomyiidae) was recorded on the black locust (Robinia pseudoacacia L.) in Slovakia. During 2007, field surveys were undertaken to determine the distribution of the species and the infestation ratio at different locations. One year after its first discovery, O. robiniae was found throughout southern Slovakia. The gall midge was observed in 148 out of 161 checked locations. The infestation ratio of single leaves varied from 4 to 100%. The infestation ratio of the black locust tree was evaluated during May–June, July–August, and September–October, and accounted for 15–39, 9–53, and 6–49%, respectively. The most frequent infestation ratio fluctuated from 10 to 30% (115 locations). The highest infestation was recorded during July–August. Greater infestation was prevalent in the larger settlements than it was in the countryside. The gall midge was also recorded on R. viscosa Vent. Although the results show that O. robiniae is nowadays an usual insect with high potential to become an important pest of ornamental black locust or biological control agent against weedy black locust in southern Slovakia, the species do not appear to have reached pest status until now.     

Changes in size of soil seed bank in Robinia pseudoacacia L. (Leguminosae), an exotic tall tree species in Japan: Impacts of stand growth and apicultural utilization

This study examined the factors that influence the size of a soil seed bank in Robinia pseudoacacia stands. We proposed two hypotheses: the amount of buried seeds of R. pseudoacacia is proportional to stand biomass rather than stand age, and apicultural utilization influences the size of the soil seed bank. R. pseudoacacia generally produces seeds with various degrees of physical dormancy. In addition, this tree is short-lived, and fecundity declines after 30–40 years in relation to tree vigor. However, R. pseudoacacia is intensively used in apiculture as an important honey source, and supply of honeybees by beekeepers could influence seed crops. We investigated 25 plantations in Hokkaido (Central, Hidaka, and Oshima) and in Nagano, Japan, where many naturally regenerated R. pseudoacacia stands occur. We found great variation in the size of the soil seed bank among stands, ranging from 13,757 to 6.4 seeds m⁻² per plot. A generalized linear mixed model revealed that both basal area (BA_Rp) and apicultural utilization best explained the size of the soil seed bank. Both the positive effect of BA_Rp and small contribution of stand age to the model implied that the soil seed bank is transitory, and will not persist for very long time. The large contribution of apicultural utilization to the size of the soil seed bank implied pollinator limitation under natural conditions. R. pseudoacacia often has large flower crops, and native pollinators can not keep up with the demand for pollination. Thus, the supply of honeybees by beekeepers should improve the pollination success of R. pseudoacacia. From these results, we conclude that we must consider stand history with respect to apicultural utilization if the land is harvested or a stand declines.     

Effect of auxins (IBA and NAA) and season on rooting of juvenile and mature hardwood cuttings of Robinia pseudoacacia and Grewia optiva

Juvenile (2 year old trees) and mature hardwood (15 year old trees) cuttings of Robinia pseudoacacia and Grewia optiva were tested for their capacity to form roots. Cuttings were prepared in spring, monsoon and winter seasons and treated with different concentrations (250, 500 and 750 mg/l) of IBA and NAA. These were planted in a mist chamber maintained at 25±1°C with relative humidity >70%. Juvenile cuttings of both species rooted significantly better than mature hardwood cuttings in all three seasons, and the age effect was more pronounced in auxin treated cuttings. The highest rooting in juvenile (83.3%) and mature (66.6%) cuttings was observed with the NAA (500 mg/l) treatment in R. pseudoacacia during the spring season. In G. optiva, IBA (250 mg/l) in the monsoon season was most effective and yielding a maximum of 80% and 70% rooting in juvenile and mature cuttings, respectively. Auxin treatments also significantly enhanced the number of roots, root length, leaf number and leaf area. Statistical analysis of data revealed that interactions between age, season and treatments were significant at P <0.05 level for R. pseudoacacia and non-significant for G. optiva.     

Comparison of gene delivery methods for transformation ofRobinia pseudoacacia L. by Ti-plasmid

The binary vector plasmid pIG121-Hm carrying the chimeric neomycin phosphotransferase (npt II), β-glucuronidase (gusA) and hygromycin phosphotransferase (hpt) genes was delivered intoRobinia pseudoacacia L. callus using theAgrobacterium tumefaciens-mediated transformation method and particle gun transformation method. It was determined that adding 10 mg/L of acetosyringone toAgrobacterium infection medium and callus-Agrobacterium co-culture medium could increaseAgrobacterium-mediated transformation efficiency. In contrast, particle gun transformation could successfully deliver plasmid DNA into the callus, but its transformation efficiency was lower and gene expression was transient in comparison with theAgrobacterium-mediated method, suggesting that substantially stronger promoters might be required.     

Plantlets regeneration from root explants ofRobinia pseudoacacia L. by suspension culture

A rapid and efficient method for the regeneration of plantlets from root explants ofRobinia pseudoacacia L. by suspension culture was established. The roots taken from aseptically grown 15-day-old seedlings were used as explants. It was determined that photoperiodicity was necessary for root proliferation, and that the promotive effect of IAA (3-indoleacetic acid) on root proliferation was better than that of IBA (3-indolebutyric acid). The roots cultured in 1/2 MS liquid medium containing 3 μM IAA and 1% sucrose at 25°C under 16-hour photoperiod with 50 μmol m⁻²s⁻¹ PPFD (photosynthetic photon flux density) shaking at 100 times/min reciprocally showed high efficiency for root proliferation. BAP (6-benzylaminopurine) was found to be essential to induce adventitious shoots from the roots, and the roots cultured in the medium supplied with 3 μM BAP combined with 1–6 μM IAA for 3 weeks under the same conditions as in the root proliferation period were most suitable for adventitious shoot inducement.     

Variation in germination character of Robinia pseudoacacia L. (Leguminosae) seeds at individual tree level

To demonstrate the seed dormancy and germination characters of Robinia pseudoacacia L., an exotic tall tree species in Japan, we applied scarification, cold stratification, diurnal thermal regime, heat shock, and/or winter weathering treatments to the seeds. These characters differed markedly among three seed sources (Trees K, B, and I). Scarification revealed that most seeds from Tree K showed physical dormancy, whereas those from Tree B had no physical dormancy. The seeds from Tree I showed weak physical dormancy so that the seeds eventually germinate without any treatments as time goes by. The physical dormancy in Tree K was broken by a long, high heat shock treatment. The results imply that seeds from Tree K respond to fire in natural conditions. Seeds from Tree I responded to a wide range of thermal regimes, except for long, high heat shock. In contrast, most seeds from Tree B absorbed water during cold stratification and some germinated. However, many seeds from Tree B died in the soil during the winter, presumably because of microbial and fungal infections. Seeds from Trees I and B acquired physical dormancy by weathering during the winter, implying that seedpods that remain in the crown function as an aerial seed bank. R. pseudoacacia may be able to produce various levels in dormancy with respect to the winter condition.     

匈牙利刺槐（（Robinia pseudoacacia L.）林的经营研究

匈牙利刺槐（（Robinia pseudoacacia L.)是在17世纪初从北美引入到欧洲的第个森林树种。在匈牙利，刺槐是非常重要的速生树种，为经济和生态目的，可以成功营造刺槐人工林。结合该树种的生长特点选择营林措施，可以最大限度的提高刺槐人工林的成活率和生产力。本文根据林分结构和森林产量长期实验林的研究成果，提出了刺槐林的抚育作业次序。制定好的营林计划和模式将会培育出效益刺槐林，并能使土地经营者更好地接受该树种。同时，刺槐也是一个非常有用的能源生产树种，本文展示了对这方面的研究成果。图2表1参8。     

Effects of brassinolide on the survival,growth and drought resistance of <Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> seedlings under water-stress

We conducted field and pot experiments to investigate the effects of brassinolide on 1-year-old Robinia pseudoacacia L. seedlings. In the field experiment, seedling roots were soaked in brassinolide solutions containing 0–0.4 mg/l pure brassinolide before planting. Survival and growth of the seedlings were determined 8 months later. The results showed that soaking roots in brassinolide prior to planting significantly increased the survival and growth of seedlings. The best results were in the 0.2 mg/l brassinolide treatment. In the pot experiment, roots were soaked in 0–0.4 mg/l brassinolide before planting followed by a foliar application of brassinolide when the seedlings leafed out. After the seedlings were established, the soil water content in the pots was regulated to simulate drought conditions and various physiological parameters were measured. The results showed that treatment with 0.2 mg/l brassinolide decreased the transpiration rate, stomatal conductance and malondialdehyde (MDA) content of seedlings growing under moderate or severe water stress compared to untreated seedlings. Leaf water content, predawn water potential, soluble sugar content, free proline content, and superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities were all greater in water-stressed seedlings in the 0.2 mg/l brassinolide treatment compared to the control. The results indicate that the application of brassinolide can ameliorate the effects of water stress and enhance drought resistance of Robinia seedlings. Treatment of seedlings with brassinolide may be a useful management tool for afforestation projects in arid and semiarid areas.     

滇杨多倍体苗期叶片形态及光合生理比较分析

[目的]以前期研究诱导获得的滇杨种质为试验材料,比较分析其苗期叶片形态及光合生理与基因剂量的关系,为滇杨多倍体育种提供理论指导。[方法]利用前期研究所获得的滇杨多倍体当年生苗为材料,测定其叶片大小、叶片厚度、栅栏组织厚度、气孔特性及叶绿素含量,并以滇杨二倍体为对照,分析滇杨不同程度多倍化后的叶片形态及光合生理特性。[结果]表明:嵌合体及四倍体滇杨的叶片长、宽均大于二倍体植株;滇杨嵌合体及四倍体叶片厚度分别为二倍体的1.16、1.41倍,栅栏组织厚度分别为二倍体的1.10、1.23倍,叶片单位视野内气孔数明显少于二倍体,气孔体积则大于二倍体,叶绿素总含量分别为二倍体的127%和141%;滇杨嵌合体及四倍体植株的净光合速率在日变化过程中均高于二倍体;气孔导度、蒸腾速率则与二倍体差别较小;嵌合体、四倍体及二倍体的胞间CO₂浓度在日变化过程中变化不明显。 [结论]滇杨多倍化后,由于其基因数量的增加,在叶片形态及光合生理特性等方面,表现出了明显区别于其二倍体的剂量效应。     

An evaluation of scarification methods for seeds of two leguminous trees

Twenty different methods of seedcoat scarification were tested on Gleditsia triacanthos L. and Robinia pseudoacacia L. to find an alternative to acid scarification for these species. For germination testing, nicking or burning were best, and these same methods could be used in small nurseries with adequate labor. For larger quantities, hot water soaks or heat shock soak treatments yielded satisfactory, though lower, germination.     

Effect of inoculation with ecto- and arbuscular mycorrhizae and Rhizobium on the growth and nitrogen fixation by black locust,Robinia pseudoacacia

Experiments were made to determine the effect of inoculation withRhizobium, the ectomycorrhizal fungus Hebelomamesophasem and the arbuscular mycorrhizal fungus Glomuscaledonium on the growth and nitrogen fixation of black locust(Robinia pseudoacacia Linn.) seedlings grown invitro and in pot culture. The results showed that both mycorrhizalfungi and Rhizobium stimulated the growth and nitrogenfixing ability of inoculated seedlings. Inoculation with all three microbestogether produced the most beneficial effects on nitrogen fixation, mycorrhizaldevelopment and seedling growth.     

Selection, regeneration and protein profile characteristics of NaCl-tolerant callus ofRobinia pseudoacacia L.

Changes in callus growth, differentiation potency and protein profile induced by salt stress were investigated in the calli induced from a hypocotyl ofRobinia pseudoacacia L. The NaCl treatment evidently obstructed the callus growth and the influences seemed to continue to be present in the selected calli even after they were restored in NaCl-free medium that could partially recover the callus growth, and some polypeptides were found to restore. The calli selected and restored intermittently every two weeks for one year completely lost their differentiation potency. The NaCl-tolerance test of the regenerated plantlets revealed that part of the plantlets that directly regenerated from the selected NaCl-tolerant calli were able to survive in 0.2 M NaCl, while most of the plantlets regenerated from the NaCl-nonselected calli or from restored calli were obviously damaged by this treatment. The SDS-PAGE assay indicated that a 54 kDa polypeptide increased distinctly to a very high level while a 41 kDa polypeptide decreased to a lower level in almost all the NaCl-tolerant plantlets. This observation led to the suggestion that the changes may play an adaptive role in allowing plantlets to survive under saline conditions.