Dynamic change of protein polypeptide of Ginkgo biloba seed during germination

The dynamic changes of protein polypeptide in endosperms of Gingkgo biloba seeds during seed germination were studied by SDS-PAGE and two-dimensional gel electrophoresis （2-DE）. The results showed that 80 kinds of protein spots in endosperms of Gingkgo biloba were clear observed in the 2-DE spectrum. Protein molecular weights were in the range of 26-52kD, and their isoelectric points were in the range of 5.8-7.8. In the course of seed germination, 13 kinds of proteins were degraded, and 13 kinds of proteins were synthesized; 7 kinds of proteins with different molecular weights and isoelectric points of 35kD/pIr.8, 31kD/pIr.8, 29kD/pIr.8, 33kD/pI6.6, 33kD/pI 6.4, 34kD/pI7.7 and 31kD/pI7.7 were identified primarily as vegetative storage proteins （VSPs）.     

水分胁迫下刺槐不同无性系生理生化反应的研究

Water stress can cause all kinds of physiological and biochemical responses on forest tree, which are indicated by changes of many physiological and biochemical indexes. Under the different drought extent of soil, the seedlings of Rob-inia pseudoacacia clones were tested. Testing indexes included water content, the ratio of bound water content and free wa-ter content ( Vα/Vs), free proline, soluble sugar, soluble protein ect. The results showed that water content decreased with the increase of soil drought, the rest indexes increased in different extent. The range of variance differed among clones. It was difficult to evaluate exactly the drought resistance of different clones depending on only physiological and biochemical index.     

Carbon unloading in roots in relation to root senescence in Cercis chinensis seedlings under drought stress

When Cercis chinensis seedlings suffered from drought treatment, net photosynthetic rates had been significantly reduced at the end of the drought treatment. Compared with the control, the activities of acid invertases in roots had increased 5 and 11 days after drought treatment. Seventeen days after drought treatment, the activities of acid invertases in roots were significantly decreased, while activities of alkaline invertases in roots had also been significantly reduced. As the moisture in culture media decreased, so the activities of sucrose synthases in leaves decreased slightly. In roots, their activities had significantly increased 5 and 11 days after drought treatment. The contents of fructose in roots reduced as the moisture in culture media decreased and 11 and 17 days after drought treatment the reduction was significant. The content of glucose in roots clearly did not change as drought stress occurred further, but was still less than that in the control seedlings. Similarly, the content of sucrose reduced as the moisture in culture media decreased. At the beginning of the drought stress, the content of sucrose was significantly higher than that in the control and afterwards there were no differences between drought-treated seedlings and the control. The gradient of the sucrose content between leaves and roots was 0.0982 mg·g–1 FW 17 days after drought treatment, while the gradient of the seedlings under normal condition was 1.3832 mg·g–1 FW. The sucrose concentration gradient reduced by 92.9%. The reduction in the sucrose content gradient under drought stress decreased the sucrose partitioning in roots. Therefore, our results support the hypothesis of ‘shared control’.     

Effects of water stress on Haloxylon ammodendron seedlings in the desert region of Heihe inland river watershed, Gansu Province, China

The water relation and leaf gas exchange of saxoul (Haloxylon Ammodendron Bge, a C4 shrub) seedlings were studied under water stress in 2001. Saxoul seedlings maintained high transpiration when the soil moisture was above 11%. The seedlings were able to take up water from soil with above 6 % soil water content, which was the threshold level of soil moisture for seedlings. The relationship between transpiration and potential evaporation was linear for well-watered seedlings. The decrease of soil water availability led to different degrees of down-regulation of stomatal conductance, leaf transpiration and net CO2 assimilation rate. The stomata played a relatively small part in determining the net CO2 assimilation rate for the same seedling. The relationship between net CO2 assimilation rate and transpiration was linear diurnally, and reduction scale of leaf transpiration was much bigger than that of net CO2 assimilation rate by waters tress treatments, therefore intrinsic water-use-efficiency increased. High evaporative demand increased the leaf transpiration but inhibited net CO2 assimilation rate.Because of the effect of VPD on transpiration in this region, the transpiration of well-watered and mild water stress seedlings becomes responsive to change in stomatal conductance over a wider range.     

Effects of drought stress on the photosynthetic physiological parameters of Populus 3 euramericana ‘‘Neva'

Populus 9 euramericana ‘‘Neva' is the main poplar species in China, where drought stress is becoming extremely urgent. We carried out this research to study the effects of drought stress on the photosynthesis of Populus 9 euramericana ‘‘Neva'. Drought stress was induced by 58–62%(light), 48–52%(moderate), and 38–42%(severe) relative soil moisture content(RSMC). The effects of drought stress on photosynthetic rate, chlorophyll fluorescence parameters, and other related physiological parameters were investigated during treatment. Net photosynthetic rate(PN), and stomatal conductance decreased significantly and intercellular CO_2 concentration initially increased and then declined, whereas the stomatal limitation factors showed opposite trends in the light under moderate drought stress. Photosystem II(PSII) maximum photochemical efficiency, actual photochemical efficiency,and photochemical quenching decreased gradually under drought stress, whereas nonphotochemical quenching initially increased and then declined. Superoxide dismutase,peroxidase, and catalase activities initially increased and then decreased as RSMC was reduced, whereas malondialdehyde(MDA) content and relative electric conductivity(REC) increased gradually. These results suggest that stomatal factors accounted for the decline in PNunder light and moderate drought stress, whereas leaf PNdecreased mainly due to non-stomatal factors under severe drought stress. PSII was damaged; thus, photosynthetic electron transfer was restricted, indicating that heat dissipation is important for the light protection mechanism of plants.Antioxidant enzymes increased at the beginning of treatment, and the increased MDA and REC led to cell membrane damage. These results suggest that poplar seedlings stabilized their photosynthetic apparatus by reducing the light trapping ability under light and moderate drought stress conditions. This helped dissipate heat and enhance antioxidant enzyme activity. Stomatal factors accounted for the decline in P_N, whereas damage to PSII and antioxidant enzymes under severe drought stress suggested that the decline in P_N was caused by non-stomatal restrictive factors.     

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.     

Expression of a carrot 36 kD antifreeze protein gene improves cold stress tolerance in transgenic tobacco

Antifreeze proteins （AFPs） enable organisms to survive under cold conditions, and have great potential in improving cold tolerance of cold-sensitive plants, In order to determine whether expression of the carrot 36 kD antifreeze protein gene confers improved cold-resistant properties to plant tissues, we tried to obtain transgenic tobacco plants which expressed the antifreeze protein. Cold, salt, and drought induced promoter Prd29A was cloned using PCR from Arabidopsis. Two plant expression vectors based on pBI121 were constructed with CaMV35S：AFP and Prd29A：AFP. Tobacco plantlets were transformed by Agrobacterium-medicated transformation. PCR and Southern blotting demonstrated that the carrot 36 kD afp gene was successfully integrated into the genomes of transformed plantlets. The expression of the afp gene in transgenic plants led to improved tolerance to cold stress. However, the use of the strong constitutive 35S cauliflower mosaic virus （CaMV） promoter to drive expression of afp also resulted in growth retardation under normal growing conditions. In contrast, the expression of afp driven by the stress-inducible Prd29A promoter from Arabidopsis gave rise to minimal effects on plant growth while providing an increased tolerance to cold stress condition （2℃）. The results demonstrated the prospect of using Prd29A-AFP transgenic plants in cold-stressed conditions that will in turn benefit agriculture.     

Drought stress,mercuric chloride,and b-mercaptoethanol effects on hydraulic characteristics of three cultivars of wolfberry(Lycium chinense)

In order to further understand the effects of drought stress on hydraulic characteristics and the relationship between hydraulic conductivity and aquaporins or water channels of root systems of three wolfberry cultivars(Lycium chinense Mill.),hydraulic conductivity of 2-yearold pot-grown seedlings was measured under drought stress,rewatering,and treatment with exogenous mercuric chloride and β-mercaptoethanol.Under moderate and severe drought stress levels,the most significant decrease of hydraulic conductivity was 37.3% and 24.0%,respectively,in the 'Ningqi 5' cultivar compared with the nonstressed control.After rewatering,the rate of recovery in specific conductivity was most rapid in the 'Mengqi 1'cultivar,at 0.058 and 0.072 kg MPa~(-1) m~(-2) s~(-1) h~(-1) under moderate and severe drought stress levels,respectively.The 'Mengqi 1' cultivar had the highest recovery degree of hydraulic conductivity under two concentrations of β-ME(500 or 1000 μmol L~(-1)),reaching 82.4% and 88.5%,respectively,of the initial conductivity.The adaptive capacity of hydraulic conductivity in the 'Ningqi 5' cultivar was weaker than in the 'Ningqi 1' and 'Mengqi 1'cultivars under drought stress.The recovery capacity of hydraulic conductivity in 'Mengqi 1' cultivar was stronger than the 'Ningqi 1' and 'Ningqi 5' cultivars after rewatering.Aquaporins of the 'Ningqi 1' cultivar root systems had the highest binding affinity with mercuric chloride,which was the most likely cause in the decrease in hydraulic conductivity,whereas aquaporins of 'Mengqi 1'root systems had the weakest binding affinity.The inhibitory effect of mercuric chloride was readily eliminated byβ-mercaptoethanol in the 'Mengqi 1' cultivar.The hydraulic characteristics of this cultivar were more sensitive to drought,mercuric chloride and β-mercaptoethanol than the other cultivars.     

Adaptive responses of<Emphasis Type="Italic">Acer ginnala,Pyrus ussuriensis and Prunus davidiana</Emphasis> seedlings to soil moisture stress

One-year-old seedlings of Amur maple (Acer ginnala Maxim), Ussurian pear (Pyrus ussuriensis Maxim) and David peach (Prunus davidiana Carr) were planted in pots in greenhouse and treated with four different soil moisture contents (75.0%,61.1%, 46.4% and 35.4%). The results showed that net photosynthesis rate (NPR), transpiration rate (TR) and stomatal conductance (Sc) of seedlings of the three species decreased with the decease of soil moisture content, and Amur maple seedlings had the greatest change in those physiological indices, followed by Ussurian pear, David peach. Amur maple and Ussurian pear seedlings also presented a decrease tendency in water use efficiency (WUE) under lower soil moisture content, whereas this was reversed for David peach. Under water stress the biomass allocation to seedling root had a significant increase for all the experimental species. As to root/shoot ratio, Amur maple seedlings had the biggest increase, while David peach had the smaliest increase. The leaf plasticity of Amur maple seedlings was greater, the leaf size and total leaf area decreased significantly as the stress was intensified. No significant change of leaf size and total leaf area was found in seedlings of Ussurian pear and David peach. It was concluded that Amur maple was more tolerant to soil moisture stress in comparison with David peach and Ussurian pear.     

Drought stress tolerance analysis of Populus ussuriensis clones with different ploidies

The selection of drought-tolerant plants is an important aspect of plant breeding.We studied physiological and biochemical mechanisms of different ploidies of Populus ussuriensis Kom.that relate to drought stress tolerance.We used a 5%(v/v)polyethylene glycol(PEG-6000)solution to simulate drought stress.We recorded leaf phenotypes including color,dry area and curl degree.We evaluated sequential variations in some drought stress tolerance-related physiological and biochemical indices and compared these among diploid clones(CK),triploid clones(T12)and tetraploid clones(F20).T12 leaves exhibited slightly more drought stress damage than CK and F20 leaves.CK leaves suffered the most severe drought stress damage.The physiological and biochemical indices of the different ploidies differed significantly 12 days after drought stress treatment.The activities of superoxide dismutase,peroxidase,catalase and proline in the triploid(T12)leaves were the highest.The relative electric conductivity and malondialdehyde content of T12 leaves were the lowest.The index values of F20 were between those ofthe diploid and triploid.In consideration of these results,the drought resistance of the three different ploidies of P.ussuriensis can be ranked as T12>F20>CK.We speculate that the gene expression patterns of polyploid clones of poplar will change after genome doubling and that some of the drought stress tolerance-related physiological and biochemical indices will be improved,resulting in greater drought tolerance of polyploid clones.     

氮素高效基因型杉木无性系的选择研究

为筛选适应退化地生长的杉木无性系 ,通过N素胁迫进行N素高效基因型杉木无性系的选择研究 ,结果表明 :不同杉木无性系的N素利用效率存在差异。随N素胁迫加剧 ,杉木无性系NR活力及光饱和点下降 ,CO2 补偿点增加 ,不同杉木无性系对N素胁迫的反应日趋明显 ,根据不同无性系在胁迫条件下的反应 ,把供试无性系分成 3类 :耐N肥性强、耐N肥性弱及耐N肥性一般无性系 ,其中 16 3号和 30 1号无性系是具有较高N素利用效率的省肥高产无性系 ,在肥力较低的林地上能获得较高的产量     

林冠对降雨截留的半理论模型

在林冠对降雨截留过程的研究中,将理论模型的考虑方法和经验模型的模拟方法结合起来,提出一种新的半理论模型。这个半理论模型既具有理论模型把过程与机理紧密联系的优点,又具有经验模型计算相对简单的长处,新模型与实验数据很好地符合,也和理论模型的结果一致。     

心理物理学方法在国外森林景观评价中的应用

本文系统介绍了常用于国外森林景观评价中的几种心理物理学方法 ,从数学和经验两方面介绍了SBE法和LCJ法的异同点 ,综述了国外针对森林景观评价过程中涉及的一些基本问题所进行的研究。最后总结了 30年来心理物理学方法在森林景观评价中的应用实践及由此摸索出来的各种森林景观元素与美景度之间的关系 ,并分析了森林景观评价的发展趋势和存在的不足。     

太行山低山丘陵区苹果生姜间作系统综合效应研究

本文对太行山低山丘陵区苹果生姜间作系统的生态效应，生理效应，产量效应及土地利用率进行研究，结果表明，对比单作姜园平均可使生姜冠层叶温降低２．５℃，空气相对湿度提高１６％，对比清耕果园，可使０－５０cm土层土壤含水量提高８．５％，可使生姜叶片叶绿素含量提高１６．６％，苹果光合速率提高１０．０％，生姜和苹果单位产量分别提高３．１％和２．０％，间作系统土地当量值可达１．６４，总体土地利用率可提高６４％。     

温度对杉木中龄林针叶光合生理生态的影响

采用活体测定方法 ,在大气CO2 浓度 (35 0± 10 ) μL·L- 1 、70 %± 5 %相对湿度和一定光合有效辐射通量密度条件下 ,测定了 18a生杉木 (Cunninghamialanceolata(Lamb .)Hook .)中龄林针叶净光合速率 (Pn)、气孔导度 (gs)、蒸腾速率 (E)和暗呼吸 (Rd)等光合生理生态指标对温度的响应。结果表明 ,杉木中龄林针叶光合生理生态指标对温度的变化非常敏感。Pn对温度的响应呈抛物线型 ,不同季节Pn的最适温度不同 ,在生长盛期 (5月下旬 )和后期 (10月中旬 )为 2 5℃左右 ,在生长中期 30℃左右 ,但生长盛期当年生针叶例外 ,其Pn最适温度仅 2 2℃～ 2 3℃。Pn的最适温度与测定前 5d平均最高气温更接近。gs 和E对温度的响应与Pn相似 ,但gs 达最大值的温度比Pn低。在试验条件下温度对Pn的影响可能主要由于非气孔因素引起。温度对gs的影响可能源于叶面 -大气水汽压差 (VPD)的变化和光合作用引起的胞间CO2 浓度的改变。温度对E的影响与gs 和VPD的变化密不可分。暗呼吸随温度增加呈指数增加 ,但由于生理活性和所处光环境的差异 ,当年生针叶Rd明显高于 1a生和 2a生老叶。杉木针叶光合生理生态对温度变化的长期响应与适应 ,还有待于进一步的研究。     

落叶松-杨栅锈菌遗传分化的RAPD分析

用随机扩增多态性ＤＮＡ（Ｒａｎｄｏｍ ａｍｐｌｉｆｉｅｄ ｐｏｌｙｍｏｒｐｈｉｃ ＤＮＡ,ＲＡＰＤ）技术对来自陕西及青海的７个地区的１３个落叶松－杨栅锈菌（Ｍｅｌａｍｐｓｏｒａ ｌａｒｉｃｉ－ｐｏｐｕｌｉｎａａ Ｋｌｅｂ．）的分离物进行了基因组ＤＮＡ多态性分析。１３个１０－核苷酸随机引物（Ｏｐｅｒｏｎ公司）对１３个菌株共扩增出８１条ＲＡＰＤ带,其中６９个ＤＮＡ片断呈现多态性,占总扩增片断的８５．２％。供试菌株的相似系数在０．６０８～１．０００之间,各菌株之间的差异在０～３３．１％之间,并建立了聚类树状图。１３个菌株在相似性７６．１％时被分为４个类群：Ⅰ组包括秦岭宁陕火地塘Ｃ的２个分离物,Ⅱ组为火地塘Ｂ的１个分离物;Ⅲ组为青海西宁、互助,陕西太白宝太路、宝鸡天台山、周至厚畛子（ＨＺａ）等５个地区的８个分离物;第Ⅳ     

轮伐期对杉木人工林地力维护的影响

通过对全国杉木中心产区不同发育阶段杉木人工林生长及生物量的调查,研究轮伐期对杉木人工林生物量及养分分布规律的影响,结果表明：不同轮伐期经营的杉木林林分生物量及其养分分配规律存在差异,随年龄阶段的提高,杉木枝、叶、根、边材及林冠所占比例逐年下降,干、皮和心材比例逐年增加,边材／心材及林冠／树干比例下降,轮伐期越短,每采伐单位杉木干物质所带走的养分越多,对地力的消耗越严重;同时短轮伐期还造成采伐、炼山     

酸铝对杉木磷吸收和代谢的影响

用＾３２Ｐ示踪原子法通过水培试验研究了酸性条件下铝对１年生杉木的根和叶磷吸收和代谢的影响。结果表明,在ｐＨ＝３时,用酸铝处理根和叶后,根中＾３２Ｐ－无机磷增加到对照的１９５％,叶片＾３２Ｐ－无机磷转运指数由４３．０降低到２０．０。根的Ｐ总含量中的各＾３２Ｐ－化俣物比例发生较大变化,无机磷增加到对照的１７５％,有机化合物,脂类化合物,ＤＮＡ,ＲＮＡ分别减少到对照的５５％,４２％,３６％,４０％;叶中     

人工马尾松复层混交林林分结构规律的研究

From the analysis and simulated study on the stand structures of present the multi-stories mixed uneven-agedPinus massoniana planted forests in Fujian, the correlationships between stand diameter distribution structure, stand stockdistribution structure, tree height and DBH were obtained. Several proposals for the rational management and structure ad-justment of the present forests were put forward.     

水双相法分离泡桐幼苗根细胞质膜的研究

通过对草本植物水双相法分离细胞质膜技术的改进，建立起木本植物泡桐根细胞质膜的分离纯化方法。其改进主要有：在匀浆介质中添加了抗坏血酸，加大了聚乙烯聚吡咯烷酮的用量，由草本植物一般用量０．０５％－０．１％增至０．６％；对第１次双相分离后下相液中剩余的质膜进行了再回收。通过对质膜和细胞器各项标记酶指标的测定，确定了６．３％，葡聚糖（Dextran)T-500和６．３％的聚乙二醇（ＰＥＧ）４０００为主组成的两相系统分离的根细胞质膜具有较高的收率和纯度。该方法的建立为细胞和分子水平上研究木根系对离子吸收机理与生长发育的关系打下了基础。