Alleviation of salt stress in citrus seedlings inoculated with arbuscular mycorrhizal fungi depends on the rootstock salt tolerance

Seedlings of Cleopatra mandarin (Citrus reshni Hort. ex Tan.) and Alemow (Citrus macrophylla Wester) were inoculated with a mixture of AM fungi (Rhizophagus irregularis and Funneliformis mosseae) (+AM), or left non-inoculated (−AM). From forty-five days after fungal inoculation onwards, half of +AM or −AM plants were irrigated with nutrient solution containing 50 mM NaCl. Three months later, AM significantly increased plant growth in both Cleopatra mandarin and Alemow rootstocks. Plant growth was higher in salinized +AM plants than in non-salinized −AM plants, demonstrating that AM compensates the growth limitations imposed by salinity. Whereas AM-inoculated Cleopatra mandarin seedlings had a very good response under saline treatment, inoculation in Alemow did not alleviate the negative effect of salinity. The beneficial effect of mycorrhization is unrelated with protection against the uptake of Na or Cl and the effect of AM on these ions did not explain the different response of rootstocks. This response was related with the nutritional status since our findings confirm that AM fungi can alter host responses to salinity stress, improving more the P, K, Fe and Cu plant nutrition in Cleopatra mandarin than in Alemow plants. AM inoculation under saline treatments also increased root Mg concentration but it was higher in Cleopatra mandarin than in Alemow. This could explain why AM fungus did not completely recovered chlorophyll concentrations in Alemow and consequently it had lower photosynthesis rate than control plants. AM fungi play an essential role in citrus rootstock growth and biomass production although the intensity of this response depends on the rootstock salinity tolerance.     

Boron deficiency decreases growth and photosynthesis, and increases starch and hexoses in leaves of citrus seedlings

Seedlings of sweet orange (Citrus sinensis) were fertilized for 14 weeks with boron (B)-free or B-sufficient (2.5 or 10muM H(3)BO(3)) nutrient solution every other day. Boron deficiency resulted in an overall inhibition of plant growth, with a reduction in root, stem and leaf dry weight (DW). Boron-starved leaves showed decreased CO(2) assimilation and stomatal conductance, but increased intercellular CO(2) concentrations. Activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-glyceraldehyde-3-phosphate dehydrogenase (NADP-GAPDH) and stromal fructose-1,6-bisphosphatase (FBPase) were lower in B-deficient leaves than in controls. Contents of glucose, fructose and starch were increased in B-deficient leaves while sucrose was decreased. Boron-deficient leaves displayed higher or similar superoxide dismutase (SOD), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR) and glutathione reductase (GR) activities, while dehydroascorbate reductase (DHAR) and catalase (CAT) activities were lower. Expressed on a leaf area or protein basis, B-deficient leaves showed a higher ascorbate (AsA) concentration, but a similar AsA concentration on a DW basis. For reduced glutathione (GSH), we found a similar GSH concentration on a leaf area or protein basis and an even lower content on a DW basis. Superoxide anion (O(2)(-)) generation, malondialdehyde (MDA) concentration and electrolyte leakage were higher in B-deficient than in control leaves. In conclusion, CO(2) assimilation may be feedback-regulated by the excessive accumulation of starch and hexoses in B-deficient leaves via direct interference with chloroplast function and/or indirect repression of photosynthetic enzymes. Although B-deficient leaves remain high in activity of antioxidant enzymes, their antioxidant system as a whole does not provide sufficient protection from oxidative damage.     

Leaf gas exchange,water relations,nutrient content and growth in citrus and olive seedlings under salinity

The effects of salinity on growth, leaf nutrient content, water relations, gas exchange parameters and chlorophyll fluorescence were studied in six-month-old seedlings of citrus (Citrus limonia Osbeck) and rooted cuttings of olive (Olea europaea L. cv. Arbequina). Citrus and olive were grown in a greenhouse and watered with half strength Hoagland’s solution plus 0 or 50 mM NaCl for citrus, or plus 0 or 100 mM NaCl for olive. Salinity increased Cl⁻ and Na⁺ content in leaves and roots in both species and reduced total plant dry mass, net photosynthetic rate and stomatal conductance. Decreased growth and gas exchange was apparently due to a toxic effect of Cl⁻ and/or Na⁺ and not due to osmotic stress since both species were able to osmotically adjust to maintain pressure potential higher than in non-salinized leaves. Internal CO₂ concentration in the mesophyll was not reduced in either species. Salinity decreased leaf chlorophyll a content only in citrus.     

喷施多效唑提高麻疯树幼苗耐盐性的生理机制

研究了600 mg?L-1 PP333喷施对200 mmol?L-1 NaCl胁迫处理下麻疯树幼苗干重、含水量、叶片细胞超微结构、光合作用、叶片渗透调节能力、叶片丙二醛含量和叶片抗氧化能力的影响。结果表明：600 mg?L-1 PP333喷施处理能显著提高200 mmol?L-1 NaCl胁迫下植株的干重、根冠比和叶片含水量,同时显著降低叶片电解质外渗率（ELP）,降低叶片细胞超微结构的伤害程度,显著提高了其叶绿素含量、净光合速率、渗透调节能力、SOD酶活性和CAT酶活性,显著降低了MDA含量和POD酶活性。可见,PP333喷施能显著提高麻疯树幼苗对盐渍的适应,主要因为其提高了植株的抗氧化能力、光合作用、渗透调节能力。     

The effect of paclobutrazol on in vitro rooting and growth of GF-677 hybrid peach rootstock

This paper deals with the evaluation of the influence of paclobutrazol (N-dimethylaminosuccinamic acid) and 2-naphtoxyacetic acid on rooting and growth of GF-677 hybrid peach rootstocks. The influence of these substances on the average number of roots per plant, the average length of roots per plant and the height of plants was evaluated as well as the effect of the addition of paclobutrazol before and after media sterilisation. As the obtained results indicate, plants, which were rooted on media with paclobutrazol and without auxin had the lowest number of roots per plant. Paclobutrazol showed a statistically significant negative effect on both the length of roots and the height of plants. It canbe concluded that, for the rooting of GF-677 rootstock it is helpful to use auxin plus paclobutrazol in concentration 0.43 μM. Higher concentrations affect inhibition, mainly in height of plants 14 days after transplant to soil. A part of the results referring to the influence of PP 333 on numbers of roots was presented at the conference “Recent Advances in Plant Biotechnology, 5th International symposium in the series”, Stará Lesná, Slovakia, 7–13 September, 2003.     

Effects of constant and fluctuating soil temperature on growth,development and nutrient uptake of maize seedlings

Summary The effect of constant and fluctuating soil temperature and two soil moisture regimes on the growth, development, transpiration and nutrient uptake by maize seedlings was studied in a greenhouse investigation. The constant root temperatures were maintained at 30, 34, 35, 36, 37, and 38°C for both 250 and 750 cm of soil moisture suctions. The fluctuating root temperature, for 250 cm of soil moisture suction only, of 30–35, 30–39, 30–40, 30–45 and 30–48°C were maintained to simulate the soil temperature regime under field conditions. The constant root temperature of 35°C and fluctuating temperature between 30–40°C significantly decreased the shoot and root growth and transpiration rate. On the average, there was 1.3 and 0.7 g decrease in fresh shoot weight and 0.36 and 0.30 g in fresh root weight per degree increase in root temperature for 250 and 750 soil moisture suction, respectively. In general, the effect of high soil moisture suction on maize seedlings was more severe when at high root temperature. The shoot and root concentration of N, P, and K decreased while that of B increased with increase in root temperature. The root concentration of Zn also decreased with increase in root temperature.     

Influence of Norway spruce seedlings on the nutrient availability in mineral soil and forest floor material

A greenhouse experiment was performed to evaluate the effect of Norway spruce (Picea abies (L.) Karst.) seedlings on net nutrient availability in five different growing media containing F- or H-layer and mineral soil originating from a haplic podzol in northern Sweden. The initial total amounts of eight nutrient elements (N, K, P, Ca, Mg, Mn, Fe, Zn) and exchangeable amounts of the same elements were analyzed in pots with or without spruce seedlings. In the planted pots seedling nutrient uptake was also estimated. After 26 weeks, higher net nutrient availability with seedlings was found in 25 out of the 40 (62%) growing media and nutrient element combinations. A positive seedling effect on net nutrient availability might be explained by rhizodeposition stimulating the soil microorganism activity and accelerating the weathering of minerals or by seedling roots promoting the nutrient providing processes through changes in soil chemical and physical properties. Nitrogen availability was primarily affected by what part of the forest floor the growing medium contained although the positive response to seedling presence was apparent. The positive net availability response of P, Ca, Mg, Mn, Fe and Zn to seedling presence was on the other hand relatively strong. In the case of P, K, and Zn the growing medium composition (if the F- and H-layer was pure or mixed with mineral soil) was also an important factor for the estimated net availability. Pure F-and H-layer provided greater P- and K-availability while the availability of Zn increased when mineral soil was added. The influence of growing plants ought to be considered when soil samples are used for assessing the nutrient availability.     

Influence of the wood ant, Formica polyctena, on soil nutrient and the spruce tree growth

The effect of Formica polyctena ant nests on the distribution of soil nutrients, soil pH and the growth of Norway spruce trees was studied in the southern part of the Czech Republic. Soil nutrient content (exchangeable P, N, K and pH) and growth of mature spruce trees were measured at four distances from the nearest ant hill (0–1, 3–5, 10–50 and >200 m). Trees at all distances were visited by ants, except for those >200 m from the nearest nest. Soil pH and of P, K and NO₃ concentrations were higher near ant nests (<1 m), and pH and K at distances of 3–5 m, when compared with distances of 10–50 and >200 m from the nests, where no significant differences in these variables were detected. In contrast, tree ring analyses (1974–2004) showed that trees >200 m from the ant nests grew significantly faster than trees at other distances, followed by trees within 1 m of the nests. No growth differences were found between the growth of trees at 3–5 and 10–50 m from ant nests. We postulate that nutrient and carbohydrate removal of honeydew collected by ant‐tended aphids are slowing growth of tree. However, trees may partly compensate for this depletion by having access to a larger supply of soil nutrients near ant nests.     

铜和营养缺失对海州香薷两个种群生长、耐性及矿质营养吸收的差异影响

以来自铜矿区(CS)和非矿区(UCS)两个海州香薷种群为对象,通过室内水培实验,分析了两种群幼苗在铜及营养缺失胁迫下植物生长、铜富集及矿质营养含量的差异.结果显示,铜、低营养胁迫及其相互作用对非矿区种群生长具有明显的抑制作用,而对矿区种群的影响则远比非矿区种群小,且较低铜浓度(25μmol/L Cu)明显促进了矿区种群的生长;从耐性指数结果看,矿区种群铜耐性指数和营养胁迫耐性指数均高于非矿区种群.这表明矿区种群不仅进化为铜耐受种群,同时也进化成营养胁迫耐受种群.低营养胁迫明显促进了植物对铜的吸收和运转,如在低营养胁迫和25 μmol/L Cu复合处理下,矿区种群根铜含量约为单一铜处理的25倍,非矿区种群是单一铜处理5倍多.低营养胁迫和过量铜显著减少了非矿区种群矿质营养元素如P,Mg,K和Mn的吸收积累,而矿区种群则仍然能保持相对稳定;在铜和营养缺失复合作用下,两个种群矿质营养除Ca和部分Fe外,均显著减少,但矿区种群减少程度明显比非矿区种群小.这些结果表明,矿区种群在胁迫条件下具有保持营养相对稳定和平衡的能力,这种能力使其能在高铜污染和营养缺乏的土壤中正常生长和定居.     

Influence of soil water deficits on root growth of cotton seedlings

Summary Cotton (Gossypium hirsutum L. cv. H14) seedlings were raised in soil of differing soil water content in specially designed pots in which the roots had access to freely available water and nutrients located 2.5 cm below the base of the soil core. The time for root emergence from the soil core and the rate of root growth were measured daily from sowing to harvest. The root and shoot dry weight and leaf water potential were measured at the final harvest 16 days after sowing. As soil water content decreased, the root emerged from the soil earlier and the initial rate of root elongation was faster. In spite of the availability of freely available water, the plants in the soil at low water contents had significantly lower leaf water potentials than those in soil at high water contents. The root: shoot ratio increased as the soil water content decreased. This arose from an absolute increase in root weight, with shoot weight not being significantly affected.     

Influence of mineral nutrient availability on growth of tree seedlings from the tropical deciduous forest

The effects of different nutrient availabilities on growth and biomass partitioning in seedlings from the tropical deciduous forest in Mexico were compared. The tree species studied were Heliocarpus pallidus, a species associated with disturbed parts of the forest, and Caesalpinia eriotachys, Jacquinia pungens and Recchia mexicana, species from mature, undisturbed habitats. The tropical deciduous tree seedlings were grown in pure silica sand for 50 days inside growth chambers under four nutrient regimes; 5, 20, 100 and 200% Long Ashton nutrient solutions. Data showed contrasting responses among species to different nutrient availabilities. Except Jacquinia pungens, all species had increased growth and productivity as nutrient level increased from 5 to 100%; however, no significant differences in these parameters were detected between 100 and 200% in all species. Compared with mature forest species, pioneer species showed higher variations in biomass production, relative growth rate and net assimilation rate. In contrast to mature forest species, root/ shoot ratios in Heliocarpus pallidus were greater and thus showed higher biomass allocation to roots when nutrient supply was limited. This response suggests higher phenotypic plasticity in pioneer species. Species from mature parts of the forest (Caesalpinia eriostachys, Recchia mexicana) showed less dependency on nutrient supply than pioneer species. These responses appear to support observations from studies with temperate plants investigating growth responses to soil fertility.     

施肥对香樟幼苗生长及养分分配的影响

施肥是苗木培育的重要方式,香樟是乡土珍稀阔叶树种,苗木培育对乡土珍稀树种的保护、繁育、推广具有极其重要的作用,施肥对苗木的生长和发育具有重要的影响。因此,为了探讨香樟幼苗生长及植物体内养分分配对施肥的响应,该研究采用正交设计,设置了氮、磷、钾3因素3水平(N、P:0、3、6 g·株-1;K:0、2、4g·株-1),对盆栽香樟幼苗进行指数施肥。结果表明:(1)氮肥对香樟幼苗苗高、地径、生物量的影响最为显著,磷肥和钾肥的影响则较小;(2)氮素在香樟幼苗叶、茎、根中的分布状况主要受氮肥的影响,磷素在香樟幼苗叶、茎、根中的分布状况主要受氮肥和磷肥的影响,钾素在香樟幼苗叶、茎、根中的分布状况主要受钾肥的影响;(3)香樟幼苗的苗高生长与叶片氮含量、叶片磷含量呈显著正相关(P0.05),地径生长与茎氮含量呈显著正相关(P0.05),叶生物量与叶片氮含量、叶片磷含量呈显著正相关(P0.05),茎生物量与叶片磷含量呈显著正相关(P0.05);(4)综合分析得出,对香樟幼苗苗高、地径生长,以及枝叶生物量积累最具促进作用的施肥水平为氮肥(6 g·株-1)、磷肥(6 g·株-1)、钾肥(4 g·株-1)。     

土壤石砾含量对掌叶木幼苗生长和根系特征的影响

为探讨土壤石砾含量对珍稀濒危植物掌叶木幼苗生长和根系的影响,该研究以1个月生掌叶木幼苗为试验材料,进行5种不同土壤石砾含量[0(CK),20%,40%,60%和80%]盆栽试验,筛选最适宜掌叶木幼苗生长的土壤石砾含量。结果表明:(1)土壤石砾含量对掌叶木幼苗生长有极显著影响,其中幼苗苗高和地径相对增长率、叶面积、苗木质量指数、生物量(根、叶和全株)和根冠比均在土壤石砾含量为40%时最大。(2)土壤石砾含量对掌叶木幼苗根系形态具有极显著影响,总根长和根表面积在土壤石砾含量为40%时最大; 而根系平均直径随石砾含量增加逐渐减小,当土壤石砾含量高达80%时,根系平均直径最小。(3)土壤石砾含量对掌叶木幼苗根系拓扑结构和分形特征无显著影响,而对根系平均连接长度和分叉数有极显著影响,其中各处理根系拓扑指数(TI)、修正拓扑指数(q_a和q_b)均趋近于1,即掌叶木幼苗根系在不同土壤石砾含量中分支模式更趋近于鱼尾形分支; 根系平均连接长度随石砾含量增加先增大后减小,在土壤石砾含量40%时最大; 根系分叉数随石砾含量增加逐渐减小。(4)综合评价幼苗生长和根系形态与构型指标表明,掌叶木幼苗在40%土壤石砾含量中地下根系和地上茎叶生长状况最好。因此,土壤添加适量石砾能促进掌叶木幼苗生长,当石砾含量为40%时幼苗生长效果最好,苗木质量指数最高,最适宜掌叶木幼苗生长。     

Effect of soil K, Ca and Mg saturation and endomycorrhization on growth and nutrient uptake of sugar maple seedlings

Nutrient imbalances of declining sugar maple (Acer saccharum Marsh.) stands in southeastern Quebec have been associated with high exchangeable Mg levels in soils relative to soil K and Ca. A greenhouse experiment was set up to test the hypothesis that the equilibrium between soil exchangeable K, Ca, and Mg ions influences the growth and nutrient status of sugar maple seedlings. Also tested was whether endomycorrhization can alter nutrient acquisition under various soil exchangeable basic cations ratios. Treatments consisted of seven ratios of soil exchangeable K, Ca, and Mg making up a total base saturation of 58%, and a soil inoculation treatment with the endomycorrhizal fungus Glomus versiforme (control and inoculated), in a complete factorial design. Sugar maple seedlings were grown for 3 months in the treated soils. Plant shoot elongation rate, dry biomass and nutrient concentrations in foliage were influenced by the various ratios of soil cations. The predicted plant biomass and foliar K concentration were highest at a soil Ca saturation of 38%, a soil K saturation of 12%, and a soil Mg saturation of 8%. Potassium concentration in foliage was dependent on the level of Ca and Mg saturation in the soil when soil K saturation was close to 12%. Foliar Ca and Mg levels were more dependent on their corresponding levels in soil than foliar K. Colonization by G. versiforme did not influence seedling growth and macronutrient uptake. The results confirm that growth and nutrition of sugar maple are negatively affected by imbalances in exchangeable basic cations in soils.     

Effect of salinisation of soil on growth, water status and general nutrient accumulation in seedlings .of Delonix regia (Fabaceae)

Greenhouse experiments were conducted to assess the effect of salinisation of soil on emergence, growth, water content, proline content and mineral accumulation of seedlings of Delonix regia (Hook.) Raf. (Fabaceae). Sodium chloride (NaCl) was added to the soil and salinity was maintained at 0.3, 1.9, 3.9, 6.0 and 7.9 dS m^?1. A negative relationship between seedling emergence and salt concentration was obtained. Salinity caused reduction in water content and water potential of tissues (leaves, stems, tap roots and lateral roots) that resulted in internal water deficit to plants. Consequently, shoot and root elongation, leaf expansion and dry matter accumulation in leaves, stems, tap roots and lateral root tissues of seedlings significantly decreased in response to increasing concentration of salt. Proline content in tissues was very low. There were no effective mechanisms to control net uptake of Na on root plasma membrane and subsequently its transport to shoot tissues. Potassium content significantly decreased in tissues in response to salinisation of soil. This tree species is a moderate salt-tolerant glycophytic plant. Nitrogen and calcium content in tissues significantly decreased as soil salinity increased. Phosphors content in tissues exhibited a declining trend with increase in soil salinity. Changes in tissues and whole-plant accumulation pattern of other elements tested, as well as possible mechanisms for avoidance of Na toxicity in this tree species in response to salinisation, are discussed.     

模拟氮沉降和接种外生菌根真菌对马尾松(Pinus massoniana)幼苗营养元素的影响

量化植物地上部和地下部元素含量对于理解和预测植物养分平衡如何响应大气氮沉降的变化至关重要。通过盆栽试验研究了氮沉降增加背景下外生菌根真菌对马尾松幼苗营养元素的影响。对马尾松幼苗进行了接种两种外生菌根真菌：（彩色豆马勃（Pisolithus tinctorius,Pt）与厚环乳牛肝菌（Suillus grevillei,Sg））以及4种氮素浓度添加：0 kg N hm^-2a^-1（N0）、正常氮沉降30 kg N hm^-2a^-1（N30）、中度氮沉降60 kg N hm^-2a^-1（N60）、重度氮沉降90 kg N hm^-2a^-1（N90）,共12个处理,测定了马尾松地上部和地下部大量元素和微量元素的含量。结果表明：施氮改变了营养元素在马尾松幼苗地上部和地下部的含量,马尾松幼苗磷（P）、钙（Ca）、铁（Fe）、锰（Mn）等元素均在N60时达到临界值,而当输入的量超过了马尾松对氮的需求时,氮沉降会使马尾松营养元素含量较最适浓度时降低,地上部碳（C）随施氮浓度的升高先升高后降低,N随施氮浓度的升高而升高,根系和叶片钾（K）、Ca、镁（Mg）均随施氮浓度的升高而降低,施氮也降低了根系C及微量元素的含量。但在同一施氮浓度下,接种外生菌根真菌（EMF）后能够提高大多数元素的含量,N90时接种厚环乳牛肝菌（Sg）和彩色豆马勃（Pt）的叶片N含量与对照相比分别提高112.6%和138.6%,根系N含量分别提高73.1%、71.6%;N60时接种Sg和Pt的植株叶片P含量比不施氮未接种对照分别提高了166.3%、132.9%,根系P含量分别提高了40.8%、38.5%。EMF能够维持植物养分平衡,从而降低高施氮量对植物的影响效果。这为未来气候变化情景中氮沉降增加下接种EMF可以调节植物元素含量,从而达到更适应环境的元素平衡来促进生长提供理论依据。     

土壤养分库对缺苞箭竹叶片养分元素再分配的影响

研究了王朗自然保护区3个密度的缺苞箭竹群落的土壤养分库和叶片养分元素再分配能力的相互关系。结果表明,不同密度箭竹群落的土壤N、K贮量没有显著差异,土壤P贮量随着密度增加而显著减少（P〈0．01）,土壤Ca和Mg贮量则随着密度增加而增加。不同密度的箭竹叶片N和K的再分配能力没有显著差异,叶片P的再分配能力随着密度的增加而显著增加,Ca和Mg随着箭竹密度的增加在凋落叶中有显著积累的趋势。这表明,基于密度的箭竹叶片养分元素再分配能力与土壤养分库的大小密切相关,可能的机理过程是不同密度的箭竹在生长发育过程中改变了土壤养分库的大小,土壤养分库通过反馈机制导致箭竹叶片养分元素再分配能力的变化,体现了土壤与植被之间的互动关系。综合分析表明,P可能是限制缺苞箭竹生长发育的重要因子。     

Effect of salinisation of soil on growth, water status and general nutrient accumulation in seedlings of Delonix regia (Fabaceae)

Greenhouse experiments were conducted to assess the effect of salinisation of soil on emergence, growth, water content, proline content and mineral accumulation of seedlings of Delonix regia (Hook.) Raf. (Fabaceae). Sodium chloride (NaCl) was added to the soil and salinity was maintained at 0.3, 1.9, 3.9, 6.0 and 7.9 dS m⁻¹. A negative relationship between seedling emergence and salt concentration was obtained. Salinity caused reduction in water content and water potential of tissues (leaves, stems, tap roots and lateral roots) that resulted in internal water deficit to plants. Consequently, shoot and root elongation, leaf expansion and dry matter accumulation in leaves, stems, tap roots and lateral root tissues of seedlings significantly decreased in response to increasing concentration of salt. Proline content in tissues was very low. There were no effective mechanisms to control net uptake of Na on root plasma membrane and subsequently its transport to shoot tissues. Potassium content significantly decreased in tissues in response to salinisation of soil. This tree species is a moderate salt-tolerant glycophytic plant. Nitrogen and calcium content in tissues significantly decreased as soil salinity increased. Phosphors content in tissues exhibited a declining trend with increase in soil salinity. Changes in tissues and whole-plant accumulation pattern of other elements tested, as well as possible mechanisms for avoidance of Na toxicity in this tree species in response to salinisation, are discussed.     

高温和干旱胁迫对西红柿幼苗生长、养分含量及元素利用效率的影响

全球气候变化将增加未来高温与干旱的发生频率和强度,然而高温与干旱的交互作用对农作物生长、养分含量及其利用效率的影响还不甚清楚。因此,研究高温与干旱交互作用对农作物生理生态的影响将为准确评价农作物对未来极端气候条件的响应提供科学依据。选取全球第四大经济作物——西红柿为研究对象,在人工智能气候箱中模拟高温和干旱环境。共设置两个水分处理(正常浇水;干旱)与两个温度处理(常温-26℃/19℃(白天/夜间);高温-42℃/35℃(白天/夜间)(7d))。主要测定指标包括生物量以及生物量分配、比叶面积、养分含量(全氮、全磷)、光合元素利用效率(光合氮素利用效率、光合磷素利用效率)。研究表明,高温、干旱单独作用以及交互作用均显著降低了根、茎、叶生物量以及总生物量,并且高温干旱交互作用使总生物量降低最多。在生物量分配方面,高温单独作用显著降低了根质量分数以及根冠比,而干旱单独作用增加了根质量分数、茎质量分数以及根冠比,但降低了叶质量分数。在养分含量方面,高温单独作用导致叶片全氮、全磷含量显著降低、茎全磷含量显著增加、根全磷含量显著降低。干旱单独作用导致叶片、茎全磷含量显著降低、根全氮含量显著升高。高温与干旱交互作用对生物量分配及养分含量的影响与干旱胁迫单独作用类似。在光合元素利用效率方面,高温、干旱单独作用均降低了幼苗光合氮素利用效率、光合磷素利用效率,并且高温加剧了干旱对光合磷素利用效率的影响。因此,在未来气候变化情况下,高温与干旱交互作用可能会对农作物产生更大威胁。     

土壤涝渍对杨树和柳树苗期生长及生理性状影响的研究

研究了两种杨树无性系（ＮＬ８０１０５、ＮＬ８０３５１）和柳树在土壤涝渍条件下的生长及生理性状．结果表明,在涝渍胁迫下苗木根系数量减少,根系长度缩短,根活力下降;高生长降低;最终生物量明显减小;叶片气孔对涝渍胁迫有较强反应,叶片中硝酸还原酶（ＮＲ）活性也会受到一定影响．柳树与杨树之间存在较大差异,无论从生长还是生理性状看,杨树不如柳树耐涝．