Sources of Resistance to Anthracnose (Colletotrichum truncatum) in Wild Lens Species

Lentil anthracnose (Colletotrichum truncatum (Schwein.) Andrus et W.D. Moore is a potential threat in many lentil (Lens culinaris Medik.) production regions of North America. In the lentil germplasm maintained in Germany and North America, 16 lines were reported to have resistance to race Ct1, but none has resistance reported to race Ct0. The objective of this study was to examine accessions of wild Lens species for their resistance to races Ct1 and Ct0 of lentil anthracnose. Five hundred and seventy-four wild accessions of six species and control lines were screened in two replications under both field and greenhouse conditions using a 1–9 scoring scale (1, highly resistant; 2–3, resistant; 4–5, moderately resistant; 6–7, susceptible; and 8–9, highly susceptible). Indianhead and PI 320937 were resistant while Eston and Pardina were susceptible to race Ct1 as expected. However, none of the check lines were resistant to race Ct0. Among the six Lens wild species tested, accessions of Lens ervoides (Brign.) Grande had the highest level of resistance, 3–5 to race Ct1 and Ct0 followed by L. lamottei Czefr. in the field and greenhouse. Lens orientalis (Boiss.), L. odemensis L., L. nigricans (M. Bieb.) Godron and L. tomentosus L. were highly susceptible, 8–9 to race Ct0 in the greenhouse. The highest frequency of resistance, especially in L. ervoides (Brign.) Grande, was found in accessions originating from Syria and Turkey. The usefulness of these L. ervoides (Brign.) Grande accessions as sources of resistance to the more virulent race of anthracnose in a lentil breeding program is discussed.     

Sources of winter hardiness in wild lentil

Summary In high altitude areas (> c. 850 m elevation) in west Asia and north Africa, lentil (Lens culinaris) is grown as a spring crop to avoid severe winter cold. But late fall-sown lentil with winter hardiness has higher yield potential in these areas. In this study a total of 245 accessions of wild lentil, 10 of cultivated lentil and three accessions of Vicia montbretii (syn. L. montbretii) were evaluated for winter hardiness in Syria and Turkey during the 1991/92 season. The absolute minimum temperatures were-16°C in Syria and-18.9°C in Turkey and the susceptible indicators were killed at both locations showing that the cold was sufficient for screening. Although winter hardiness was assessed as percentage of survived plants in Syria and as a visual damage rating on a 1–9 scale in Turkey, there was agreement between the winter hardiness ratings with a correlation of r=–0.56, P<0.001. Accessions of L. culinaris ssp. orientalis exhibited the highest level of winter hardiness, on average; whereas accessions of L. nigricans ssp. ervoides were the most susceptible. Correlations revealed that winter hardiness was concentrated among accessions originating from high elevation areas.     

土壤水分胁迫对刺槐幼苗生长、根叶性状和生物量分配的影响

[目的]探索刺槐幼苗在干旱胁迫下的适应策略,为植被恢复过程中人工刺槐林的造林选址提供科学依据。[方法]采用盆栽控水实验法,以1年生刺槐幼苗为实验对象,设置4个水分梯度(分别为田间持水量的75%～90%,60%～75%,45%～60%,30%～45%),研究水分胁迫下刺槐幼苗的适应机制。[结果]①中度(45%～60%)和重度水分胁迫(30%～45%)明显抑制幼苗生长,其株高、地径和冠幅显著低于对照组(75%～90%),轻度水分胁迫(60%～75%)与对照组差异不显著,在实验结束时其生长状态优于对照组;②随土壤水分胁迫程度加深,刺槐幼苗根磷含量升高,比叶面积和比根长减小,叶厚度和叶组织密度增大;③中度(45%～60%)和重度水分胁迫(30%～45%)显著减少了幼苗的生物量积累,提高了幼苗的根冠比。[结论]刺槐幼苗通过将同化物质相对多的投入到防御组织的策略来适应干旱环境。重度水分胁迫严重抑制幼苗的生长,而在轻度水分胁迫下,幼苗能取得最大生长收益。     

Close Genetic Proximity Between Cultivated and Wild Bactris gasipaes Kunth Revealed by Microsatellite Markers in Western Ecuador

Bactris gasipaes Kunth (peach palm or Pejibaye) is the only domesticated palm of the Neotropics. The genetic relationships between the crop and its wild relatives are still unclear. We undertook field and laboratory work in order to describe differentiation and relationships between the wild and cultivated populations of the species in Western Ecuador, and their possible interactions. A volumetric study was undertaken on the fruits of both populations, as well as a population genetic analysis in order to clarify these relationships. Fruits from cultivated plants collected in the region of sympatry of wild and cultivated plants in North-West Ecuador showed intermediate volumes between those of reference samples for the wild and cultivated plants in allopatry. Using 8 microsatellite loci, we assessed 83 wild and cultivated individuals from Western Ecuador and cultivated plants from Amazonia and Central America as a reference for the cultivated form. We detected high polymorphism in the wild and cultivated samples and low, but significant level of genetic differentiation between wild and cultivated populations. The cultivated population in North-Western Ecuador showed close genetic proximity with the sympatric wild population, consistent with the volumetric study. These results have implications for hypotheses on evolution of this crop and for strategies of genetic conservation of the wild forms.     

Characterization of core collection of lentil germplasm for phenology, morphology, seed and straw yields

Increasing and maintaining crop residues in predominantly cereal-based rotations of the US Pacific Northwest is critical to controlling soil erosion. The core collection of lentil (Lens culinaris Medik.) germplasm comprising 287 accessions was evaluated for variation in phenological, morphological and growth parameters including seed yields and residue amounts over a two-year period under conventional tillage and no-till conditions. The objectives of this study were (i) assess lentil genetic variation in germplasm for variation in biomass production and seed yield, (ii) assess the relationship of phenological and morphological traits with biomass and seed yield and (iii) identify high biomass producing germplasm for use as parents in the breeding program. Days to flowering and days to maturity ranged from 31 to 78 and from 71 to 106 days, respectively. Time to flowering in terms of cumulative heat units was a more efficient measurement than days to flowering. Plant height and plant canopy width had a significant association with total biomass, seed yield and residue amounts. Total biomass ranged from 788–6389 kg ha^–1 under conventional tillage, while the range under no-till conditions was 1045–6195 kg ha^–1. Most of the lines with higher biomass also produced the highest seed yields and residue amounts. Overall, only one accession produced more residue than `Laird'. In the more favorable environment of 1997, six accessions exceeded the control cultivars, `Laird' and `Indianhead', for residue amounts, and seven and twenty-four accessions exceeded control cultivars, `Pardina' and `Brewer', for seed yield. Results indicated that plant height, canopy width at maturity and seed yield explained most of the variation in biomass and residue production. Large seeded germplasm consistently had a longer reproductive growth period than small seeded accessions and had 17%, 7% and 21% more biomass, seed yield and residue, respectively. Our data indicated significant variation in lentil germplasm for biomass, seed yield and residue amounts to warrant their use in the breeding program.     

西天山野果林小檗群落特征及物种多样性

[目的]调查西天山野果林小檗群落基本生态特征,为其资源保护、可持续利用和种群修复提供科学理论依据。[方法]选择典型小檗群落随机布置临时样地对其物种组成、垂直结构、种群径级结构及物种多样性进行调查,揭示小檗群落物种组成、群落结构、种群更新等方面的特点。[结果]西天山野果林小檗群落调查样地中共有种子植物19科,47属,50种,其中92.00%为双子叶植物,群落在垂直结构上可分为3层:乔木层、灌木层和草本层;灌木层小檗的重要值为196.25%,群落内各层物种多样性复杂程度总体表现为:草本层乔木层灌木层。该群落中小檗成年个体明显多于幼苗、幼树和老年个体。[结论]西天山野果林小檗群落植物区系温带属性较明显,小檗为群落的单优种与建群种。小檗种群的维持依赖于中龄个体,幼树较少,种群年龄结构呈纺锤状,属衰退型种群。     

干旱胁迫下常春藤净光合速率日变化及其影响因子分析

利用CIRAS-2型便携式光合仪对干早胁迫下3a生常春藤(Hedera nepalensis var.sinensis)叶片光合速率Pn的日动态及其主要生态生理因子进行测定分析,以阐明干早胁迫下pn的日变化特征及其午休原因,并探讨了影响常春藤Pn的主要影响因子.结果表明,常春藤Pn日动态与土壤水分及微环境因子密切相关.随着干早胁迫的加重,其pn,日均值及最大值下降显著,其中轻度、中度、重度干早胁迫下,其pn,日均值分别比对照下降15%,4700,70%;随着干早胁迫的加重,常春藤pn.日动态由"单峰"向"双峰"型变化,光合作用午休原因由气孔限制为主逐渐过渡到以非气孔限制为主.多元回归及主成分分析表明,适宜水分条件下,影响常春藤Pn的日动态因素可归纳为两类,一类以气温、相对湿度和大气CO2:浓度为主,其次是以光照强度为主;随着干早胁迫的增强,光照强度、大气CO2浓度、相对湿度等生态因子对常春藤Pn的影响越大,其中相对湿度对pn的影响最显著.     

欧洲鹅耳枥幼苗对盐胁迫的生长及生理响应

[目的]探讨欧洲鹅耳枥(Carpinus betulus)对盐胁迫的响应及其耐盐性。[方法]以两年生欧洲鹅耳枥幼苗为材料,用不同浓度NaCl(0%,0.1%,0.2%,0.3%,0.4%,0.5%)溶液处理幼苗,研究不同盐分胁迫对其幼苗生长及生理生化指标的影响。[结果](1)随着盐胁迫的加剧,欧洲鹅耳枥幼苗受到损害程度逐渐加重,相对苗高生长、相对地径生长和总干重均呈下降趋势,而根冠比则逐渐增大;(2)叶片相对含水量随着盐胁迫程度的增加而下降,且盐浓度越高,时间越久,变化幅度越大;(3)叶片叶绿素总量、SOD活性、POD活性、可溶性糖含量和可溶性蛋白含量随着盐胁迫程度的增加表现出先升高后降低的趋势;(4)随着盐浓度的增加和盐害时间的持续,幼苗叶片MDA含量、相对电导率和脯氨酸含量总体上呈增大趋势,并在胁迫末期达到最大值。[结论]欧洲鹅耳枥幼苗在0.1%~0.2%盐胁迫下能通过调节保护酶活性和渗透调节物质来减轻危害;而在0.3%胁迫下,幼苗自我调节能力受影响,0.4%~0.5%胁迫对其造成严重的损害,表明欧洲鹅耳枥耐盐性较弱,不宜在滨海地区生长。     

滨海盐碱地水盐时空变化特征及对棉花光合生产的影响

为研究滨海盐碱地土壤水盐空间分布及运移变化对棉花光合生产和产量的影响,并探讨棉田地形和土壤容重对滨海盐碱地水盐空间分布的影响方式,在位置相近区域选取海拔和容重差异较大的4块棉田,于4—10月份测定土壤0～200 cm深度水分、盐分和pH等空间分布特征,分析其对棉花光合生产和产量的影响。研究表明,轻度盐碱棉田海拔较高,在141～160 cm处形成"高容重隔层",土壤盐分和pH较低,雨季(7—8月份)土壤水分较低,生育后期(9—10月份)土壤水分明显高于中度盐碱棉田,棉花遭受盐碱胁迫较小,光合生产与水热资源吻合度高,长期处于物质积累活跃期;中度盐碱棉田较高的海拔和容重阻滞了土壤盐分和pH上升,在雨季盐碱胁迫得到解除,但棉花生育早期(4—6月份)和后期仍有明显盐碱胁迫,光合生产与光热资源丰富期吻合度较差;重度盐碱棉田海拔较低,容重差异未对水盐运移规律产生明显影响,长期处于高度盐碱胁迫之下,光合生产能力和产量水平低下。滨海盐碱地改良采用适当抬高地表高度并形成一定厚度的高容重"隔层",增强土壤蓄排水能力,是一种效果持续并有利于作物光合生产的改良措施。     

Evaluation of Paecilomyces lilacinus,chitin, and cellulose amendments in the biological control of Aspergillus flavus fungi

This study was undertaken to investigate the feasibility of using Paecilomyces lilacinus NRRL 13 866, chitin, and cellulose amendments, in order to reduce survival and prevent germination of sclerotia from Aspergillus flavus NRRL 6556, NRRL 13 048, and A. parasiticus NRRL 13 005, NRRL 13 539 buried in sandy soil in Georgia and Illinois (April–October, 1990). The number of sclerotia that germinated sporogenically in moist chambers following burial in Illinois was twice that of sclerotia buried in Georgia and varied among the four sclerotium-producing Aspergillus spp. strains. Sclerotium viability, as measured by Aspergillus spp. colony formation on potato dextrose agar, was high (>84%) for all strains and treatments (e.g. amendment, location). Even so, A. parasiticus NRRL 13 539 sclerotia were apparently more susceptible to P. lilacinus colonization than sclerotia from other strains. Treatment with Paecilomyces sp. caused a small but significant reduction in germination among sclerotia buried in Georgia.     

晋西黄土区不同退耕年限刺槐林对土壤水分和养分的影响

[目的]探讨人工刺槐林植被恢复对土壤水分和养分的影响,为半干旱黄土丘陵区植被恢复与生态建设提供理论依据。[方法]选择山西省黄河中游典型黄土丘陵沟壑区的人工刺槐林为研究对象,评估不同退耕年限刺槐林地土壤水分和养分特征。[结果]刺槐林地能够有效改善土壤水分条件,尤其在造林初期,土壤有机质和全氮平均含量显著提高,且具有明显的表聚性;刺槐林地对浅层土壤水分和养分的改善作用较大,土壤水分在40cm以上土层坑内平均水分比坑外提高了3.97%,在40cm以下土层仅提高了2.74%;土壤养分在20cm以上土层,坑内土壤有机质、全氮、全磷和全钾平均含量分别比坑外提高了6.61%,6.14%,1.55%和1.98%;在20cm以下土层,对土壤全磷和全钾无明显改善作用。[结论]刺槐林地不同程度地改善和提高了于浅层坑内土壤水分和养分状况。     

燕麦幼苗对氯化钠和氯化钾胁迫的生理响应差异

为探讨燕麦对NaCl和KCl胁迫的生理响应差异,采用水培法,研究了不同浓度NaCl和KCl胁迫对幼苗生长,活性氧代谢和渗透调节的影响。结果表明:(1)在75和150mmol/L浓度下,NaCl胁迫对燕麦幼苗的膜脂过氧化伤害和生长抑制大于KCl胁迫。NaCl胁迫下叶片中的超氧化物岐化酶(SOD),过氧化氢酶(CAT)活性及可溶性蛋白、可溶性糖和脯氨酸含量低于KCl胁迫;当浓度增大到225mmol/L时,KCl胁迫叶片中O-2.,H2O2,丙二醛(MDA),可溶性蛋白和可溶性糖含量显著大于NaCl胁迫,而SOD,抗坏血酸过氧化物酶(APX)活性及谷胱甘肽(GSH)含量则相反。(2)225mmol/L KCl和NaCl处理的植株叶片水势分别为-0.867和-1.034 MPa,渗透势分别为-1.409和-1.252 MPa,说明KCl对燕麦的更强伤害不是渗透胁迫所致;经225mmol/L KCl胁迫后,燕麦叶片中Na+含量下降至对照的36.5%,而K+含量上升为对照的1.49倍,而补充20mmol/L NaCl显著提高了225mmol/L KCl胁迫下叶片Na+的含量及SOD,APX活性,降低了K+,H2O2,O-2.和MDA含量,说明离子毒害引起的活性氧积累可能是高浓度KCl胁迫对燕麦幼苗伤害大于NaCl胁迫的重要原因。     

Effects of crop growth and soil treatments on microbial C,N, and P in dry tropical arable land

We studied the dynamics of microbial C, N, and P in soil cropped with rice (Oryza sativa) and lentils (Lens culinaris) in a dryland farming system. The crop biomass and grain yield were also studied. The microbial biomass and its N and P contents were larger under the lentil than under the rice crop. Microbial nutrients decreased as the crops grew and then increased again. Farmyard manure and NPK fertilizer applications increased the level of microbial nutrients, crop biomass, and grain yield by 35–80%, 55–85%, and 74–86%, respectively. However, these applications had no significant effect on most of the soil physicochemical properties in the short term. The microbial biomass was correlated with the crop biomass and grain yield. The calculated flux of N and P through the microbial biomass ranged from 30–45 and 10–19 kg ha^-1 year^-1, respectively. Cultivation of a cereal crop followed by a leguminous crop sustains higher levels of microbial nutrients and hence greater fertility in impoverished tropical arable soils. The soil microbial biomass appears to contribute significantly to crop productivity by releasing nutrients, and applications of manure, either alone or with fertilizers, promote this effect more strongly than the application of NPK fertilizers alone.     

Differences in the apportionment of molecular and morphological variation in North American strawberry and the consequences for genetic resource management

Variation for 24 morphological traits measured in a greenhouse environment and 36 randomly amplified polymorphic DNA (RAPD) markers was assessed among 318 wild octoploid strawberry (Fragariaspp.) genotypes from diverse habitats across the northern USA. RAPD marker frequencies and certain leaf and flower morphology traits (petiole color, leaf mass/area ratio, leaflet length and width, flower and receptacle diameter, petal width, flowers/inflorescence) were significantly different between the F. chiloensis-platypetala and F. virginiana-glauca species complexes. The proportion of variation accounted for by provenance effects was lower for the RAPD markers than for most morphological traits, especially in the F. virginiana-glauca species complex. Morphological traits of potential adaptive importance group the collection into provenances within each species-complex, and reflect the significant habitat and geographic differences across the region from which the germplasm was collected. Variation among populations within provenances was low for the molecular and most morphological traits, with a much larger amount of variability among plants within populations. Most of the variation for the presumably more selectively-neutral RAPD data was among plants within populations and populations within provenances rather than among the provenances that were recognized based on morphological traits, especially in the F. virginiana-glauca complex. Patterns of diversity for morphological traits must be considered, along with more selectively-neutral molecular characters such as RAPDs, to formulate effective sampling strategies and to properly estimate the quantity and apportionment of diversity within this germplasm.     

Evaluation of Diversity among North American Accessions of False Indigo (Amorpha fruticosa L.) for Forage and Biomass

False indigo (Amorpha fruticosa L.) is a perennial leguminous shrub native to North America. The species could potentially be used for livestock forage, biomass energy, reclamation of degraded environments, or as green manure. Future work with the species will depend upon knowledge of available accessions. Our objectives were to determine (1) the range of diversity among accessions, (2) the correlations among traits across locations, and (3) the distribution of variation among accessions. We studied 21 accessions grown at two locations and a subset of 15 accessions grown at a third location. We measured 47 morphological, agronomic, and phenological traits. All traits were influenced by accession in at least one location (p < 0.05). The mean dry matter (DM) biomass yield of accessions in August ranged from 53 to 1515 g plant⁻¹ and was correlated across locations. False indigo had a high second-year leaf concentration, averaging 660 g kg⁻¹ DM at one location in August. Forage quality of false indigo leaves was high, with average crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) concentrations in July of 205, 226, and 235 g kg⁻¹, respectively. Accession means of forage quality traits were poorly correlated across locations, indicating that it would be difficult to improve forage quality through selection. Diversity among accessions was often related to geographic origin. The two southern accessions were distinct from all other accessions, indicating that accessions from distant geographic regions will likely contribute valuable diversity to a plant breeding program.     

The Vigna angularis complex: Genetic variation and relationships revealed by RAPD analysis, and their implications for in situ conservation and domestication

The present study, using RAPD analysis, was undertaken to characterize genetic variation in three forms of V. angularis, cultivated, wild and weedy forms, and their relationships. The materials used consisted of 171 individuals (plants) or cultivars from 23 populations including 5 wild populations, 6 weedy populations, 6 cultivated populations and 6 populations with plants having wild and weedy or intermediate morphology, denoted here as complex populations. The materials used were collected on Honshu Island, Japan and seeds collected directly from the field were germinated for DNA extraction. In addition, 6 landrace accessions of V. angularis from the genebank were also analyzed. Genetic variation was highest in the wild form (H_g= 0.132; GD = 0.388), followed by the weedy form (H_g= 0.124; GD = 0.341) and the least in the cultivated form (H_g= 0.079; GD = 0.274). Intra-population genetic variation was high in the weedy and in the wild populations. However, inter-population was greater than intra-population genetic variation for all groups of populations studied in the V. angularis complex. 93% of the total diversity in the present study was exhibited by plants from complex populations and specific RAPD bands were found in these populations. Our results provide evidence that complex populations would be a logical focus for efforts to conserve the V. angularis complex in situ. Our results suggest that weedy populations are usually an ecotype of the wild form adapted to a different habitat.