Morphological and biochemical variation in Sardinian populations ofMedicago polymorpha L. suitable for rainfed Mediterranean conditions

Summary Forty five accessions of Sardinian germplasm ofMedicago polymorpha L., derived from a wide range of climatic and edaphic conditions, were evaluated to identify useful genetic resources for the development of cultivars for rainfed Mediterranean conditions. The accessions were assessed for variation in morphological, agronomic and biochemical traits. Considerable variation was found between populations indicating the potential for selection.Work supported by the Italian Ministry of Agriculture and Forestry (MAF), Special Project Foraggicoltura Prativa, subproject Miglioramento Genetico.     

Morphological characterization of kale populations from northwestern Spain

Crops belonging to the genus Brassicaare widely grown in Galicia (northwesternSpain). Kales (Brassica oleracea L.convar. acephala (DC.) Alef.) are oneof the most important Brassica cropsin this region where landraces aretraditionally grown by farmers on smallplots for either human or animal food.Fifteen kale populations from northwesternSpain were evaluated in two locations andtwo planting dates (early and late). Theobjectives were i) to study theirmorphological diversity, ii) to determinetheir relationships, and iii) to evaluatetheir morphological and agronomiccharacteristics that could be incorporatedto breeding programs in the future.Significant differences were found amongpopulations for all traits while genotype ×environment interaction was not significantfor most of them. Cluster and principalcomponent analysis were performed todetermine relationships among landraces andto obtain information on the usefulness ofthe characters for the definition ofgroups. The phenogram showed five groups,two groups including most of thepopulations and three small independentgroups. Groups of landraces were associatedwith the geographical origin and withmorphological differences amongpopulations, mainly with the length oftheir vegetative phase: north and earlypopulations (cluster A) and south and latepopulations (cluster B). Morphologicaldiversity was higher in coastal populationsthan in inland populations. As conclusion,the populations evaluated in this workdisplay a wide diversity of traits whichenable us to select and combine someinteresting landraces for important traitsin order to obtain improved varieties.     

Morphological variation in Astragalus hamosus L. and Coronilla scorpioides L. populations of Tunisia

Morphological variation between Astragalus hamosus and Coronillascorpioides populations was studied using local germoplasm collected in northern and central Tunisia. Twenty-one morphological traits were recorded and data were analysed using complementary statistical analysis. Considerable variation based on morphological and agronomical traits was found between populations and for both species. Pod and peduncle lengths as well as flowers number were the most discriminant variables between populations. Differences were also found for variables like seed number per pod, seed yield and dry matter production. Significant correlations were found between plant traits and the environmental parameters of the origin sites. This study revealed enough variation among populations to initiate a selection programme for pasture improvement in arid and semi-arid areas of Tunisia, where the two species are well adapted. This revised version was published online in July 2006 with corrections to the Cover Date.     

Variation and covariation in Vicia faba L. populations of Mediterranean origins

Summary Variation and covariation in 15 Vicia faba L. ssp. major populations from Italy. Greece and Egypt were analyzed. Ten quantitative morphobiological characters of agronomical and nutritional interest were observed. Differences among countries of origin were highly significant for all characters except for lowest podded node. Phenotypic distances among populations, both within and among origins, estimated on canonical variates evidenced that the Egyptian populations from a distinct group and that a relevant degree of similarity exists among the Greek and the Italian meterial. The covariation structure within populations, which was studied by means of factor analysis, was comparatively simpler in the Egyptian material than in that form the other two Mediterranean countries. The differences evidenced can be attributed to different gene associations between characters and suggest the possibility of obtaining, through recombination, genotypes agronomically more favorable.Research work supported by C.N.R., Italy, special grant. Sub-Project 1, Paper No. 299.     

Climatic adaptation in subterranean clover populations

Summary Long-term persistence and, hence, agronomic success as a pasture of the annual species subterranean clover depend primarily on seed yield and seed survival over seasons. In natural populations, plant characteristics influencing seed setting and formation of seed reserves in the soil are expected to be adjusted to the prevailing environmental conditions of the sites of origin. Knowledge on plant/environment relationships may provide information on adaptive strategies of persistence, and guidelines for selecting adapted varieties to specific conditions. On pure lines from a number of populations such relationships were assessed for flowering time, seed yield, burr fertility, individual seed weight, initial hardseededness, and rate of hardseededness breakdown over summer. Flowering time decreased on decreasing annual rainfall, i.e., on shortening the growing season, as adaptive response to the need of producing adequate seed before the onset of the dry season. Individual seed weight decreased on decreasing rainfall, and increasing temperatures. Hard-seed maintenance over summer was higher in populations from hot and dry environments, where the marked effect of temperature on hardseededness breakdown exerts a strong selective pressure. Within-population variation, assessed on flowering time, was particularly wide, with early genotypes occurring even in populations from long-season environments. The adaptive relevance of maintaining high levels of within-population polymorphism to cope with unpredictable climatic fluctuations is discussed. Number of constituent lines as a measure of the population structure, and intra-population variation were both influenced by altitude and rainfall, tending to decrease as the climatic selective pressure becomes severe, under both low-rainfall, hot conditions and high-elevation, cold-prone environments.     

Morphological variation within collections of Moroccan almond clones and Mediterranean and North American cultivars

Summary Cultivated almonds (Prunus dulcis (Miller) D.A. Webb) in Morocco are still propagated from seeds by farmers to overcome transplant failure of grafted trees. Almond collections in southern Morocco conducted since 1975 have resulted in the selection of clones planted at 3 experimental stations. Principal component analysis (PCA) was used to compare kernel, nut, leaf, and growth habit characteristics among 67 selected Moroccan clones and 14 introduced cultivars. Clustering of clones from similar countries and collection areas would suggest the existence of different almond populations. The Moroccan clones did not cluster separately from the foreign cultivars. Three Moroccan clones had exceptionally large nuts and kernels while 7 selections had high yield potential due to high spur density. Moroccan selections tended to be characterized by small leaves in comparison to foreign cultivars. No evidence was found to suggest the existence of separate populations within the Moroccan almond germplasm.     

棉花表型性状基因的SSR标记定位

本文以两个陆地棉多标记基因系T582和T586,以及杂交获得的F_1、F_2及F_3代作为试验材料,利用11对SSR引物对F_2群体的120个单株的DNA样品进行多态性分析,并利用F_2和F_3群体对F_2群体对应单株的13个表型性状进行基因型的判定,结果得到了3个与表型性状基因连锁的SSR标记,分别是红茎基因(R_1)与J178连锁、遗传距离为24.9cM,簇生铃基因(CL_1)与J236连锁,遗传距离为46.0cM,茸毛基因(T_1)与J252连锁,遗传距离为28.5cM,其中R_1、CL_1、J178和J236在同一连锁群上。红茎和植株茸毛是具有抗虫性能的形态性状,用SSR标记这些性状将有助于提高育种家的育种效率。     

Effects of Grazing on Bituminaria bituminosa (L) Stirton: A Potential Forage Crop in Mediterranean Grasslands

Plant traits of Bituminaria bituminosa, as affected by different intensities of cattle grazing, were studied in a Mediterranean grassland in Israel. B. bituminosa is a widespread Mediterranean perennial legume species that may potentially serve as a fodder crop in Mediterranean grasslands. The aims of the present study were: (i) to evaluate the responses of B. bituminosa to different cattle grazing intensities; (ii) to study functional traits associated with grazing tolerance; and (iii) to evaluate its potential as an alternative forage crop in the region. A total of 100 B. bituminosa plants were monitored in field conditions. During the growing season each individual was sampled five times and the following plant traits were monitored each time: (i) aboveground biomass production, (ii) plant height, (iii) specific leaf area (SLA), (iv) number of flowers, (v) seed mass and size, (vi) tannin concentration in leaves, (vii) total nitrogen in leaves, (viii) fibre concentration in leaves (Neutral Detergent Fiber), and (ix) in vitro dry matter digestibility. The results showed that grazing intensity and history of grazing affected B. bituminosa performance. Plant biomass, height, and flower and seed production were all reduced when plants were exposed to cattle grazing. However, under moderate grazing intensities, its plant cover remained relatively stable indicating a potential tolerance under this stocking rate. The nutritious characteristics of B. bituminosa leaves were good, and the condensed tannins concentration found indicated favourable conditions for digestion. Moreover, the in vitro digestibility studies indicated relatively high values (46–51 %) of digestion. B. bituminosa may be considered as a potential crop for cattle feeding in Mediterranean grasslands. Growing this plant in dense stands in rotational paddocks may provide alternative sources of natural fodder protein, reducing the potential costs of artificial feed supplements.     

Variation between and within Trifolium repens L. populations collected from sown swards in Uruguay

Nineteen Trifolium repens L. (white clover) populations were collected in different parts of Uruguay (where conditions are marginal for the species) from swards sown 2–15 years earlier. Twenty five genotypes of each population were grown as spaced plants on a single site. Leaflet length and width, petiole length, plant height, plant diameter and internode length were recorded. In a second experiment, ten of the populations were studied in a similar way. Large genetic correlations were obtained among leaflet length, leaflet width, petiole length and plant height as one group, and among major plant diameter, minor plant diameter and internode length as another group, in both experiments. Collection site characteristics that tended to result in relatively short, small-leaved plants were: the sowing of cv. Bayucuá or Santa Fé (rather than Zapicán orYi); a relatively old sward; relatively high available soil P; overgrazing; and dry conditions. There was an indication that, in some respects, there was less variation within a population in older than in younger swards. Overall and within populations heritabilities were relatively high for leaflet length, leaflet width and petiole length and relatively low for plant diameter, with plant height intermediate. Genotypes from populations (such as that from Romero) that survived for 15 years in unfavourable conditions could be useful in a plant breeding programme. Selection for rather smaller-leaved types might enhance persistence. This revised version was published online in July 2006 with corrections to the Cover Date.     

Artificially induced polyploidization in Humulus lupulus L. and its effect on morphological and chemical traits

Chemically induced polyploids were obtained by the colchicine treatment of shoot tips of Humulus lupulus L. ‘Sybilla’. Flow cytometry revealed that most of the treatments resulted in the production of tetraploids. The highest number of tetraploids was obtained when explants were immersed in 0.05% colchicine for 48 h. A field experiment was conducted to compare diploid and tetraploid plants and assess the effect of genome polyploidization on the morphological and chemical characteristics. Tetraploids showed significant differences in relation to diploids. They had thinner and shorter shoots. The influence of chromosome doubling was also reflected in the length, width and area of leaves. The length of female flowers in the tetraploids was significantly shorter than that observed in diploids. Tetraploids produced a diverse number of lupuline glands that were almost twice as large as those observed in diploids. The most distinct effect of genome polyploidization was a significant increase in the weight of cones and spindles. Contents of major chemical constituents of hop cones was little affected by ploidy level. Total essential oils were significantly lower than those in diploids. However there was a significant increase in the proportion of humulene, caryophyllene and farnesene, oils desired by the brewing industry.     

Morphological and RAPD analysis of poplar trees of anther culture origin

Our objectives were to improve the rate of haploid plant regeneration through increasing the rate of callus initiation on the anthers and sustaining shoot regeneration frequency, and to analyze the field population of anther culture origin by morphological and molecular methods. Regarding the callus initiation, the most responsive clones were ‘N-90’(59%) in P. nigra and ‘D-29’ (75%) in P. deltoides. The rate of shoot regeneration and number of shoots/calli ranged from 4%–79% and 1–9, respectively. From the 208 rooted plants 8 haploid, 179 diploid, 4 tetraploid and 17 aneuploid plants were found. In the field population, the haploid plants could be easily identified by their retarded development and morphological characteristics (size and shape of the leaves, strong branching, etc). Several diploid plants showed depressed developmental and morphological traits similar to the haploid ones. Three traits (growth rate, leaf blade length and shape of leaf base) of the 6 different morphological characteristics measured were in correlation with the ploidy level within the poplar field population. Six primers of the 48 primers tested were able to detect polymorphism among the field plants. This revised version was published online in July 2006 with corrections to the Cover Date.     

Using the CERES-Maize model in a semi-arid Mediterranean environment. Evaluation of model performance

The CERES-Maize model was tested in a semi-arid Mediterranean environment during a period of 2 years under three different soil moisture conditions (well-watered and two limited irrigation regimes). In well-watered plots, growth and yield were adequately simulated by the model (differences between simulated values and observations were less than 10%). Results suggest that the absence of air humidity among the model inputs does not limit the CERES-Maize performance, even under dry-air conditions. On the contrary, under mild soil water shortage, CERES-Maize underestimated the leaf area index (LAI) (up to 26% for maximum LAI), above-ground biomass (up to 23%) and grain yield (up to 15%). Mismatches between observations and predictions increased with water stress level (by up to 46, 29 and 23% for maximum LAI, biomass and grain yield, respectively). It is suggested that the functions describing leaf growth and senescence and those calculating the soil water deficit functions should be modified to adapt CERES-Maize to Mediterranean environments.     

Adaptation and yielding ability of castor plant (Ricinus communis L.) genotypes in a Mediterranean climate

Successful castor (Ricinus communis L.) cropping in Greece depends on the yielding ability and yield stability of the cultivars (hybrids or inbreds) as well as the reliability of production systems. The adaptation and yielding ability of 19 modern castor oil genotypes were studied for 3 years in two sites of Northern Greece. Genotypes combining high seed and oil yield and desirable morphological characteristics were tested for 2 or 3 years, whereas the rest were tested for 1 year only. The growing period in both locations was long enough for ripening the first raceme and a number of secondary racemes depending on the genotypes. The plant height was dependent mainly on the genotypes but also was affected by the site and the year of the experimentation and ranged from 79 to 278 cm. The seed yield varied between 2.5 and 5.0 Mg ha⁻¹, values that are among the highest reported in the literature. The seed yield was higher in the site where plants produced and ripened more secondary racemes. The seed oil content was dependent mainly on the genotype and ranged from 44.5 to 54.2%. The oil yield followed the changes in seed yield. The variation in seed yield between years was low and in most genotypes less than 20%. Results indicate that the castor oil crop was satisfactorily adapted in the area.     

Morphological Traits Associated with Lodging Resistance of Spring Wheat (Triticum aestivum L.)

Throughout the world, lodging in cereals causes great losses in yield each year. A two year field study was conducted to determine the relationship of morphological traits to lodging resistance in spring wheat ( Triticum aestivum L.) breeding lines and to find easily measurable traits related to lodging resistance. A set of 15 breeding lines, representing a wide range of combinations of plant height and lodging resistance, was evaluated.
During the first year, 29 morphological traits were measured at two growth stages and correlated with the lodging score. Higher correlations were found for traits measured at anthesis (DC 65) than for traits measured at maturity (DC 92); most of the fresh weight traits correlated better to lodging resistance than did the corresponding dry matter parameters. During the second year the six traits of plant height, stem length, stem diameter, ear weight, stem weight and stem weight per cm were measured at anthesis and correlated with the lodging score.
From the pooled data of four experiments, significant correlations between the lodging score and single morphological traits were found for stem diameter and stem weight per cm. Thicker stems and heavier stems (mg per cm) were indicative for better lodging resistance. Stem diameter and stem weight cm⁻¹ explained 48.5 % and 49.7 %, respectively, of the phenotypic variation in lodging resistance. Multiple linear regression equations indicated that 77.2 % of the variation in lodging resistance was based on stem weight cm⁻¹ and on the weight of the ear.     

冠菌素对早稻和水稻幼苗形态及生理指标的影响

用不同浓度的冠菌素对旱稻297和水稻越富进行浸种处理。研究冠菌素对旱稻和水稻幼苗的形态指标（干物重、株高、根长、根表面积、根系体积及侧根发生量）和生理指标（根系活力和叶绿素含量）的影响。结果表明：高浓度（≥10^-5mol／L）的冠菌素处理后旱稻和水稻幼苗的株高、根系生长、根系活力、干物质积累量及叶绿素含量均明显降低：而较低浓度（10^-8-10^-7mol／L）的冠菌素处理却促进了旱稻幼苗根系生长。提高了根系活力。促进了干物质的积累,对水稻幼苗根系生长（侧根发生）也有一定的促进作用：初步认为用低浓度的冠菌素浸种培育健壮幼苗是可行的。     

Response of giant reed (Arundo donax L.) to nitrogen fertilization and soil water availability in semi-arid Mediterranean environment

The aim of the present work was to evaluate the effect of soil water availability and nitrogen fertilization on yield, water use efficiency and agronomic nitrogen use efficiency of giant reed (Arundo donax L.) over four-year field experiment.After the year of establishment, three levels for each factor were studied in the following three years: I₀ (irrigation only during the year of establishment), I₁ (50% ETm restitution) and I₂ (100% ETm restitution); N₀ (0 kg N ha⁻¹), N₁ (60 kg N ha⁻¹) and N₂ (120 kg N ha⁻¹).Irrigation and nitrogen effects resulted significant for stem height and leaf area index (LAI) before senescence, while no differences were observed for stem density and LAI at harvest.Aboveground biomass dry matter (DM) yield increased following the year of establishment in all irrigation and N fertilization treatments. It was always the highest in I₂N₂ (18.3, 28.8 and 28.9 t DM ha⁻¹ at second, third and fourth year growing season, respectively). The lowest values were observed in I₀N₀ (11.0, 13.4 and 12.9 t DM ha⁻¹, respectively).Water use efficiency (WUE) was significantly higher in the most stressed irrigation treatment (I₀), decreasing in the intermediate (I₁) and further in the highest irrigation treatment (I₂). N fertilization lead to greater values of WUE in all irrigation treatment.The effect of N fertilization on agronomic nitrogen use efficiency (NUE) was significant only at the first and second growing season.Giant reed was able to uptake water at 160–180 cm soil depth when irrigation was applied, while up to 140–160 cm under water stress condition.Giant reed appeared to be particularly suited to semi-arid Mediterranean environments, showing high yields even in absence of agro-input supply.     

Effects of Two Underseed Species, Medicago polymorpha L. and Scorpiurus muricatus L., on the Yield of Main Crop (Durum Wheat) and Subsequent Crop (Teff) Under Humid Moisture Regimes in Ethiopia

Mixed cropping of leguminous underseed species and cereal crops may increase productivity and serve some additional purposes. Two leguminous weed species which are widely distributed in annual crops of the Ethiopian highlands have been studied with varying coverage in greenhouse trials in Ethiopia with regard to their suitability as underseeds and with wheat ( Triticum turgidum [L.] Thell. var. durum [Desf.] MacKey) as a main crop. The competitive effects of Scorpiurus muricatus L. on the grain yield of wheat were smaller than those of Medicago polymorpha L. (-14.1 % and -23.6 % respectively, compared with the underseed free control) which is mainly ascribed to differences in their speed of development and shoot height. The residual effects of the underseed's root masses on the grain yield of the successive teff crop (Eragrostis tef [Zucc] Trotter) were significantly higher with Scorpiurus muricatus (+99.3 %) than with Medicago polymorpha (+63.6 %). The results are discussed with regard to the specific site conditions in the cereal-dominated cropping systems of the Ethiopian highlands.     

粳型水稻形态遗传分化与杂种优势的研究

利用9个不同生态类型的50份水稻亲本材料,以生态型为单位进行双列杂交,配制366个组合,依据形态指数研究了各类型粳稻品种的形态遗传分化以及遗传分化与杂种优势的关系。结果表明:各生态型间形态指数差异与其F_1杂种优势相关不显著,但形态上籼粳分化的差异是杂种优势产生的重要基础。     

Variation of the storage protein phaseolin in common bean (Phaseolus vulgaris L.) from the Mediterranean area

Summary Variation of phaseolin, the major storage protein in Phaseolus vulgaris L., was analysed in seeds of a germplasm collection from the Mediterranean area. Results showed a number of subvariants differing from the reference patterns for the presence, absence or faintness of single polypeptides. Maximum concentration of variation was found in the Cyprus material. Sources and causes of variation are discussed.