Paolo Annicchiarico

Biodiversity in a germplasm collection of durum wheat

SummaryOver 7,600 durum wheat accessions belonging to 22 country gene pools were evaluated in Syria, during the seasons 1985–86 through 1987–88 under semi-arid Mediterranean climatic conditions. Data on seven agronomic traits are presented to assess the distinctiveness and the phenotypic diversity of these pools. Univariate statistical analysis revealed differences among materials of diverse origins for all traits. Mean phenotypic diversity within countries was highest in the germplasm from India, lowest in that from Bulgaria. In a canonical variate analysis, the first three canonical variables explained 77.7% of the total variance. A cluster analysis was performed to supplement the generated information by the canonical analysis. The multivariate analyses evidenced the distinctiveness of the Ethiopian germplasm. The gene pools from Syria and Jordan, closely resembling each other, appeared separate from all others. A certain peculiarity was also shown by the germplasms from Greece, Morocco and France, while the remaining countries clustered into four groups. The results of the present evaluation could provide useful information for breeding activities, germplasm collection, and establishment of ‘core’ collections. Evidence is presented that environment played a major role in creating the overall variation for the considered traits, although germplasm exchange seemed also an important factor.

Diversity, genetic structure, distinctness and agronomic value of Italian lucerne (Medicago sativa L.) landraces

Eleven landraces belonging to the seven commercial ecotypes of northern Italy, and seven elite varieties, were evaluated with the aims of: (i) comparing landrace and variety germplasm for dry weight (DW, recorded across three harvests spanning over two years) and morphophysiological characteristics; (ii) estimating among-population (sA2) and within-population (sW2) genetic variances of landrace and variety germplasms; (iii) investigating the interrelationships among traits at the plant and the population levels; (iv) exploring patterns of phenotypic diversity, and the relationships between diversity and environmental variables at landrace collecting sites; and (v) assessing the distinctness of ecotypes. Some 256 or 512 genotypes per landrace, and 128 genotypes per variety, were grown in dense stand in an unreplicated design together with a replicated clone. Compared with varieties, landrace material showed higher total DW (+9%) and DW at the last harvest (+43%), lower (2.5-fold) summer mortality and autumn dormancy (P< 0.01), and similar winter mortality. Landraces exhibited a greater sW2value than varieties for all traits except autumn dormancy and number of florets per inflorescence (P< 0.01), with sW2always exceeding sA2(P< 0.01). The ratio of sW2to sA2averaged 23.1 for landraces and 6.5 for varieties across eight traits. Frequency of mowing at collecting sites was associated with higher total DW, better persistence, lower summer and winter mortality, larger leaflets and more stems per plant (r≥ 0.66, P< 0.05). Cluster analysis showed that landraces geographically close or belonging to the same commercial ecotype tended to greater similarity. However, one landrace that evolved under very frequent mowing differed greatly from other landraces of the same ecotype. Based on discriminant analysis, two ecotypes may be sufficiently distinct for registration in a sui generissystem, even though they may not meet the criteria for registration under a homegenity requirement

Agronomic value and plant type of Italian durum wheat cultivars from different eras of breeding

Durum wheat has been subjected to intense breeding in Italy due to its local economic importance. Four groups of Italian cultivars representative of different breeding eras were compared in northern Syria for yield potential and morphophysiological features at a moderately favourable site, and drought tolerance at a stressful site. Group 1 included indigenous landraces; Group 2 comprised genotypes selected from exotic landraces (released in 1920s–1930s); Group 3 included genotypes selected from crosses or mutagenesis involving Group 2 materials (1950s–1960s); Group 4 comprised genotypes selected from crosses between CIMMYT and Group 2 materials (from 1970s). Under moderately favourable conditions, a yield increase of 1.03 t ha–1 was observed from Group 1 through Group 4, corresponding to a genetic gain of about 0.017 t ha–1 per year. Such increase was only partly accounted for by a parallel increase in spike fertility and seed weight. Plant stature decreased dramatically from Group 1 to Group 4; a remarkable reduction of height was already attained in Group 3, before the introduction of dwarfing genes from bread wheat. Earliness of heading and grain filling duration increased consistently across breeding phases, the length of crop cycle remaining almost unaltered. No significant improvement of drought tolerance resulted from the breeding activity, suggesting the need to put more emphasis on selection for real stress tolerance rather than escape. Overall variation for morphophysiological traits, assessed by a principal components analysis, highlighted the great diversity among the Group 1 cultivars, while variation within Groups 3 and 4 was lower. Indigenous landraces, little used in the breeding history, as well as novel, unexploited exotic germplasm sources could contribute to broaden the crop genetic base in the region.

Variation for dry matter yield, seed yield and other agronomic traits in Ladino white clover landraces and natural populations

SummaryA set of Ladino white clover ecotypes including the last available landraces and some natural populations collected from old permanent meadows, together with some white clover varieties of various origins, were evaluated as monocultures for dry matter (DM) and seed yield assessed in separate field experiments. Other agronomic traits were also recorded. The best performing variety, ‘Espanso’, was significantly outyielded by some ecotypes for DM and seed production. Compared to landraces, natural populations yielded on average far less seed but as much DM and tended towards higher persistence indicating that domestication of the native Ladino at the farm level only improved seed yield of the crop. Natural populations showed, besides lower values of most seed yield components, a distinct canopy architecture characterized by smaller leaves, longer internodes and denser stolons. Seed weight proved the best character discriminating between the two ecotype groups. Significant variation for most traits was found both among landraces, in which it was mostly relatable to differences among provenances, and among natural populations. The relations between the main multivariate patterns of phenotypic variation and a set of environment collecting variables suggested that evolutive adaptation to different agronomic practices was a major determinant of the overall variation found in landraces. Evidence is provided that a relevant part of the variation observed among ecotypes for some important traits could be genetic.

Yield vs. morphophysiological trait-based criteria for selection of durum wheat in a semi-arid Mediterranean region (northern Syria)

Abstract The value of germplasm-specific and general indexes of selection based on morphophysiological traits was assessed as an alternative to conventional yield-based selection for grain yield improvement of durum wheat in a semi-arid Mediterranean region. General indexes were developed from the evaluation of a collection of 503 landrace accessions. Specific indexes were also defined for each of the durum wheat types mediterraneum typicum and syriacum as well as for a third germplasm group including mostly Mediterranean material pertaining to neither of these types. Indexes included two or three traits among the following: displacement from optimal heading date (difference in absolute value of days from the mean heading date of three control cultivars), early growth vigour, kernels per spike and kernel weight, the two yield components being alternative to each other. The efficiency of selection criteria was assessed in another set of 64 entries in terms of predicted yield responses and actual yield gains over target environments other than that of selection. Each of the three environments acted by turns as the selection environment and the remaining two as the target environments. These environments allowed for the assessment of selection criteria over a wide range of seasonal rainfall and mean yield levels. Large genotype×environment interaction was observed for yield and early vigour. Ranking of selection indexes for predicted and actual yield responses were fairly consistent, indicating an advantage of general indexes. The best among them, including heading displacement and kernels per spike, was, on the average, 20% and 11% more efficient than yield-based selection in terms of predicted and actual responses, respectively. The advantage of this index was the consequence of the absence of covariation and the moderate to high values of genetic correlation with yield over target environments, heritability and ratio of genotypic to genotype×environment interaction variance of its component traits.

Developing a tall durum wheat plant type for semi-arid, Mediterranean cereal–livestock farming systems

Abstract Durum wheat cropping in semi-arid areas of West Asia and North Africa is frequently integrated into a cereal–livestock farming system. The wheat straw, mostly used for feeding animals, represents an important commodity, its average sale price per unit weight being not less than 40% of that of grain in three recently surveyed areas. There is uncertainty whether the widespread, short-statured wheat plant type could be economically preferable in these environments relative to a tall type, especially when considering straw yield. Within the Mediterranean durum wheat gene pool, mediterraneum typicum germplasm possesses a markedly tall stature, implying high straw yield. In a first phase of evaluation under prevailing conditions of northern Syria, 13 entries characterized by early heading and good agronomic performance were identified from a collection of about 2000 Tunisian and Algerian accessions. In a second phase reported here, these entries were evaluated in relation to two widely grown adapted cultivars, i.e., the semi-dwarf variety ‘Cham 1’ and the local landrace ‘Haurani’, across four environments of northern Syria diversified for rainfall and soil characteristics. In an economic assessment, the straw value was expressed in terms of grain-equivalent, defining an economic yield as: grain yield +(0.40× straw yield ) . Compared with the control cultivars, the mediterraneum typicum entries were taller but tended to later heading with a similar grain filling duration. However, a few entries as early as the controls were also found. Almost all exotic entries outperformed ‘Haurani’ for economic yield. Two entries showed significantly higher (P 12%) and aerial biomass across environments than ‘Cham 1’, owing to higher straw yield and similar grain yield. They compensated for the relatively lower spike fertility by heavier kernels. Genotype×environment interactions were generally limited for yield-related traits. Straw yield was closely associated with plant height (r=0.76, P

Variation in cold tolerance and spring growth among Italian white clover populations

Seven populations collected at different altitudes in northern Italy, two Ladino breeding populations and two control cultivars (AberHerald and Grasslands Huia) of white clover (Trifolium repens L.) were included in a series of experiments analysing: (i) levels of cold tolerance using artificial and field-based methods; (ii) relationships between these measures of cold tolerance; (iii) components of spring yield, various physiological traits, and their relationships with cold tolerance. Rates of seedling and growing point mortality in the populations over winter, assessed in separate field experiments, were closely related (r = 0.85). Grasslands Huia showed the highest death rates, and material originating from high altitudes the lowest. The LT50 value, i.e., the temperature at which 50% of the growing points would die, estimated by an artificial freezing test, was significantly correlated with field-based measures of seedling (r = 0.64) and growing point (r = 0.84) mortality. The existence of these correlations is of potential interest for the development of indirect selection criteria for complex and expensive-to-evaluate traits such as winter survival in field plots. Besides being reliable, in this study the artificial assessment was also sensitive, providing a greater degree of separation of the populations means than field-based measures. Of the several physiological traits (water content,concentrations of water soluble and total non-structural carbohydrate, and water soluble protein content of stolons) measured at a mid-winter sampling date under field conditions, the only character showing significant variation between populations was soluble protein content. There was a slight trend for material with a higher protein content to exhibit greater field-based values of cold tolerance. High altitude populations tended to have low spring yields. The highest spring yield was found in one of the Ladino populations. The study identified two populations which combined, to differing extents, cold tolerance and spring yield characteristics that would be of potential use in breeding for specified agronomic/climatic zones.

Characterizing the molecular and morphophysiological diversity of Italian red clover

Red clover (Trifolium pratense L.) is the third major forage species in Europe, but there is limited information on the biodiversity and the genetic structure of landraces and natural populations which evolved in this region. The objective of this study was producing such information for Italian germplasm on the ground of molecular and morphophysiological diversity. The study included 16 Italian natural populations from a wide range of environments, four landraces representing the four traditional commercial ecotypes, and two varieties. Eight morphophysiological traits were assessed in a replicated trial under field conditions, whereas two AFLPs primer combinations with 140 polymorphic markers were recorded on a random sample of 13 genotypes per population. Ordination and classification results based on morphophysiological data clearly kept track of the type of germplasm (i.e. landrace or natural population) and its geographic origin, unlike results based on molecular markers. Euclidean distances among populations based on morphophysiological traits were not correlated with Nei’s genetic distances based on molecular markers according to Mantel’s test. Geographical distances among landrace or natural population material was correlated with distances based on morphophysiological traits but not with those based on molecular markers. The average within-population variation estimated via molecular markers was about 2.6-fold higher than that among populations, preventing an acceptable discrimination among most populations. On average, natural populations tended to have within-population variation similar to varieties and somewhat lower than landraces. Our results have implications for collection, conservation, exploitation and registration in a sui generis system of red clover genetic resources.

Diversity of white and narrow-leafed lupin genotype adaptive response across climatically-contrasting Italian environments and implications for selection

White lupin (Lupinus albus) and narrow-leafed lupin (L. angustifolius) have special interest as high-protein feed crops but their cultivation is limited by low grain yields. This study aimed to support breeding programs targeting Italy or other climatically variable south-European regions by investigating within-species adaptation patterns across contrasting Italian environments. An additional aim was comparing species for yielding ability. Eight narrow-leafed and six white lupin cultivars featuring different origin, phenological type (Mediterranean in both species; winter in white lupin; spring in narrow-leafed lupin) and plant architecture (determinate or indeterminate in both species; tall or dwarf in white lupin) were evaluated in a Mediterranean and a subcontinental-climate site under autumn and late-winter sowing. Additive main effects and multiplicative interaction was preferable to joint regression for modeling yield responses. In both species, cross-over GE interaction was observed (Pxa0<xa00.05), autumn-sown Mediterranean and subcontinental environments were the most-contrasting for GE effects, and widely adapted material included cultivars of Mediterranean phenological type with indeterminate growth. Material with determinate growth was not among the best-yielding entries in any environment, whereas a dwarf winter-type white lupin entry was specifically adapted to autumn-sown subcontinental environments. White lupin displayed larger genetic variation than narrow-leafed lupin for phenology and other traits. Relationships of morphophysiological traits with grain yield were environment-specific and were locally high for some white lupin traits (early flowering, long reproductive phase, high aerial biomass, low proportion of pod wall). White lupin exhibited higher yielding ability than narrow-leafed lupin in all environments but the late-winter sown Mediterranean one, when comparing locally top-yielding cultivars.

Morpho-physiological traits to complement grain yield selection under semi-arid Mediterranean conditions in each of the durum wheat types mediterraneum typicum and syriacum

SummarySome 238 landraces from Algeria and Tunisia representative of the mediterraneum typicum durum wheat type and 265 landraces from Syria and Jordan representing the syriacum type were grown in a semi-arid Mediterranean environment of Northern Syria characterized by moderate drought stress. The germplasm types were compared for mean value, level of variation and relationships with grain yield of various morpho-physiological traits possibly usable for indirect selection of best yielding materials. The syriacum germplasm showed higher yield mainly due to greater earliness of cycle, slightly longer grain filling period, shorter stature, lower early growth vigour and higher drought tolerance expressed by a visual score recorded in another, more stressful environment in the region. It also showed lower variation for all morpho-physiological characters except plant glaucousness, for which it was more variable. The wheat types differed not only for architecture but also for optima of individual morpho-physiological traits required to maximize the yield response in the given environment. Higher yield of syriacum materials was attained at same heading and three to four days delayed maturity with respect to average phenology of three well-adapted control cultivars, and it was favoured by increasing number of kernels per spike, early vigour and drought tolerance. Higher yield of mediterraneum typicum landraces was related to heading and maturity dates approaching those of the control cultivars and to increasing kernel weight, early vigour and drought tolerance. Plant stature hardly affected the yield. Both absent and strong glaucousness could confer a yield advantage in syriacum materials.