Durum wheat (
Desf.) is the main cereal crop in Italy, mostly cultivated in Southern and Central regions. Improving grain yield has been the primary objective of most national breeding programs until the end of the’ 70s. The objective of this study was to evaluate durum wheat yield stability improvements achieved in Italy over twenty years through the national breeding programs. Data from 10 coordinated field trials carried out over two 3-year periods (1977–79 and 1996–98) were considered. Analysis of the mean yield, linear regression coefficients (
), coefficients of variability (CV), coefficients of determination (
) and deviations from the regression (
d) allowed us to identify, for each period considered, remarkable differences among different cultivars in terms of yield and yield stability. The stability analysis clearly identified, during 1977–79, two different subgroups of genotypes. The first (
<1) included cultivars registered in the National Durum Wheat collection before 1974 (Cappelli, Capeiti 8, Trinakria. Appulo, Isa 1), having high adaptability to low-input environments. In contrast, the second subgroup (
>1) included semidwarf cultivars such as Valnova, Valgerardo, Creso and Valfiora, highly sensitive to environmental variability and pronounced responsiveness to high-input environments. In 1996–1998 yield stability became a primary target. Therefore the national breeding programs promoted comparative trials over-time and over-space. All cultivars selected in those years had
values close to 1 and their mean yield was significantly higher compared to the 1977–79 cultivars. As a result, the most recent cultivars possess both high adaptability traits (typical of those tall cultivars selected in arid and semiarid regions before the 70s) and high yield potential, a trait associated with
alleles (Creso and “Val” cultivars).
Authors:C. Riefolo, D. Ficco, L. Cattivelli, and P. Vita
The genetic variations of high and low molecular weight glutenin subunits (HMW-GS and LMW-GS) as well as of ω- and γ-gliadins in 562 accessions of 7 tetraploid Triticum turgidum L. subspecies were investigated using sodium dodecyl sulfate polyacrylamide-gel electrophoresis (SDS-PAGE). A total of 26 HMW-GS alleles (7 at Glu-A1 and 19 at Glu-B1 loci) with 63 allelic combinations, as well as 11 LMW-GS alleles (5 at Glu-A3, 4 at Glu-B3 and 2 at Glu-B2 loci) with 26 allelic combinations, were detected. Two novel HMW-GS, called B1cf and B1cg, were discovered in T. dicoccum, B1cg was also found in T. turanicum. The Glu-B1 locus showed the highest values of genetic diversity index (H), with a mean of 0.72. As regards gliadins, 8 alleles at Gli-B1 locus have been found. The dendrogram based on allelic frequencies, revealed that T. durum, T. carthlicum and T. polonicum grouped a part from the other subspecies. This behaviour suggested probably different evolutive pathways among the tetraploid wheats.
Authors:G. Mangini, D. Nigro, B. Margiotta, P. De Vita, A. Gadaleta, R. Simeone, and A. Blanco
During the last century wheat landraces were replaced by modern wheat cultivars leading to a gradual process of genetic erosion. Landraces genotyping and phenotyping are strategically useful, as they could broaden the genetic base of modern cultivars. In this research, we explored Single Nucleotide Polymorphism (SNP) markers diversity in a collection of common and durum wheats, including both landraces and Italian elite cultivars. A panel of 6,872 SNP markers was used to analyze the genetic variability among the accessions, using both the Principal Components Analysis (PCA) and the Neighbour Joining clustering method. PCA analysis separated common wheat accessions from durum ones, and allowed to group separately durum landraces from durum elite cultivars. The Neighbour joining clustering validated PCA results, and moreover, separated common wheat landraces from common elite cultivars. The clustering results demonstrated that Italian durum landraces were poorly exploited in modern breeding programs. Combining cluster results with heterozygosity levels observed, it was possible to clarify synonymy and homonymy cases identified for Bianchetta, Risciola, Saragolla, Timilia and Dauno III accessions. The SNP panel was also used to detect the minimum number of markers to discriminate the studied accessions. A set of 33 SNPs were found to be highly informative and used for a molecular barcode, which could be useful for cultivar identification and for the traceability of wheat end-products.
Authors:S. A. Colecchia, P. De Vita, and M. Rinaldi
A 2-year conservation agriculture experiment was conducted in Southern Italy on durum wheat continuous cropping. Aim of the research was to assess the durum wheat productivity and grain quality in reduced soil tillage systems, according to conservation agriculture principles. The interactions among experimental treatments and climate revealed a close relationship among grain yield, grain quality and wheat growth conditions. Specifically, conventional tillage (CT, plowing and 2 disc harrowing) showed in the 2-year period higher grain production than reduced tillage treatments, minimum (MT, 1 disc harrowing) and No tillage (NT), especially for good crop water availability (3.29 t ha–1 of grain yield in CT, 2.67 in MT and 2.54 in NT). The amount of rainfall (above the average in both years) and its distribution in the growing seasons (more regular in the first year) strongly influenced wheat-grain quality indices (11.97% of protein content in the first year and 9.82% in the second one). Also, the wheat quality resulted more sensitive to the “Year × Tillage” interaction, with differences among tillages more evident in the second year and favourable to NT and MT. Spectral vegetation indexes (NDVI and TVI) measurements at flowering, have been shown to be useful to support farmers in N-late application for improving grain wheat quality. From this experiment carried out during the conversion period and in wet years, wheat managed with CT resulted in higher grain yield and quality, while only test weight showed a significant “Year × Tillage” interaction. Further indications emerged on the need to supply additional (10–20%) seed amount at sowing and crop nitrogen fertilizer in the first transition years in reduced tillage systems compared to conventional ones.