A recurrent selection programme for grain yield in winter barley

Summary The effect of a recurrent selection procedure was evaluated in a winter barley (Hordeum vulgare L.) population. Cycle zero (C₀) was initiated by crossing six high yielding winter barley cultivars with the short straw cv Onice. The F₁'s were crossed according to a diallel scheme without reciprocals. A total of 750 S₀ plants were derived and evaluated; 329 S₀ plants were selected and their progenies (S₁ lines) tested. Fifteen S₁ lines were chosen and used as parents of cycle 1 (C₁), by producing 105 F₁ hybrids which simulated a random mating offspring. One hundred and three randomly chosen S₁ lines belonging to C₀, and 103 S₁ lines belonging to C₁, were evaluated at two locations.For grain yield a significant difference between cycles was observed. From C₀ to C₁ the grain yield increased with 307 g/m². This increase was due to a higher number of seeds per m². For plant height, heading date and 100-kernel weight no differences between cycles were observed.The positive results obtained in this study indicate the potential usefulness of recurrent selection for developing parents or lines superior for grain yield, with little change in other important agronomic traits.     

Effect of Agronomic Factors on Annual Leguminous Forage Crop in Mediterranean Environments

Dry matter and seed production of five annual leguminous species hairy vetch ( Vicia villosa Roth cv. Orsara) , crimson clover ( Trifolium incarnatum L. ecotype Campano) , squarrosum clover ( T. squarrosum L. ecotype Calabro) , persian clover ( T. resupinatum cv. Accadia) and fenugreek ( Trigonella foenum-graecum L. ecotype Maltese) was estimated in 1989–90 under two density and irrigation rates and with two cutting treatments. The experiments were done at the Forage Crops Institute of Foggia, which has a typical Mediterranean environment. The forage cut severely affected the regrowth of the plants in all species. The year and irrigation factors affect dry matter, seed production and seed yield components more than the plant density rates. The averages over the years, for dry matter and seed yield were 21.0 % and 20.5 % higher in the irrigated than the not irrigated ones. The lower plant density rate, for seed yield trait, gave better result in hairy vetch in irrigated and non-irrigated treatment. Whereas in the other species, the lower rate of planting gave greater yield under non-irrigated and the higher rate under irrigated growing condition. The seed yield components most influenced by irrigation were: thousand seed weight and seeds/pod in hairy vetch and heads/tiller and seeds/head in clovers species. Fenugreek was the earliest forage crop (cut at the beginning of March), followed by crimson and persian clovers (cut at the middle of April) and squarrosum clover and hairy vetch (cut in the middle-late of May). All the cultivars and ecotypes considered not regrowth after cut and could represent an important fresh forage resource for the period March–May for the Mediterranean regions.     

Phenotypic Variability for Bio-Agronomical Traits in Berseem (Trifolium alexandrinum L.) Populations of the Meskawi Botanical Group

The phenotypic variability and adaptability for bio-agronomic traits in berseem populations (Trifolium alexandrinum L.), was evaluated. The number of genotypes was 32 (26 of southern Italy origin and 6 Egyptian). They were evaluated under field conditions for two years (1989–90) in Foggia (Italy) adopting different cutting regimes: at 7–8th inter-nodes stem length, beginning of flowering, and no cutting. The genotypes of the Italian origin appeared to be better adapted when the cut was applied in the early stage of development, and more productive in seed yield. The Egyptian populations were most productive in forage in the later cuts and had a higher seed weight. The range of variation among the bio-agronomical traits was higher when the cut was applied at early flowering. The traits with wider range of variation were: dry matter, plant height at cut, regrowth at the fourteenth day after cut, tiller density and seed yield. Considering a multiplicative selection index, 6 populations were well adapted and could be used as parents in breeding programs and in extended farm cultivation.     

Residual fertilizer effects on dry-matter yield and nutritive value of Mediterranean pastures

Five pastures in an Mediterranean environment in southern Italy were fertilized for 6 years (1993–1998) with nitrogen (N) fertilizer, phosphorus (P) fertilizer and two levels low (L) and high (H) of combined nitrogen and phosphorus fertilizer (N‐P), and compared with a no‐fertilizer control treatment, and the effects on soil variables, dry matter (DM) yield of herbage and floristic composition of the pastures measured. From 1998–2002, half of each plot was fertilized with the same treatments (continued treatment) while the other half received no fertilizer (discontinued treatment). In the year 2001–2002, the plots on the discontinued fertilizer treatments and the plots on the control treatment were used to evaluate the residual effects of the fertilizer treatments. The P and N‐P fertilizer continued and discontinued treatments, in comparison to the control treatment, had a higher content of available P₂O₅ in the soil while under the N fertilizer treatment it decreased. The N and P fertilizer treatments and the residual effects of these treatments led to higher DM yields and proportions of Gramineae and Leguminosae, respectively, compared to the control treatment. Furthermore, differences in the nutritive value of the herbage and floristic composition were observed between the N‐P fertilizer treatments and the control treatment. The residual effect of the N, P and N‐P fertilizer treatments increased DM yield proportionately by 0.063, 0.385 and 0.404, respectively, and reduced the crude protein content of the herbage. The residual effects of the fertilizer treatments on milk forage units (MFU) were 261 for N, 1107 for P and 1003 MFU ha^?1 for N–P fertilizer treatments. Among fertilizers, the residual effect of the N‐P fertilizer treatment promoted an increase in DM yield but produced little variation in floristic composition of the pasture. In general, the fertilizer treatments increased DM yield and nutritive value of herbage and reduced floristic composition in pastures on these Mediterranean sites.     

Effects of temperature and photoperiod on flowering time of forage legumes in a Mediterranean environment

Flowering time plasticity is a commonly occurring adaptive characteristic of fodder crops, including legumes, in arid and semiarid environments of the Mediterranean regions. Time of flowering is mainly influenced by genotype, temperature and photoperiod. Field experiments were carried out at Foggia (southern Italy) during successive growing seasons (from 8 to 16 growing cycles according to species) to study the relation among air temperature, photoperiod and duration of the morphological development of flowering in eight forage legume species: sulla (Hedysarum coronarium L.), sainfoin (Onobrychis viciifolia Scop.), pea (Pisum sativun L.), berseem clover (Trifolium alexandrinum L.), Persian clover (Trifolium resupinatum L.), faba bean (Vicia faba L.), common vetch (Vicia sativa L.) and hairy vetch (Vicia villosa Roth). Time to reach 10% flowering (EF) and 100% flowering (FF) were recorded. Rate of progress to flowering, defined as the inverse of time from sowing to EF and FF, was related to mean daily temperature, or to both mean daily temperature and mean photoperiod. Using the linear equations, the thermal time requirements (T_t) and the base temperature (T_b) expressed as heat units were determined by the x-intercept method for both EF and FF stages. Evaluation of flowering time was also based on days after planting (DAP), day of year (DOY) and on a photothermal index (PTI). For all species, a significant negative correlation (P ≥ 0.01) was found between planting date (PD) and DAP whereas PTI showed a significant negative relationship (P ≥ 0.05) only for faba bean, pea, berseem clover and common vetch. In sainfoin, sulla and berseem clover, the rate of progress to flowering was affected significantly (P ≥ 0.05) by both mean temperature and photoperiod. The T_t requirements to reach the EF and the FF stage ranged from 871 to 1665 °C day and from 1043 to 1616 °C day, respectively, for the studied species. Both phenological stages considered depended upon accumulated thermal time above a species-specific base temperature. Furthermore, in all legumes the onset of flowering only occurred when dual thresholds of a minimum T_t and a minimum photoperiod were reached, which were specific to each species.     

Seed quality differences between normal,floury-2 and opaque-2 maize inbreds

Summary 142 inbreds of maize (Zea mays L.) and their fl2 and o2 versions, have been compared for seed quality traits. On average, fl2 is superior to the normal and o2 maizes in protein and oil contents and intermediate between normal and o2 in tryptophan content and DBC value. The introduction of the two mutant alleles drastically enhances the variation of the quality traits DBC value and tryptophan content. In association with the higher protein content of the fl2 versions, this effect makes it possible to identify a group of fl2 genotypes with high protein content (14.06%) and high DBC value (65.55), tryptophan content (1.32%) and oil percentage (5.92%).Supported by the Commission of the European Communities, contracts no 437 and 438.     

Genetic variability in herbage and seed yield in selected half-sib families of berseem clover, Trifolium alexandrinum L.

Berseem clover Trifolium alexandrinum L. is an annual forage legume commonly grown in pure stands and in grass mixtures in the Medi-terranean basin. Six populations were naturally cross-pollinated in 1990 and 1991 by a half-sib breeding method. In 1992 and 1993. 54 half-sib maternal plants, six original populations, and six advanced populations were field evaluated for forage (short cycle, harvest made at seven or eight inlernodes: long cycle, harvested at flowering) and seed yield (no forage harvest) in experiments at the Forage Crop Institute at Foggia, Italy (typical Mediterranean location). Genetic variability, narrow-sense herilability, genetic and phenotypic correlations among forage and seed yield component trails were investigated. The genetic variance in dry matter among maternal half-sib populations in short cycle was 51% greater than in long cycle. Narrow-sense heritabilily was 35% higher in short cycle than long cycle for dry matter and 26% higher for seed weight than seed yield. The magnitude of the genetic variance components and genetic correlations suggested that selection among plants of maternal half-sib populations would be more effective for improving dry matter in short than in long cycle harvests. The selection applied in the study was not effective for increasing seed yield per se however, the trait may be increased by selecting indirectly for seed weight.     

Effects of irrigation and harvest management on dry-matter yield and seed yield of annual clovers grown in pure stand and in mixtures with graminaceous species in a Mediterranean environment

Forage crops in Mediterranean environments are characterized by variable seed and forage production. Knowledge of the effects of agronomic factors on annual clovers grown in pure stand and in association with grasses is essential for their effective exploitation of the available environmental resources. Herbage and seed production were evaluated in southern Italy in an experiment with winter annual forage crops during the years 1992–95. Clovers (Trifolium alexandrinum L., berseem; T. incarnatum L., crimson; T. resupinatum L., Persian; and T. squarrosum L., squarrosum) and graminaceous forage crops (Hordeum vulgare L., barley; and Lolium multiflorum Lam., Italian ryegrass) were used to examine the agronomic effects of irrigation and harvest management. The clovers were evaluated in pure stand and in mixture, whereas the graminaceous species were evaluated only in mixtures. The mixtures were sown in alternating, equally spaced rows. The parameters evaluated were forage dry-matter yield, seed yield and its components. The results showed wide differences in forage production between clovers in pure stands and in binary mixtures. Mean dry-matter production from forage harvest of pure stands of irrigated clovers taken when 10–15% of the stems were flowering yielded 4·36 t ha^–1, that is 0·67 and 0·55 of that of irrigated mixtures of clovers with either Italian ryegrass or barley, respectively, harvested when 10–20% of the graminaceous components were at the heading stage. The forage yield of non-irrigated pure stands of clovers was 0·60 of that of irrigated plots, whereas non-irrigated mixtures yielded 0·82 and 0·86 of that the irrigated treatments for Italian ryegrass or barley mixtures. The mean seed yield of non-irrigated pure stands of the clovers was 0·51 of that of irrigated stands, which yielded 451 kg ha^?1. Persian clover gave the highest seed yields (732 kg ha^?1 under irrigation). These higher yields were related to a higher number of fructiferous organs per stem in Persian clover. When a forage harvest had previously been taken on irrigated clover plots, the subsequent mean seed yields were greatly reduced to 0·76 for berseem and 0·21 for Persian clover and were almost negligible for crimson and squarrosum clover. When irrigated and grown in mixtures with Italian ryegrass, only berseem produced a worthwhile yield of 0·36 compared with that of pure clover taken for seed without a forage harvest; mixtures with barley gave yields of 0·71, 1·07 and 0·20 for berseem, crimson and Persian clovers, respectively, compared with seed yield from uncut pure clover.     

Effects of the Developmental Stage at Harvest on Dry Matter and Chemical Component Partitioning in Berseem

The influence of cutting applied at four stages of plant growth on dry matter, crude protein, total available carbohydrates and reducing sugar partitioning was examined in six genotypes of berseem ( Trifolium alexandrinum L.). The research was conducted in Foggia (Italy) during 1990 and 1991 in a glasshouse with controlled water application. The plants were grown in a plastic-lined, PVC cylinder. At each cut, dry matter and chemical components were evaluated in leaf, stem and root fractions; at the end of the biological cycle, seed yield was recorded.
Plants showed similar dry matter partitioning between leaves and stems at the eighth internode stage. The crude protein concentration was highest in leaf fractions, reaching the maximum value (31%) at an early stage of growth (fourth internode stage). The maximum value of total available carbohydrates was obtained in the stems at the early flowering stage (11 %), whereas reducing sugars almost always showed higher concentrations in the leaves (4 %). As for forage and seed yields, the developmental stage at cutting had a great influence on dry matter and chemical component partitioning among the different organs. Genotypic differences were observed for dry matter partitioning in leaves and stems in all developmental stages, but diversity in chemical component content was more evident in the roots.     

Effect of Phenological Stages on Plant Dry Matter Partitioning and Seed Production in Berseem (Trifolium alexandrinum L.)

Berseem clover ( Trifolium alexandrinum L.) is an annual forage crop widely grown in Mediterranean environments. Dry matter partitioning in the leaf, stem and root and seed production of three populations of Egyptian as well as Italian origin were evaluated under four cutting regimes. The cutting treatments were applied to the plants at different stages of plant development: at the fourth (A) and eighth nodes elongation (B), at early flowering (C) and physiological maturity of seeds (D), After herbage, harvest plants were utilized for seed yield and evaluation of its seed yield components. Higher dry matter and seed yield was obtained in treatments D and B, respectively. In the other treatments, dry matter content was lower than in treatment D and related to the phenological development of the plant. Dry matter content in the root was higher when the cut was applied at early flowering. Cutting regimes influenced plant mortality, with the number of dead plants increasing from the cut applied in early (A) to that in the final treatment (D). Cuts applied at early stage of development depleted root reserves causing plant death. This peculiarity could be a tool for selecting populations with higher persistence and with a more tolerant physiological response to stress imposed by cuts. The populations of Egyptian origin, in comparison with the Italian ones, were more productive in dry matter in the early stage of growth and in all treatments were higher in seed weight.