Identification of cultivars and accessions of Lolium, Festuca and Festulolium hybrids through the detection of simple sequence repeat polymorphism

Molecular diversity and genetic affinity in the Lolium/Festuca grass complex have been assessed using simple sequence repeat (SSR) marker technology. The genotypic set was derived from three accessions of perennial ryegrass, two cultivars of Italian ryegrass, two cultivars of meadow fescue, two cultivars of tall fescue and 10 accessions from different intergeneric hybrid (Festulolium) combinations. The majority of the genomic DNA‐derived SSR primer pairs from perennial ryegrass (LPSSR) and Italian ryegrass (LMSSR) produced clear, simple and distinctive amplification products from the majority of the genotypes. The efficiency of cross‐specific amplification for LPSSR markers varied from 38% in meadow fescue to 93% in two cultivars of Festulolium and from 57% in meadow fescue to 87% in Italian ryegrass for LMSSR markers. Of 40 amplified markers, 14 (35%) produced species‐difference alleles in the relation to cultivars used in the present study. Thirty‐five LPSSR locus‐derived alleles were found to be specific to Lolium species, four to meadow fescue and six to tall fescue. For LMSSR alleles, eight were specific to Lolium species and five were only associated with Italian ryegrass, and null alleles were detected for meadow fescue in all instances. These species‐difference markers could clearly identify different accessions of Festulolium. Cluster analysis separated the individual taxa and showed grouping of intergeneric hybrids based on genomic composition. The data distinguished between the species and reflected the known pedigree of the cultivars and the differences between the species. The dendrogram also distinguished between the Festulolium accessions and clearly demonstrated the relations between Festulolium hybrids and their parent species.     

Genomic constitution of Festulolium cultivars released in the Czech Republic

Genomic in situ hybridization (GISH) was used to characterize the chromosome constitutions of individual plants from a set of tetraploid and hexaploid cultivars of Festulolium developed and released in the Czech Republic from hybrids of Lolium multiflorum with Festuca pratensis and F. arundinacea. A simplified GISH protocol readily discriminated parental genomes in the hybrids and facilitated the screening of large numbers of plants per accession. The contribution of parental genomes in the cultivars tested ranged from predominance of chromatin from one of the parents to a more balanced contribution from both parents. However, in none of the cultivars were equal proportions of chromatin from both parents present. The parental contribution to the hybrids was both in the form of complete chromosomes or as chromosome translocations. In hexaploid cultivars from (L. multiflorum × F. arundinacea) × F. arundinacea hybrids the average numbers of complete L. multiflorum chromosomes ranged from 4.95 to 7.5 and the numbers of translocations from 6.33 to 10.21. Two tetraploid cultivars from (L. multiflorum × F. arundinacea) × L. multiflorum hybrids showed a strong prevalence of L. multiflorum chromatin and intergeneric translocations were rare. In the tetraploid cultivar ‘Perun’ of the L. multiflorum × F. pratensis hybrid there were 11.7 chromosomes of L. multiflorum and 14.7 recombined chromosomes on average. Reasons for the domination of one of the parental genomes in hybrid cultivars are not clear and are only partially explained by breeding history. Recombination rates of individual genomes in hybrids involving F. arundinacea were evaluated in double hybridization experiments. The results indicated a strong affinity of the L. multiflorum genome for the F. pratensis genome present in F. arundinacea and little affinity for the F. glaucescens genome. This suggests that introgressions from F. arundinacea into L. multiflorum are primarily limited to the F. pratensis genome which can be more readily accessed in L. multiflorum × F. pratensis hybrids.     

The Effect of Sward Management on the Mineral Content of Winter Grazed Herbage

No information is available regarding the mineral content of autumn‐saved herbage during winter grazing under Central European conditions. Therefore, P, K, Na, Mg and Ca concentrations of autumn‐saved growths of Festuca arundinacea and Lolium perenne were analysed considering the potential influence of pre‐utilization (saved from June or July), date of winter harvest (December, January, February) and year (three winters). For all years date of winter harvest was the main source of variance, whereas date of preceding cut had no relevant effect on the mineral concentrations during winter. Already in December P [2.3 to 4.0 g kg^?1 dry matter (DM)], Na (0.3 to 3 g kg^?1 DM) and Mg (1.0 to 2.4 g kg^?1 DM) concentrations were mostly below the required levels for ruminants. The lowest values were detected in February. K levels ranged between 6.6 g kg^?1 DM in February and 23.4 g kg^?1 DM in December; on average, K concentrations decreased about 10 g kg^?1 DM with advancing winter. Ca concentrations (2.9 to 7.4 g kg^?1 DM) hardly changed during winter. Related to higher growth rates of F. arundinacea before December, P and Ca concentrations were diluted, but regarding Mg, more wintergreen F. arundinacea reached higher values than L. perenne especially at the beginning of winter.     

Accumulation of Secondary Metabolites Formed by Field Fungi in Autumn-Saved Herbage

Taking into consideration the fact that in recent years weather conditions were sufficient to feed cattle on pasture until late autumn or early winter, an experiment was carried out during the years 2000 and 2003 on a low input pasture to show the effect of the pre‐utilization date (June, July, August) and the harvest date in the autumn/winter period (November, December, January) on the accumulation of the following secondary metabolites formed by fungi: ergosterol (ERG), ochratoxin A (OA) and zearalenone (ZEA) in the autumn‐saved herbage. The highest levels of concentration of these metabolites were 470.3, 1.63 and 34.9 ng g^?1 respectively. Lower ERG levels were influenced by later pre‐utilization, which is a logical consequence of the shorter period of time for field toxigenic fungi development. Pre‐utilization in August is strongly recommended as the concentration of ochratoxin A (OA) in the autumn‐saved herbage in January was the lowest (not much changed in comparison with earlier harvest). Later harvest was also affected by higher ZEA concentrations in the analysed samples, which indicates that, under conditions of prolonged pasture utilization, field toxigenic fungi (producing ZEA) increased their population and had proper weather conditions stimulating the biosynthesis of the toxin. The later suggests that the final harvest of autumn‐saved herbage should be made rather in December than in January. Higher levels of humidity influenced higher concentrations of ERG and ZEA in the autumn‐saved herbage.     

Effects of Nitrogen Fertilization and Date of Utilization on the Quality and Yield of Tall Fescue in Winter

There is no information available on the influence of nitrogen (N) fertilization on autumn‐accumulated forage under Central European conditions. In this context, the metabolizable energy and the degree of fungal infection have never been examined before. In this study, the effects of the amount of N fertilizer (0, 50, 100 and 150 kg N ha^?1), the date of N application (July and August) and the date of winter harvest (December, January and February) on the quality and dry matter (DM) yield of Festuca arundinacea stands in winter were investigated. DM yield, the metabolizable energy and digestibility of organic matter (= in vitro rumen fermentation technique), crude protein, ADL (acid detergent lignin), and for the first time ergosterol were determined. Disregarding the 0 variant, no interactions of any relevance were present. DM yield, crude protein and values of ADL increased with increasing amounts of N, but the concentration of energy decreased. The late N application resulted mostly in lower DM yields but kept the forage physiologically younger, which brought about higher levels of metabolizable energy and lower concentrations of ADL. With later date of harvest, losses of mass and quality occurred. The degree of fungal infection rose as the amount of N fertilizer increased. Three years of investigation under different weather conditions, including interactions with the effects of N fertilization, provide a good base for generalization.     

Tall Fescue Adaptation to Low Nitrogen Fertilization in Relation to Germplasm Type and Endophyte Infection

Efficient crop growth with low nitrogen (N) application is becoming a requirement to face the concern on excessive N emission to the environment and the increasing cost of fertilizers. This study compared six natural populations and three improved varieties of tall fescue (Festuca arundinacea Schreb.) for dry‐matter yield over 4 years under ordinary N fertilization (450 kg ha^?1 in the 4 years) and very low N fertilization (only 40 kg ha^?1 prior to sowing). Both endophyte‐infected (EI) and endophyte‐free (EF) forms of each accession were sown. On average, ordinary fertilization implied 30 % higher yield than very low fertilization and the EI germplasm outyielded the corresponding EF germplasm (+4.4 %). Mean yield of improved varieties was higher than that of natural populations under ordinary fertilization (P < 0.05), whereas the two germplasm groups did not differ under very low fertilization. Accession × N fertilization interaction was found among natural populations but not among varieties (P < 0.05). A few natural populations were top‐yielding under very low fertilization and may be exploited, possibly in combination with endophyte infection, to select tall fescue varieties with enhanced performance under limited N application.     

Underground Vetch (Vicia sativa ssp. amphicarpa): A Potential Pasture and Forage Legume for Dry Areas in West Asia

Subterranean vetch [Vicia sativa ssp. amphicarpa (Dorth.) Aschers & Graebn.] is native to disturbed grasslands of the Mediterranean basin where heavy grazing, seasonal drought and erosion act as strong selection forces. It produces two pod types, above‐ground and 5 cm below the soil surface. Unlike subterranean clover (Trifolium subterranean L.), which buries its seeds after flowering above‐ground, subterranean vetch flowers and forms pods beneath the soil surface on underground stems. The aerial pods are produced after vegetative development ceases, while the underground pods are produced in ontogeny. The ability of this unusual vetch to survive in marginal areas with low rainfall (about 250 mm year^?1) and to produce nutritious herbage and pods is an important characteristic which helps address rehabilitation of degraded rangelands and increase feed production for small ruminants. Research at the International Center for Agricultural Research in the Dry Areas (ICARDA) during the 1988–93 growing seasons has assessed the herbage and seed productivity of underground vetch, its ability to grow in rotation with barley in marginal low‐rainfall areas, and its capacity to regenerate after heavy grazing. Drier conditions in 1989 favoured earlier underground flowering; the number of underground pods was higher than that of aerial pods. Grain yield of barley (var. Atlas) was around 2.0 t ha^?1 after underground vetch and only 1.2 t ha^?1 after barley. Grazing underground vetch had no effect on the productivity of the succeeding barley crop. The aerial and underground pods serve two distinct functions; aerial pods increase dissemination within suitable habitats, while underground pods increase the probability of plant survival under adverse conditions such as drought and heavy grazing. Underground vetch has two potential uses, namely the rehabilitation of marginal areas and production in rotation with barley.     

Management of Italian and Perennial Ryegrasses for Seed and Forage Production in Crop Rotations

Italian ryegrass (Lolium multiflorum Lam.) and perennial ryegrass (L. perenne L.) can be grown for seed and forage in cold winter regions provided the stand persists well over winter. Seed yield and plant characteristics during primary growth, and forage yield during regrowth, were determined for two Italian and one perennial ryegrass cultivars in Atlantic Canada. Establishment methods and dates included sowing ryegrass in cultivated soil alone or with barley in mid‐May and, after harvesting the barley crop, by sowing ryegrass following conventional or reduced cultivation and by no‐till drilling into barley stubble in mid‐August and early September. Despite some winterkill, particularly in Italian ryegrass, seed and forage yields were adequate in post‐establishment growing seasons. Seed yield for Italian ryegrass was greatest (1270 kg ha^?1) when it was sown into cultivated soil in mid‐August and least (890 kg ha^?1) when sown alone in May. Italian ryegrass yielded 15–17 % more seed when plots were established in mid‐August rather than in mid‐May or early September. Italian ryegrass cv. Lemtal had a greater density of fertile tillers (1030 m^?2) in the sward than cv. Ajax (860 m^?2) and its tiller density was greater when seeded into cultivated soil in September than in mid‐August. There were fewer spikelets per seed head for sowing Italian ryegrass with barley in May than for the other methods of establishment. Forage yield in regrowth was greater for Italian ryegrass cv. Ajax (2770 kg ha^?1) than for cv. Lemtal (2480 kg ha^?1). Seed yield of perennial ryegrass was greater when seeded in mid‐May than in mid‐August or early September. The seed yield of perennial ryegrass was greater when it was sown with barley in May and harvested for grain, than when it was sown alone or with barley harvested at late milk stage. The establishment methods for mid‐August and early September sowing had little effect on seed yield. However, the no‐till and reduced tillage methods resulted in a greater tiller density than sowing into the cultivated seedbed. Fertile tillers tended to be denser under reduced cultivation for sowing in August. Forage yield of perennial ryegrass regrowth was not influenced by the sowing method and timing. In conclusion, Italian and perennial ryegrasses produce adequate seed and forage regrowth under different establishment methods and timing. However, the poor persistence of Italian ryegrass may limit commercial production after the establishment year in Atlantic Canada.     

Changes over time in the adaptation of barley releases in north-eastern Spain

The objective of this study was to characterize grain yield and adaptation of barley cultivars released in recent decades in north-eastern Spain. Ten six-rowed and 10 two-rowed barley genotypes were grown in eight environments. Mean yields varied among environments between 1.7 and 5.8 tha^?1. New releases showed higher mean yields and were specifically adapted to nonlimiting growing conditions. The average genetic advances were estimated as 40.7 and 32.9 kg ha^?1 years^?1 for two- and six-rowed genotypes, respectively, in the four most productive environments. Old genotypes, with lower overall grain yields, were specifically adapted to the poorer sites. A negative genetic gain, estimated as -14.8kg ha^?1 years^?1. was reorded for six-rowed culiivars in the four poorest sites. No significant association was observed between heading date and year of release. Variations in carbon isotope discrimination (Δ) were examined to assess whether changes in adaptation could be partially explained by shifts in the genoiypic transpiration efficiency (TE) over time, in the most favourable environments, new releases showed the highest grain yields and carbon isotope discrimination values (Δ). By contrast, older cultivars had constitutively? lower Δs and therefore higher TEs. These results suggest a genetic association between low TE and yield potential and specific adaptation to stress-free conditions so that selection for yield under favourable conditions could have resulted in an indirect downward genetic shift in the TE of modern cultivars.     

Crop and Weed Growth in a Sequence of Spring Barley and Winter Wheat Crops Established Together from a Spring Sowing (Relay Cropping)

A relay cropping system of cereals, whereby winter wheat (Triticum aestivum L.) was undersown in two‐row spring barley (Hordeum distichum L.), was established in a field trial in central Sweden in 1999 and continued until 2000. The purpose of the study was to examine crop and weed responses to different plant densities of the undersown winter crop. Winter wheat was sown at four seed rates (187, 94, 47 and 0 kg ha^?1) immediately after the sowing of barley. Barley was harvested in the first autumn after sowing and winter wheat in the second autumn. The grain yield of barley was not affected by the seed rate of wheat, and averaged 4580 kg ha^?1. Winter wheat did not vernalize during the first growing season but remained at the vegetative stage. The grain yield of wheat was 1990 kg ha^?1 for the lowest and 5610 kg ha^?1 for the highest seed rate of wheat. Whilst the undersowing process itself stimulated weed emergence in this experiment, increasing the undersowing seed rate reduced the population of perennial weeds by 40–70 %. In the second growing season, the total biomass of weeds was 66 % higher at the highest seed rate compared with the lowest seed rate.     

Genotypic Variation of Gas Exchange Parameters and Leaf Stable Carbon and Nitrogen Isotopes in Ten Quinoa Cultivars Grown under Drought

Genotypic variations in leaf gas exchange and grain yield were analysed in 10 highland‐adapted quinoa cultivars grown in the field under drought conditions. Trials took place in an arid mountain region of the Northwest of Argentina (Encalilla, Amaicha del Valle, 22°31′S, 65°59′W). Significant changes in leaf gas exchange and grain yield among cultivars were observed. Our data demonstrate that leaf stomatal conductance to water vapour (g_s) is a major determinant of net CO₂ assimilation (A_n) because quinoa cultivars with inherently higher g_s were capable of keeping higher photosynthesis rate. Aboveground dry mass and grain yield significantly varied among cultivars. Significant variations also occurred in chlorophyll, N and P content, photosynthetic nitrogen‐use efficiency (PNUE), specific leaf area (SLA), intrinsic water‐use efficiency (_iWUE) and carboxylation capacity (A_n/C_i). Many cultivars gave promissory grain yields with values higher than 2000 kg ha^?1, reaching for Sayaña cultivar 3855 kg ha^?1. Overall, these data indicate that cultivars, which showed higher photosynthesis and conductances, were also generally more productive. Carbon isotope discrimination (Δ) was positively correlated with the grain yield and negatively with _iWUE, but δ¹⁵N did not show significant correlations. This study provides a reliable measure of specific responses of quinoa cultivars to drought and it may be valuable in breeding programmes.     

Annual Medicago as a Smother Crop in Soybean

Use of conservation tillage and narrow row spacing in soybean [Glycine max (L.) Merr.] production has led to increased use of herbicides for weed control. Some producers are seeking alternative weed control methods, such as smother crops, that would reduce dependence on chemical weed control. A successful smother crop must compete strongly with weeds but minimally with the crop. In four environments, we intercropped three annual Medicago spp. (medics) with soybean to test their utility as a smother crop for weed control. Annual medics were intercropped with soybean at rates of 0, 85, 258, or 775 seeds m^?2, and the intercrops were grown with and without weed control. Increasing medic seeding rate decreased weed yields but also reduced soybean herbage and grain yields. For the weed‐controlled treatment, average soybean grain yields declined 7 kg ha^?1 for every 10 seeds m^?2 increase in medic seeding rate. Soybean grain yield was lower when grown with Medicago scutellata L. cv. Sava than when grown with Medicago polymorpha L. cv. Santiago or Medicago lupilina L. cv. George. Soybean grain yield was negatively related (r=?81) to medic herbage production. In the autumn following soybean harvest, medic residue ranged from 200 to 3700 kg ha^?1 depending on the location and seeding rate. Medics provided residue for soil protection, suppressed weeds, but also reduced soybean yields.     

Effect of Organic and Inorganic Nutrients for Soil Quality Conservation and Yield of Rainfed Low Land Rice in Sub-tropical Plateau Region

The effect of organic sources of nutrients and inorganic fertilizers, was studied on grain yield of lowland rice and some aspect of soil quality parameters in a field experiment at Agricultural Experimental Farm of Indian Statistical Institute, Giridih, situated at eastern plateau region of India, during consecutive years 1997–2002. Chemical fertilizers and various organic matters were applied to two rice cultivars, Sabita and Subarna. The highest mean grain yield was 3.53 t ha^?1 and maximum agronomic efficiency was 60.3 % with the application of inorganic fertilizer followed by cow dung, where 3.47 t ha^?1 grain yield was recorded with an agronomic efficiency of 57.5 %. Grain yield of rice recorded under organic sources of nutrients was not significantly different from that of inorganic fertilization though there was improvement in soil quality parameters under organic sources. Soil organic carbon (0.72 %), microbial biomass‐C (279.23 μg g^?1 dry soil), urease activity with buffer (33.54 μg urea hydrolyzed g^?1 oven‐dry soil) and non‐buffer (21.97 μg urea hydrolyzed g^?1 of oven‐dry soil) methods and acid phosphatase activity (2.24 μg para‐nitrophenol released g^?1 of oven‐dry soil) analysed following the harvest of the crop were highest under cow dung manure treatment; the most efficient organic source under the experiment. Mean grain yield of rice was significantly higher in Sabita cultivar over Subarna. The regression analyses among the variables have shown that there was linear relationship among soil parameters and grain yield of rice.     

Effect of Phosphorus and Nitrogen Fertilization on Sunflower (Helianthus annus L.) Nitrogen Uptake and Yield

Little is known about the effect of combined phosphorus and nitrogen (P‐N) fertilization on the N requirement of sunflower (Helianthus annus L.). This study was carried out to evaluate the effects of varying levels of P and N, as well as the interaction P × N, on the N uptake, yield and N apparent utilization efficiency under field conditions. Split‐plot design experiments were conducted in the mid‐western Pampas in Argentina. Four levels of N (0, 46, 92 and 138 kg N ha^?1) and three levels of P (0, 12 and 40 kg P ha^?1) were applied to two Typic Hapludolls over two growing seasons (1997–98 and 1998–99). N uptake and soil N‐NO₃ contents were determined at the V₇, R₅ and R₉ growth stages. The sunflower yield ranged from 2.5 to 5.0 Mg ha^?1. The total N requirement was around 45 kg N Mg^?1 grain, and this result suggests that it is not necessary to use different N requirements (parameter b) for fertilized crops when a yield response is expected. To achieve a 100 % yield maximum a N supply (soil plus fertilizer) of 181 kg N ha^?1 at P₄₀ was needed. However, at P₀, the highest yield was about 80 % of the maximum yield with a N supply (soil plus fertilizer) of 164 kg N ha^?1. P application increased the apparent use efficiency of the supplied N.     

Analysis of Water Non-limiting and Water Limiting Yields and Yield Gaps of Groundnut in India Using CROPGRO-Peanut Model

To assess the scope for enhancing productivity of groundnut (Arachis hypogaea L.) in India, well‐calibrated and validated CROPGRO‐Peanut model was used to assess potential yields (water non‐limiting and water limiting) and yield gaps of groundnut for 18 locations representing major groundnut growing regions of India. The average simulated water non‐limiting pod yield of groundnut for the locations was 5440 kg ha^?1, whereas the water limiting yield was 2750 kg ha^?1 indicating a 49 % reduction in yield because of deficit soil moisture conditions. As against this, the actual pod yields of the locations averaged 1020 kg ha^?1, which was 4420 and 1730 kg ha^?1 less than the simulated water non‐limiting and water limiting yields, respectively. Across locations, the simulated water non‐limiting yields were less variable than water limited and actual yields, and strongly correlated with solar radiation during the crop season (R² = 0.62, P ≤ 0.01). Simulated water limiting yield showed a significant positive, but curvilinear relationship (R² = 0.73, P ≤ 0.01) with mean crop season rainfall across locations. The relationship between actual yield and the mean crop season rainfall across locations was not significant, whereas across seasons for some of the locations, the association was found to be significant. Total yield gap (water non‐limiting minus actual yields) ranged from 3100 to 5570 kg ha^?1, and remained more or less unaffected by the quantity of rainfall received across locations. The gap between simulated water non‐limiting and water limiting yields, which ranged from 710 to 5430 kg ha^?1, was large at locations with low crop season rainfall, and narrowed down at locations with increasing quantum of crop season rainfall. On the other hand, the gap between simulated water limiting yield and actual farmers yield ranged from 0 to 3150 kg ha^?1. It was narrow at locations with low crop season rainfall and increased considerably at locations with increasing amounts of rainfall indicating that type of interventions to abridge the yield gap will vary with the rainfall regimes. It is suggested that improved agronomic management (such as high yielding cultivars, balance crop nutrition and control of pest and diseases) in high rainfall regimes and rainfall conservation and supplemental irrigations in low rainfall regimes will be essential components of the improved technologies aimed at abridging the yield gaps of groundnut.     

Optimierung der Produktion von Wintergetreide zur Bioethanolherstellung durch unterschiedlich intensive Anbauverfahren

The investigations were based on biennial field trials carried out at two locations comprising the factors location/previous crop, winter cereal genotype (rye cv. ‘Farino’,triticale cv. ‘Modus’, wheat cv. ‘Batis’) and production intensity level. One agronomical focus was to replace the mineral N‐supply due to its energetic relevance, by either the residues of legumes, or stillage, a processing residue containing organic N. The measurement included the crop yield ha^?1, the bioethanol exploitation dt^?1 and the bioethanol yield ha^?1. The last was closely correlated to the grain yield and thus dominated by intensity level. Highest bioethanol yields with an average peak at 4022 l ha^?1, always occurred at the highest intensity level. Bioethanol exploitation however, was mainly determined by the genotype. The cultivars showed significant exploitation and yield differences. An adequate bioethanol exploitation was observed with the wheat cv. Batis in contrast to diminished grain and bioethanol yields. Considering bioethanol exploitation and bioethanol yield, the triticale cv. Modus was the outstanding genotype. Despite high grain yields, the bioethanol yields of the rye cv. Farino stayed mean, because of a genotypic lowered bioethanol exploitation. Comparing the approaches of mineral nitrogen substitution, legume N was successful, whereas stillage fertilizing, according to the examined conditions, resulted in ample decreased grain and bioethanol yields ha^?1.     

Wheat Cultivars Adapted to Post-Heading High Temperature Stress

The existence of genetic variation in wheat for tolerance to high temperature stress has been reported but cultivars released for a particular production system often are not characterized. The objective of this study was to identify and describe the characteristics of wheat cultivars adapted to production systems with risks of high temperature during the post‐heading period. Fifteen diverse wheat cultivars and one unreleased genotype were evaluated at the Texas A&M University Agricultural Research and Extension Center, Uvalde, TX, during two seasons characterized by daily maximum temperatures as high as 36 °C. Measurements during both seasons included days to heading, days to physiological maturity and grain yield. Large and significant (P < 0.05) grain yield differences were measured among cultivars within each season. Yield varied between 2979 and 4671 kg ha^?1 in the first season and between 1916 and 5200 kg ha^?1 in the second season. Late planting in the second season delayed heading date resulting in the post‐heading period to coincide with periods of high temperatures. Cultivars that headed early, in general, yielded better than cultivars that headed later within each season with yield reduction of 35.3 kg ha^?1 in the first season and 91.0 kg ha^?1 in the second season for every 1 day delay in heading after mid‐March. Early‐heading cultivars outperformed later‐heading cultivars because of two distinct advantages: the early‐heading cultivars had longer post‐heading and, therefore, longer grain filling period than the later‐heading cultivars. In addition, early‐heading cultivars completed a greater fraction of the grain filling earlier in the season when air temperatures were lower and generally more favourable. The advantage of earlier‐heading cultivars was also manifested in the amount of green leaves retained to anthesis. Earlier‐heading cultivars produced fewer total leaves per tiller but retained more green leaves and lost fewer leaves to senescence at anthesis than later‐heading cultivars. The results suggest that early heading is an important and effective single trait defining wheat cultivars adapted to production systems prone to high temperature stress during the post‐heading period.     

Agronomic performance of winter wheat grown under highly divergent soil moisture conditions in rainfed and water‐managed environments

Even in the temperate climates of Europe, increasing early season drought and rising air temperature are presenting new challenges to farmers and wheat breeders. Sixteen winter wheat (Triticum aestivum L.) genotypes consisting of three hybrids, six line cultivars and two breeding lines from Germany as well as five line cultivars from France, Austria, Slovakia, Hungary and the Ukraine (referred to as “exotic” lines) have been included in this study. The genetic materials were evaluated over three growing seasons under a range of soil moisture regimes at the three North German sites Braunschweig (irrigated and drought‐stressed), Warmse (rainfed) and Söllingen (rainfed). The average grain yields in the twelve growth environments (water regime × season combinations) ranged from 6.1 to 13.5 t ha^?1. The exotic lines showed little evidence of specific phenological adaptation to drought although they are frequently faced with water scarcity in their countries of origin. The hybrids and German lines exhibited higher regression coefficients (b_i) to environmental means than the exotic lines, indicating particular adaptation to favourable growing conditions. The phenotypical correlations of grain yield between the various environments were high, ranging for instance from 0.6 to 0.8 for the irrigated and drought‐stressed environments at Braunschweig. It is thus expected that in the foreseeable future continued selection aiming at high yield potential will suffice as a means to counter the expected increase in droughts.     

Effects of Row Spacing, Support Plant Species and Support Plant Mixture Ratio on Seed Yield and Yield Characteristics of Hungarian Vetch (Vicia pannonica Crantz)

The effects of row spacing (17.5 or 35.0 cm), support plant species (barley or triticale) and the proportion of crops in mixtures (no support plant or support plant 20, 40 or 60 %, respectively) on the seed yield and yield characteristics of Hungarian vetch (Vicia pannonica Crantz) were investigated. Increasing the row spacing increased the seed yield of V. pannonica from 881.0 to 1248.0 kg ha^?1. On average, in a pure stand the seed yield of V. pannonica was 1141.0 kg ha^?1. In mixtures with barley and triticale, the seed yield of V. pannonica averaged 986.0 and 1143.0 kg ha^?1, respectively. In single mixed stands the seed yield of V. pannonica varied between 551.0 kg ha^?1 (60 % support plant barley) and 1603.0 kg ha^?1 (20 % support plant triticale). The yield advantage of V. pannonica in this triticale mixture was 40 % compared to the V. pannonica pure stand. With respect to the total yield in the mixture with 20 % triticale (1902.0 kg ha^?1) the yield advantage over the V. pannonica pure stand was as high as 65.1 %. In the mixed stands the number of seeds per pod and the thousand‐seed weight of V. pannonica were higher than in V. pannonica pure stands.     

Productivity of Bahiagrass Pastures in South-western Japan: Synthesis of Data from Grazing Trials

This study examined the rate of herbage production and herbage quality of bahiagrass (Paspalum notatum Flügge) using data from five grazing trials in the low‐altitude region of Kyushu, south‐western Japan, in an effort to (a) evaluate productivity of bahiagrass pastures, (b) analyse its relationship to meteorological, vegetational and managerial variables, and (c) obtain implications for better management of bahiagrass pastures. The rate of herbage production, ranging from ?56 to 213 kg DM ha^?1 day^?1, tended to increase from spring (April–May) to mid‐summer (July) and decrease thereafter. The rate was expressed by a multiple regression equation where nitrogen fertilizer rate, air temperature, rainfall and herbage mass had positive effects. Dry matter digestibility (DMD) and crude protein (CP) concentration of herbage were in the range of 471–727 and 84–161 g kg^?1 DM respectively. DMD was expressed by a regression equation where the day number from 1 April and herbage mass had negative effects, and the sampling height and nitrogen rate had positive effects. CP concentration was expressed by an equation showing a positive effect of nitrogen rate and a negative effect of herbage mass. The results indicate that management of bahiagrass pastures should aim at maintaining herbage mass closely above the critical level below which intake by grazing animals is restricted, in order to increase quality and ensure quantity. This is particularly important when nitrogen fertilizer is applied.