ALBERT

Description: SUMMARYThe effects of chlormequat chloride on grain yield and its components in spring barley (Hordeum vulgare)cultivars were studied in five field experiments conducted at two sites near Belfast over 3 years (1982–84). Grain yield was significantly increased by chlormequat chloride treatment in only one experiment, where ear loss was less in the treated plots. Number of ears per plant was increased by treatment in another experiment but yield was unaffected. It was concluded that chlormequat chloride applications are unlikely to produce consistent yield increases in field crops of spring barley.

Description: SUMMARYWinter wheat cultivars Apollo, Hornet, Longbow and Norman were each sown at 50, 100, 200, 400, 800 and 1600 seeds/m2 in a field experiment conducted in Northern Ireland over the 1989/90 crop year. No growth regulators were applied and the wheat received 178 kgN/ha top-dressing in the spring. Hourly rainfall, windspeed and wind direction data were recorded and lodging was visually assessed from the end of May to harvest. Lodging first occurred in the 1600 seed-rate plots as the ears were emerging in early June and then progressively increased in the 800, 400 and 200 plots during June, July and August. Lodging did not occur suddenly but took several hours, with the stems first lying at an angle before lodging completely. Stem buckling or breakage did not appear to be the principal form of structural failure. The longest strawed cultivar, Longbow, lodged most severely. The shorter-strawed Norman also lodged badly in contrast with Hornet which had a similar straw length. Apollo, which was taller than Norman and Hornet and produced more ears per square metre than the other cultivars, lodged least but tended to lean at c. 30° from the vertical. Lodging occurred during or within 24 h of periods of rainfall which, in many cases, coincided with windspeeds at crop height averaging 〉 25 km/h and occasionally 〉 50 km/h. Lodging also occurred following rainfall when the windspeed did not exceed 16 km/h. The grain yield was negatively correlated with the average lodging from ear emergence to harvest, there being a 1 t/ha decline in yield for each 10% increase in average area lodged. The 50 and 100 seed-rate plots yielded 10 t/ha and had little or no lodging. The decline in yield with increased lodging and seed rate was attributed to the effect of lodging rather than to seed rate and was associated with a fall in the number of grains/ear and 1000-grain weight from 56 and 53·5 g at the lowest seed rate to 15 and 42·7 g at the highest, respectively. A comparison of the plants from lodged and unlodged plots of the 1600 and 800 seed rates, and subsequently of the 800 and 400 seed rates, indicated that at the higher seed rate, lodged plots had less fresh weight per unit area, basal internodes with smaller diameters, fewer support roots per stem, and a lower root dry weight per stem.

Description: Ease of removal of the husk of oats from its enclosed kernel, hullability, affects the efficiency with which oats are milled. Hullability of a range of oat varieties was examined using a mechanical dehuller from autumn-sown trials in Northern Ireland, 1996–98, and in the Republic of Ireland, 1997–98. Varieties differed greatly in hullability, the spring variety, Barra, having good hullability while the winter variety, Gerald, had poor hullability. Differences between the varieties were largely consistent from site to site and from year to year despite large differences in the amounts of grain remaining unhulled from trial to trial. Although secondary grains were easier to dehull than primary grains, differences in the structure of the grain populations did not explain variation in hullability of the varieties. This study highlights the need for an investigation of the effects of agronomic factors on hullability.

Description: Yield, straw length, ripening, damage, grain composition and quality were determined on seven winter oat varieties included in trials grown in Northern Ireland between 1990 and 2000. Three management regimes were applied to the varieties in each year: (1) with fungicide but without plant growth regulator applications (+F−PGR); (2) with plant growth regulator and fungicide applications (+F+PGR); and (3) with neither fungicide nor plant growth regulator applications (−F−PGR). Disease control significantly improved yield, kernel content and the proportions of groats above 2·0- and 2·2-mm sieves but delayed ripening and increased the content of free kernels. Application of chlormequat significantly reduced straw length and the content of empty husks and increased the content of good oats but reduced kernel content. Specific weight, grain weight and the proportions of grain above 2·0- and 2·2-mm sieves were not significantly affected by either control of disease or application of chlormequat.The combined effects of disease control and chlormequat significantly reduced leaning and brackling while lodging was reduced but not significantly. Rather than an increased incidence following disease control which was reduced by application of chlormequat, the two management strategies resulted in similar small incremental reductions in straw damage. In years with severe straw damage lower specific weight, grain weight and kernel content may have been attributable to the damage but quality was also poor in some years when there was little damage. Grain and groat size were only poor in those years when severe lodging or brackling occurred.Year had the greatest influence on most characteristics and variety to a lesser extent. Disease control and to a lesser extent chlormequat application had smaller effects on fewer characteristics. While the effect of disease control on yield is of economic significance, the effect of chlormequat appears to be mainly of psychological significance.

Description: Outcomes of developmental yield formation processes in oats, namely number of panicles/m2, number of grains/panicle, mean grain weight and incidences of aborted and tertiary grains, were measured in a series of experiments in Northern Ireland and the Republic of Ireland in 1997/98 and 1998/99. Seed rate (200 and 300 seeds/m2), nitrogen (0–200 kg/ha) and plant growth regulator (chlormequat chloride) treatments were applied to the spring oat varieties Aberglen and Barra in one spring- and two autumn-sown experiments, and to the winter varieties Gerald and Image in one autumn-sown experiment. Large variation in number of panicles/m2 and grains/panicle was observed between the experiments and varieties and in response to seed rate, with number of grains/panicle generally being inversely related to number of panicles/m2. At the higher rates of nitrogen rate both number of panicles/m2 and grains per panicle increased. Mean grain weights were relatively constant and were largely determined by variety. Chlormequat chloride had relatively little effect on the yield components, the most consistent being small reductions in mean grain weight.Tertiary grains occurred rarely in the varieties and agronomic treatments used in the programme but were more frequent at higher rates of nitrogen in most of the experiments. Numbers of aborted grains were usually higher where grain numbers were higher although the effects of variety, seed rate and nitrogen on aborted grains were not consistent. Structure of the grain population, i.e. the relative proportions of primary and secondary grain, was stable despite the large differences in number of panicles/m2, spikelet numbers and mean grain weight.The greater yield and growth enhancing effects of nitrogen compared with seed rate and plant growth regulator were apparent in responses by developmental processes active later in the life cycle, namely production of tertiary grains and grain filling.Wide variation in number of panicles/m2 (c. 200–450) and number of grains/panicle (c. 55–145) produced in the crops grown under a very full expression of agro-ecological conditions in this programme was accompanied by small variation in mean grain weight (c. 38–47 mg/primary grain and c. 22–29 mg/secondary grain) and in numbers of tertiary (

Description: SUMMARYA detailed study of nitrogen use efficiency (NUE) and its components in three cultivars of winter wheat, Hereward, Rialto and Riband was undertaken in cultivar trials conducted in Northern Ireland in 1998 and 1999. Yield, grain N concentration, harvest index (HI), nitrogen harvest index (NHI), N uptake efficiency (NUpE), total N uptake, grain N off-take, N utilization efficiency (NUtE) and NUE itself all showed significant variation between sites. Cvars Hereward and Rialto had similar mean values across all the sites for many of the characteristics, with Riband usually differing. In all but one characteristic, grain N concentration, the responses of the three cultivars varied significantly from trial to trial and this, along with the substantial variation between sites, indicates that genetic control of the characteristics is partial. The amount of N applied as fertilizer accounted for little of the variation among the trials with weak associations for NUpE, which decreased, and grain yield, which increased with increasing fertilizer N. Neither grain yield nor NUE was associated with the amount of N taken up by the crop, but grain N concentration increased and NUtE decreased significantly. HI and NHI differed significantly among the cultivars, diverging at higher N uptakes, with Hereward and Rialto being similar and distinctly different from Riband. Grain yield was only weakly associated with NUpE but was strongly and positively associated with NUtE and NUE. The strong negative association between NUtE and NUpE highlights the potential and the urgency of understanding factors influencing uptake of nitrogen by crops. The extent of the non-genetic, i.e. environmental and management, variation in the characteristics, along with the relative similarity of the cultivar means, throws up a challenge to plant breeders, agronomists and researchers wishing to improve NUE genetically and through management. As with yield and other characteristics, a large number of trials will be required to identify consistent differences in NUE among cultivars. Thus, while mechanisms underlying NUE, NUpE and NUtE need to be understood, the possibility of using the HGCA UK Recommended List database to investigate NUE and identify cultivars with improved NUE should also be considered. Since in each of the HGCA trials cultivars have access to the same available N, and since grain yield=available N×NUE, grain yield itself is a surrogate for the NUE of cultivars. Grain N concentration is only determined in a few cultivars at present but could be used as an indicator of optimal N availability in individual trials, allowing variation in NUE of cultivars in response to agro-ecological factors on NUE to be studied.

Description: SUMMARYApplications of nitrogen and a plant growth regulator (mepiquat chloride and ethephon) were used to manipulate stem structure and induce differing degrees of damage due to leaning and lodging in six cultivars of winter barley grown in Belfast, UK, in 1986/87. Weighted incidences of leaning and lodging were combined to give an index indicating damage susceptibility of the cultivars. The index was very high (70) in Pipkin and ranged between 1 and 18 in the other cultivars. Differences between cultivars in number of internodes, plant height and stem weight did not explain their differences in resistance to damage. However, dry weight per unit length ranged from 2·35 and 2·34 mg/mm in the strongest cultivars, Panda and Jennifer, respectively, to 1·75 mg/mm in the weakest cultivar, Pipkin.Nitrogen application increased plant height but did not affect dry weight/main stem, so that dry weight/unit length of stem decreased. The growth regulator treatments reduced plant height and although dry weight/stem did not decrease significantly, dry weight/unit length of stem was similar in treated and untreated plots.Dry weight/unit length has potential as an objective indicator of straw strength in winter barley cultivars and could be used in cultivar evaluation in the absence of damage in field trials.

Description: The physical parameters of oats of prime importance in determining milling quality are kernel content, the content of free kernels, hullability and screenings. In addition to screenings, hectolitre weight is used in the commercial trading of grain as an indicator of quality due to the absence of suitable methods, for commercial use, for determining the parameters that are closely related to milling quality. The effects of nitrogen (0–200 kg/ha), seed rate (200 and 300 seeds/m2) and plant growth regulator, chlormequat chloride, on grain quality were investigated at two locations, in one spring and three autumn sown experiments, in 1997/98 and 1998/99. Yields increased at higher rates of nitrogen and at the higher seed rate but were not significantly affected by chlormequat chloride. The effects of nitrogen rate and seed rate on kernel content were inconsistent but overall there was a small reduction at the higher nitrogen and higher seed rates and where chlormequat chloride was applied. In general, free kernels were reduced at the higher rates of nitrogen, at the higher seed rate and where chlormequat chloride was applied. Hullability improved at higher rates of nitrogen but was poorer at the higher seed rate and with chlormequat chloride. Screenings increased and hectolitre weight declined at the higher rates of nitrogen, the higher seed rate and with chlormequat chloride. The decline in hectolitre weight due to treatments within each experiment in general was associated with reductions in kernel content, content of free kernels and an increase in screenings. However, variation in hectolitre weight did not reflect variation in kernel content, free kernels and screenings between experiments. Overall, the changes in quality due to nitrogen rate, seed rate and chlormequat chloride were small compared with differences between varieties.

Description: SUMMARYThe requirement for inorganic fertilizer nitrogen (N) by winter wheat crops in the United Kingdom is derived using the Department for Environment, Food and Rural Affairs (Defra) Fertilizer Manual. In the experimental programme described and discussed in the present paper, the appropriateness of these recommendations for winter wheat grown in Northern Ireland is examined.Yield response to N varied in experiments conducted on two winter wheat cultivars (cvars) in Northern Ireland from 2007 to 2009. Consequently the optimum N rate (Nopt, defined as the rate of applied N where the value of the increase in yield equals the cost of the increment in fertilizer applied and beyond which additional N would not repay its cost) also varied from year to year. The band of fertilizer N rates over which margins were reduced by £20 (GBP) and £50 also varied from year to year. Changes in the N:grain price ratio affected Nopt to differing extents in the three experiments depending on the shape of the yield v. N response.Nopt should therefore be considered as a range of N rates because (1) it varies from year to year and probably also field to field and (2) the margin of income from grain over cost of fertilizer varies little over a range of N rates because of the shape of the asymptotic response of yield to N. Alternatively, in high rainfall areas (annual rainfall 〉700 mm) of England, Wales and Northern Ireland, where Table C of the Fertilizer Manual (formerly RB 209) is used to determine soil nitrogen supply (SNS) index, a single N rate could be adopted at SNS indices of 2 or less (equating to soil N supplies of 100 kg/ha or less). A rate of 240 kg N/ha could be adopted based on the over-years function fitted to all results in the three experiments reported in the present paper and including treatments that vary in the splitting of N applied between the two applications and in their timing.Grain N concentration rarely exceeded the guideline 19 mg/g for feed wheat crops identified in the Fertilizer Manual (Anon. 2010). Overall, N taken up by the crops was used efficiently, and particularly so at lower N rates. However, at low fertilizer N rates the contribution from ‘free’ soil N inflates the ‘apparent’ value of grain yield produced. The responses of yield and grain N concentration to N show that crop processes work to maximize yield at the expense of N concentration in the grain. Therefore there is less need to be concerned about identifying the optimum N rate and predicting fertilizer N requirement with a high degree of precision. Instead growers could assess and adjust the efficiency of their N use based on grain N concentration generally, rather than specifically assess whether their fertilizer N applications were close to Nopt. Essentially as grain N concentration increases, yield/kg of applied fertilizer N decreases. Thus at low grain N concentrations, yield could be increased by increasing N applications and at high grain N concentrations yield could be maintained and profitability increased by reducing N applications.

Description: Watson (1937) in his important work on Acanthodians demonstrated that the mode of jaw-suspension of this group and probably also that of the Arthrodira.Macropetalichthyida, Rhenanida, and Antiarchi was in a more primitive condition than in other Gnathostomes. The hyomandibula of these fishes played no important part in the suspension of the jaws, and the hyoidean gill-slit persisted as such, not being reduced to a spiracle. Watson introduced the name Aphetohyoidea (free hyoid) for the group containing all these fishes, distinguishing them from the more advanced Chondrichthyes and Osteichthyes.