ALBERT

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: 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: 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: Factorial experiments were carried out on spring- and winter-sown oat crops in Ireland in 2016–2019 to identify plant responses in yield formation and grain filling procedures. Two cultivars (Husky and Keely), three seed rates (250, 350 and 450 seeds/m2), six applied nitrogen (N) rates (40, 70, 100, 130, 160 and 190 kg N/ha) with a plant growth regulator (PGR) were examined in spring and winter sowings, using the same cultivars at five rates of applied N (80, 110, 140, 170 and 200 kg N/ha). The applied N rate and seed rate significantly (P 〈 0.05) modified the yield components determining grains/m2 in spring- and winter-sown crops with increases in panicle number of key importance. Increases were also observed in the proportion of primary grain by weight (0.9–1.6%) and number (0.7–1.4%) ratios in spring-sown crops in response to applied N rate, with winter-sown crops exhibiting a more consistent pattern of grain fill. Seed rate and PGR application had minor effects on yield components and panicle conformation. Grain fill procedures played an important role in the maximization of grain yield under seasonal conditions. Significant positive correlations were observed between the number of aborted grain sites and yield under drought conditions (0.22), with negative associations observed in near-optimal conditions (−0.22 to −0.41). Agronomic effects on grain site abortion were minimal in comparison with seasonal effects. In seasons characterized by cool, consistent conditions, grain yield was maximized by the utilization of all available grain sites. Where assimilate shortages were encountered during grain fill the abortion of grains sites was positively associated with grain yield.