ALBERT

Description: SummaryThe effects of lodging on the seed yield of S. 23 and S. 24 perennial ryegrass were investigated in a series of field experiments from 1973 to 1976. Natural lodging severely reduced seed yield in all years as a result of a decrease in the number of seeds per unit area. Controlled lodging at different stages of crop growth produced more variable results, indicating that lodging may affect both pollination and seed development. Disturbance of the crop during anthesis in order to aid pollination did not improve seed yields, possibly as a result of damage incurred.

Description: SummaryExperiments were conducted between 1978 and 1981 to investigate the effect of autumn and spring sowing on emergence, winter survival, growth and yield of combining peas (varieties ‘Frimas’, ‘Filby’ and ‘Vedette’). Effects of growth regulator PP 333 (Paclobutrazol, ICI pic) application and defoliation on winter survival of Filby were also investigated. Field emergence of autumn-sown Frimas (winter hardy) was less than Vedette or Filby but percentage winter survival was greater. PP 333 application, but not defoliation, increased percentage winter survival of Filby sown in September. Total dry-matter production and photosynthetic area of autumn- compared with spring-sown crops varied considerably between seasons. Yield data indicated that autumn-sown crops produce similar seed yields to spring sowings when winter survival is adequate. November sowings matured 2–4 weeks before March-sown crops, depending on variety and season. Optimum sowing dates were mid-November and early March. Large seed-yield reductions occurred when sowing was delayed until mid-April.

Description: SUMMARYDeterminate forms of field bean (Vicia faba L.), because of their altered growth habit, may differ in phenology from indeterminate cultivars and so their responses to environmental conditions may necessitate different optimum sowing dates. This was studied in autumn-sown field beans at the University of Nottingham at Sutton Bonington by standard growth analysis techniques, final yield components and monitoring of crop growth stages in an indeterminate cultivar, Bourdon, and two determinate populations, 858 and 796 (provided by Plant Breeding International, Cambridge), in three consecutive seasons beginning in 1985/86.Bourdon yielded significantly more (2·4 t/ha, on average) than the determinate selections as a result of more pod-bearing nodes per stem and seeds per pod and a greater individual seed weight. There was, however, no correlation between seed yield and canopy size, either in total or during pod filling. Determinacy, contrary to expectation, did not increase harvest index. In fact, the reproductive stems of Bourdon had higher harvest indices than those of 858. The yield disadvantage of determinates was therefore exacerbated by the existence of reproductive stems, which, by prolonging the maturation phase, may also detract from a further potential benefit of the determinate habit, namely an increase in yield stability.There seemed to be no cultivar differences in the temperature requirement for the initiation of developmental processes. An average accumulation of 1239 °C days was required from sowing to flowering. Differences between this and other work in the calculated base temperature for flowering were cautiously explained by the lack of data distinguishing day and night temperature in this experiment and by the use of autumn-sown rather than spring-sown cultivars. It is also suggested that photoperiod may be important in initiating flowering.Both determinate and indeterminate forms gave the greatest seed yields from the earliest sowing dates.

Description: SUMMARYField trials at the University of Nottingham, UK, in 1979 and 1980 investigated the effect of moisture stress on the growth and yield of the leafless dried pea Filby. In the absence of drought, the crop photosynthetic area was increased and maturity delayed. Seed yield was increased by the production of a greater number of reproductive nodes and a reduced abortion of flowers and pods.In the second season, two sowing dates were also tested. Later sowing reduced the seed yield under the high and low moisture treatments by 14 and 33% respectively, due to an increased abortion of flowers and pods. The high moisture treatment reduced the water use efficiency (WUE) in this season and WUE was lower for the later sown crops, but there was no effect on WUE in the previous season.The seed yield and water use of pot-grown leafless peas were lower than were those of a nearisogenic line of leafed peas. Moisture stress reduced the yield of both phenotypes but the effect on the leafless pea was greater. Moisture stress imposed at flowering reduced yields more than it did at pod filling and there was an additive effect of moisture stress at both times.

Description: SummaryThe effects of maleic hydrazide (MH) and chlorocholine chloride (CCC) on S. 23 perennial ryegrass grown for seed were investigated in a series of field experiments from 1972 to 1974. MH significantly decreased straw length and lodging, but also decreased all yield components, seed yield and germination percentage. All growth stages and harvest date were delayed and the seed production mechanism impaired. CCC had little effect on length of fertile tillers or lodging but seed yield was increased in 1972 and 1973 when the chemical was applied at spikelet initiation. In 1972 an increase in 1000-grain weight and in 1973 small but insignificant increases in numbers of fertile tillers and seeds per spikelet were responsible. This chemical had no visible effects on the growth and development of the crop or on germination percentage of the seed.

Description: SUMMARYThe effects of irrigation and nitrogen on the soil-water regimes developed by S. 23 perennial ryegrass grown for seed were investigated in 1972 and 1974 by neutron scattering. Boots extracted water from a depth of about 105 cm by early May in 1972 and by early April in 1974. Extraction from greater depths was insignificant in both years. Without irrigation the maximum deficit was about 110 mm in both years. Deficits built up rapidly in 1974 but in 1972 were delayed to the end of the growing season. Irrigation limited maximum deficits in the top 35 cm of soil to less than 25 mm whereas without irrigation deficits reached as high as 40 mm in both years.Transpiration from unirrigated grass was close to that calculated from meteorological data in 1972, but in 1974 measured crop transpiration was only about 60 %of the potential throughout the growing season. Roots of grass, whilst undergoing inflorescence initiation, apparently may be impaired in their efficiency of water uptake by deficits as little as 30 mm. For irrigated grass agreement between measured and calculated crop transpiration was poor, principally because of surface run-off. Nitrogen in the absence of irrigation appeared to enhance the rate of crop transpiration in 1972 but comparison with 1974 suggested that this effect was not real. Because of surface run-off resulting in uneven distribution of water, and the restrictions to crop transpiration imposed by limited soil water reserves, actual deficits should be monitored in irrigation experiments rather than relying on estimated values.

Description: SUMMARYDeterminate varieties of Vicia faba are smaller and may require higher plant population densities than their conventional indeterminate counterparts to attain high yields. This hypothesis was examined at the University of Nottingham farm at Sutton Bonington, UK, and at INRA, Dijon, France in 1986 and 1987. The determinate varieties Ticol and TP667 and indeterminate M5.1 and Maris Bead were sown in the spring to give a range of densities of 10–100 plants/m2.Yields generally increased as population density increased. The optimum density for determinate varieties was higher than for indeterminate varieties. Indeterminate varieties yielded more than determinate varieties at all plant densities, perhaps because of their larger canopy. Seed yields were affected by year and location. Greater yields were associated with heavier seeds and more seeds per pod.Although several yield components, when expressed per unit area, were significantly correlated with seed yield, their coefficients of determination were never very large. This confirmed the plasticity of yield in field beans.

Description: SUMMARYIn studies at the University of Nottingham at Sutton Bonington in two consecutive seasons beginning in 1986/87, Bourdon, an indeterminate cultivar, and 858, a determinate selection (provided by Plant Breeding International, Cambridge), were compared under six target plant population densities ranging from 10 to 80 plants/m2.As the season progressed, total dry matter production increased to a maximum and then declined. However, growth rates slowed at pod set because, it is suggested, of the change in the chemical composition of the newly synthesized biomass, from carbohydrate to protein, at that time. Leaf area duration was greater in Bourdon than in 858, especially during pod set, but it bore no relation to seed yield. Specific leaf area was unaffected by competition for light. It is proposed that changes in plant population density affect the competition for assimilates within a plant rather than the competition for light between different plants. Losses of branches and reproductive nodes, with time, are cited as evidence for this. The apparent causes of the lower yield of determinate forms of winter field bean relative to indeterminate forms are discussed.

Description: SUMMARYEarly reports on new, nutritionally superior, white-flowered (zero-tannin) faba bean cultivars indicated that they may show poor emergence under field conditions. The field emergence of 23 winter and spring type white and coloured-flowered lines and cultivars was investigated in relation to fungicidal seed dressing in 1989/1990 and 1990/1991 in the UK. These trials showed no definite emergence problems in white-flowered faba beans, probably because of favourable soil and weather conditions. Further experiments were therefore conducted in relation to emergence under controlled environmental conditions. The emergence of lines near-isogenic except for flower colour (the coloured line SCI v. the white line SWI) was investigated in relation to a range of soil moisture levels (soil water potential (SWP) ranging from −1·02 to 0·0 MPa (waterlogged)) and to three temperatures (22, 12 and 5°C) in a clay loam soil. Emergence was rapid and high at the SWP range from −0·52 to −0·24 MPa in both lines, depending on temperature. Any decrease or increase in SWP beyond this range resulted in a substantial reduction and delay in emergence in both lines. Emergence of SWI was more adversely affected than SCI when the temperature decreased from 22 to 5 °C. The emergence of six winter and six spring lines/cultivars was tested in relation to fungicidal seed dressing using wet soil (-0·06 MPa) at 5 °C under controlled environmental conditions. White-flowered winter lines (WWI, Polar and WD) and the spring line, SWI, had poor emergence (56–85%) compared to coloured types (86–98%). In some lines there was a slight improvement when using a fungicidal seed dressing.

Description: SUMMARYThe effects of irrigation and nitrogen on S. 23 perennial ryegrass grown for seed were investigated in a series of field experiments from 1972 to 1974. Irrigation significantly increased seed yield by 16% in 1972 and 52% in 1974 but had no effect in the wet year of 1973. In 1972 maximum deficit reached 110 mm at the end of July and coincided with anthesis. Consequently the yield response was due to an increase in number of seeds per unit area and no other seed yield component was affected. In 1974 peak deficit also reached about 100 mm but started to build up rapidly very early in the season and had reached 80 mm by the time that the first ears emerged. Consequently the yield response was due to increases in number of fertile tillers, number of seeds per unit area and 1000-seed weight.Irrigation had no significant effect on number of florets or seeds, except in 1974 when percentage of florets which produced seed was increased by 2%.Irrigation had some effect on threshed straw yields, total dry matter, harvest index and total number of tillers but where this occurred the response was much smaller than that of seed yield which indicates that irrigation had greater effects on the reproductive development of the crop than on yield of dry matter and tillering patterns. Increasing the quantity of nitrogen from 0 to 80 kg/ha increased seed yields, all seed yield components except 1000-seed weight, threshed straw yields and total dry matter and number of tillers at most sampling dates. Increasing the quantity of nitrogen from 80 to 160 kg/ha had little further effect on the above components except in 1972 where seed yields were significantly decreased.In 1972 number of florets was increased and percentage of florets which produced seed decreased with increasing quantities of nitrogen.