P. D. Hebblethwaite

The effects of water stress on the growth, development and yield of Vicia faba L.

Many workers have recorded large reductions in yield due to water stress, and substantial responses to irrigation in faba bean (2) (30) (15) (27) (28) (40) (32) (7) (19) (34) (21).

Lodging studies in Lolium perenne grown for seed: 2. floret site utilization

In these experiments lodging not only decreased the number of seeds harvested, but also had an effect in determining which spikelets on the ear set most seed. These data have also shown that many more seeds are set than are harvested, even when the crop is not lodged. It is suggested that there is a lack of assimilate supply to fill the developing seeds, some of which abort, allowing the remainder to attain a viable seed weight. Mechanical support of the crop may increase the assimilate supply to the seed thus allowing seed further up the ear and spikelet to develop fully.

Comparison of the effects of autumn and spring sowing date on growth and yield of combining peas ( Pisum sativutn L.)

Experiments 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.

Factors influencing disease resistance in high and low tannin Vicia faba

The in vitro resistance of five white and four coloured-flowered lines and cultivars of Vicia faba to seed and root inoculation with spore suspensions of the pathogenic soil-borne fungi, Fusarium culmorum and Pythium debaryanum, was investigated under aseptic conditions in the UK. The presence of foliar diseases was also assessed in the field in 1989/90. White-flowered lines were more susceptible than coloured genotypes to fungal infection during germination but equally resistant during seedling growth. High-tannin containing seed coats had chemical and physical properties which protected seeds against fungal infection during germination. Frequent cracking of the seed coat in a zero-tannin line was associated with a greater fungal contamination of seeds. Resistance to the foliar diseases Uromyces viciae-fabae and Botrytis fabae was not related to flower colour. The results are discussed in relation to emergence in white-flowered types.

Effect of different inter-row spacings on faba beans of different form

Abstract Plants with different morphologies may exploit the space available to them more or less effectively. Differences in inter-plant competition were examined in a field trial with determinate and semi-determinate varieties of faba bean (Vicia faba L.; cv.s Ticol and Alfred, respectively) grown at three different inter-row widths. Plant mortality was greater in Alfred than in Ticol and especially at the widest inter-row spacings (47.6 cm). The smaller size of the determinate forms and their ability to branch may enable them to more effectively exploit the aerial environment, particularly at wider inter-row spacings. Alfred yielded more than Ticol, which was attributed to both a greater leaf-area duration and a greater ability to transfer assimilates from the stem to the pods during grain growth. Different inter-row widths had no effect on yield, although the numbers of stems, pod-bearing nodes, pods and seeds per unit area were reduced by wide inter-row spacings. The practical signficances of this in terms of weed control and intercropping is discussed.

Yield production in two contrasting forms of spring-sown faba bean in relation to water supply

Abstract The production and grain yield of a semi-determinate (Minica) and a determinate variety (Ticol) of spring-sown faba bean were compared under five different irrigation treatments during 1986 and 1987 at the University of Nottingham. Although the number of reproductive structures (flowers and pods) was greater in Ticol than in Minica, grain yields were greater in Minica. The harvest index increased less rapidly in Ticol than in Minica for each increase in total dry matter. However, in both varieties grain yield was proportional to dry matter production which was greater in Minica. Since this proportionality was unaffected by irrigation treatment it was concluded that neither variety had a particular moisture-sensitive growth phase. Lower crop growth rates in Ticol than in Minica under non-irrigated conditions suggest that Ticol may be more susceptible to water stress than Minica.

Effects of plant population density on spring-sown field beans (Vicia faba) with different growth habits

Determinate 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/m 2 . 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.

Precision drilling combining peas ( Pisum sativum L.) of contrasting leaf types at varying densities

Field experiments were conducted in 1983–4 to investigate the effect of precision drilling and plant density on establishment, growth, radiation interception and yield of combining peas of varying leaf phenotype (Varieties ‘Birte’, leafed; ‘Filby’, leafless; and ‘BS3’, semi-leafless). Precision drilling established a more uniform plant distribution than oyjord drilling; visual differences observed soon after emergence were not observed at flowering. Precision drilling resulted in more radiation interception early in the season for semi-leafless but not leafed peas; dry-matter production and photosynthetic area index (PAI) were not increased. Yield data indicated that precision drilling produced similar yields to oyjord drilling at similar densities. Increasing plant density increased radiation interception, dry-matter production and PAI during vegetative growth; density treatment effects were less marked post-flowering. Pea leaf phenotypes differed in their yield response to increasing density. Radiation interception was related to dry-matter production and PAI to obtain an estimate of photosynthetic efficiency (e) and the attenuation coefficient ( k ), respectively, e and k were constant irrespective of spatial arrangement, leaf phenotype and plant density. The relative importance of spatial arrangement and plant density in increasing radiation interception and PAI and influence on yield is discussed; other potential agronomic advantages of precision drilling are described.

Effects of plant population density on determinate and indeterminate forms of winter field beans (Vicia faba). 1. Yield and yield components

Using an indeterminate cultivar, Bourdon, and a determinate selection, 858 (provided by Plant Breeding International, Cambridge), of winter field bean, the effect of plant population density on yield was investigated in field trials at the University of Nottingham at Sutton Bonington in three consecutive seasons beginning in 1985/86. Plant morphology had no effect on the optimum plant density, which for both entries lay between 10 and 20 plants/m 2 . Bourdon yielded significantly more (2 t/ha, on average) than 858 and this was attributable to more pods/pod-bearing stem, more seeds/pod and heavier seeds. Selection 858 was also less winter hardy. Yield was most closely correlated with number of seeds/plant, but other components were almost as important, highlighting the plasticity of yield in Vicia faba and the difficulties in attempting to increase yield by selecting for particular components of yield. In contrast to spring beans, the indeterminate cultivar of winter field bean produced as many branches as the determinate entry and both produced fewer branches at higher densities. There was no difference between the two growth habits in the relative contribution of each stem class to the yield of the whole plant. Higher-order branches contributed less than the main stem to final yield.

Effects of autumn sowing dates on growth and yield of indeterminate and determinate field beans (Vicia faba).

Determinate 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.