Field Bean Plants Research Articles

Interactive effects of ozone and carbon dioxide on plant-pollinator interactions and yields in a legume crop

• Increasing greenhouse gas emissions is linked to disruption of ecosystem services. • How ozone and carbon dioxide impact pollination services is not well understood. • We report on the effects of elevated ozone and carbon dioxide on field bean plants. • Elevated ozone reversed the positive effects of enhanced carbon dioxide on yield. Recent studies link increased levels of ozone and carbon dioxide to plant performance and plant-herbivore interactions, but the interactive effects on plant-pollinator interactions and ecosystem services have rarely been studied. Here we experimentally tested whether elevated levels of these two gases alter plant growth, flower visitation, and yield in field bean crop ( Vicia faba : Fabaceae or Leguminosae) using a full-factorial experimental set-up. Plants were exposed to (i) clean air (control), (ii) carbon dioxide-enriched (900 ppm), (iii) ozone-enriched (120 ppb) or (iv) carbon dioxide (900 ppm) + ozone (120 ppb) - enriched treatments. We examined how flower visitation by two widespread bee pollinators, Bombus terrestris and Osmia cornuta , and consequent yields responded to the treatments. Increased carbon dioxide levels enhanced flower visitation by B. terrestris and O. cornuta, while an increase in ozone led to a decline in visitation rates. The seed set of field beans generally increased with flower visitation rates of pollinators, revealing a pollination-mediated effect of the increased greenhouse gas concentrations on plant reproduction. In addition to the pollinator-mediated effect, we found an interactive effect of ozone and carbon dioxide on the seeds set in plants visited by B. terrestris: while increases in carbon dioxide enhanced seed set, increases in ozone generally decreased seed set - overruling the effect of increased carbon dioxide. Our results suggest that negative impacts of high ozone levels on flower visitation and fruit set counteract potential increases of legume crop yields with enhanced carbon dioxide concentrations under future climates.

The Physiological and Biochemical Response of Field Bean (Vicia faba L. (partim)) to Electromagnetic Field Exposure Is Influenced by Seed Age, Light Conditions, and Growth Media

Research interest into the exposure of plants to magnetic fields (MF), including electromagnetic fields (EMF), has increased recently but results often vary depending on factors such as plant species and treatment dose. In this study, we exposed young (one year) and old (four years) field bean (Vicia faba L. (partim)) seeds to EMF (50 Hz, 7 mT) and observed seed germination and seedling growth under different conditions (growth media and light). The results indicated a stimulation by EMF of germination and early root growth of Petri dish-sown old seeds in continuous darkness and inhibition of germination of the pot-sown young seeds under long-day conditions. Root growth of two-week-old seedlings from pot-sown young seeds was stimulated by EMF treatment while their stem growth was inhibited. Some selected biochemical traits were examined, showing specific changes in membrane integrity, amylase activity, H2O2 levels, photosynthetic pigments, and content of the main groups of phytohormones, depending on seed age. The results indicate that priming of field bean seeds with EMF (50 Hz, 7 mT) could be a eustress factor that influences germination, early growth, and cellular activities and could positively influence the ability of field bean plants to grow and develop in more stressful conditions at later stages.

Sequence Diversity of the Nucleoprotein Gene of Peanut bud necrosis virus Isolates from South India

AbstractPeanut bud necrosis virus (PBNV), genus Tospovirus (family Bunyaviridae), is an important virus infecting peanut and other crops in South India. PBNV isolates naturally infecting groundnut, brinjal, tomato, black gram, field bean, cowpea, cotton, jute, taro and Calotropis plants were collected from different regions of South India and characterized. Infection was confirmed by direct antigen‐coating enzyme‐linked immunosorbent assay (DAC‐ELISA) using PBNV‐specific antiserum. The coat protein gene was further amplified using PBNV coat protein‐specific primers. The amplicon (830 bp) was cloned and sequenced; sequence analysis revealed that the N gene shared 93–100% and 95–100% sequence identity with PBNV at the nucleotide and amino acid levels, respectively.

Different Physiological Reactions at Vegetative and Generative Stage of Development of Field Bean Plants Exposed to Flooding and Undergoing Recovery

AbstractPlants at various stages of growth are differentiated in their susceptibility to environmental stresses and possibility of regeneration during recovery period after cessation of stress. The role of antioxidative enzymes in the stabilisation of the physiological state of field bean plants was studied. Catalase, peroxidises activity, and hydrogen peroxide accumulation were determined after 1 and 7 days of flooding and after 1 and 7 days of recovery from flooding. The influence of flooding on plants growth was analysed on the basis of leaf area index (LAI), relative growth rate (RGR) and net assimilation rate (NAR). Changes in antioxidative enzymes caused by flooding applied at vegetative stage were reversible. In generative plants, antioxidative enzymes were activated to a greater extent during recovery period and in contrast to vegetative plants did not attain the control level after that period. The reduction in growth was greater when flooding stress was applied at vegetative stage. Vegetative plants regardless of the stabilisation of antioxidant system were not able to restore the physiological function to attain the optimal growth level after flooding. Probably other injuries caused by flooding had a dominant effect on enzymatic antioxidant changes during stress period.

Potential impact of CO2 leakage from carbon capture and storage systems on field bean (Vicia faba)

Capture and geological storage of carbon dioxide (CO(2)) has been suggested to be essential to reduce emissions to the atmosphere and aid mitigation of global climate change. However, leakage from transport pipelines or carbon capture and storage (CCS) reservoirs may pose risks to vegetation and contribute to rising atmospheric concentrations [CO(2)]. This study examined effects on seedling emergence and growth when field bean plants (Vicia faba cv. Wizard) grown under field conditions were subjected to elevated soil [CO(2)] for 39 days after planting. The strong negative correlation between soil [CO(2)] and [O(2)] during the injection period created a hypoxic soil environment under conditions of elevated soil [CO(2)]. The damaging impact of this treatment became apparent early in the experiment as no seeds exposed to soil [CO(2)] >50% emerged, even after injection was discontinued. Some seeds exposed to soil [CO(2)] <50% produced seedlings, but many did not survive. Seedling emergence and survival in the gassed plots was greatest at [CO(2)] of 5-20%, but root and shoot growth was reduced relative to control plants. Seedling emergence and growth were negatively related to soil [CO(2)] and positively related to [O(2)], although it is not known which was more important in inducing the observed effects. These findings suggest that leakage of CO(2) from transport pipelines or CCS sites may greatly reduce seedling emergence and crop establishment in the vicinity of such infrastructures.

Effects of root flooding and stage of development on the growth and photosynthesis of field bean (Vicia faba L. minor)

Field bean plants were subjected to flooding stress for 7 days, during two stages of development: at the vegetative phase (4-week-old seedlings) and at the generative phase (8-week-old plants). The height of plants, total area of leaves, the number of undamaged leaves, dry plant matter, chlorophyll content, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activity, the maximum quantum yield of PS2 photochemistry (Fv/Fm ratio), the photosynthesis rate (P N) and stomatal conductance (g s) were determined. A strong reduction in stem elongation and leaf area as well as in dry matter production was observed as a result of flooding. The responses from vegetative plants were greater than in generative plants. Waterlogging decreased chlorophyll a and b in leaves, notably at the vegetative stage, and persisted after cessation of flooding. After flooding, photosynthesis was strongly reduced and positively correlated with decreased stomatal conductance. Damage to the photosynthetic apparatus resulted in a lower Fv/Fm especially in young seedlings. In vegetative plants Fv/Fm quickly returned to the control levels after the soil was drained. The results show that an excess of water in the soil limits growth and injures the photosynthetic apparatus in field beans, but that the extent of the injury is strongly age dependent.

First Report of Soybean Rust Caused by Phakopsora pachyrhizi on Phaseolus spp. in Argentina.

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi Syd. & P. Syd., has been reported in Argentina on soybean (Glycine max) and kudzu (Pueraria lobata and Pueraria javanica) since the 2002 growing season (1-4). On 29 May 2006, plants of Phaseolus spp. were found to have tan ASR-like rust lesions on leaves at eight different field plots located in the northwestern province of Salta, Argentina. Growth stages of infected bean plants within plots were between pod setting and physiological maturity. Diagnosis of ASR on bean leaves was performed with a stereoscopic microscope to view rust pustules, and suspected uredinia of P. pachyrhizi were observed, furthermore, typical ASR urediniospores also were also observed at ×400. ELISA and PCR methods gave positive results for ASR. Rust spores from these plants were used to inoculate soybean plants at the V3 growth stage with rust spores from field bean plants produced under greenhouse conditions. Typical ASR tan pustules developed within 21 days of inoculation. Bean rust caused by Uromyces phaseoli also was seen in some of the bean plots but was easily differentiated from ASR because the uredinia were much darker and affected the upper leaves, while the ASR uredinia were lighter and spread from the lower leaves to the upper leaves. This finding is of significance in Argentina because bean is an important crop grown in the northwestern region of the country and is planted approximately 2 months after soybean planting. Given this planting time difference, bean may provide an overwintering host for the survival of ASR spores, thereby providing a green bridge for infection of soybean plants during the following growing season.

Targeted Dispersal of the Aphid Pathogenic Fungus Erynia neoaphidis by the Aphid Predator Coccinella septempunctata

The potential of adult and larval C. septempunctata to vector the aphid-specific entomopathogenic fungus E. neoaphidis was assessed through a series of laboratory and field experiments. The ability of coccinellids to vector conidia from a colony of E. neoaphidis -infected pea aphids, Acyrthosiphon pisum, to a colony of uninfected A. pisum was demonstrated in a laboratory study. Adult coccinellids which had previously foraged on plants infested with different densities of sporulating cadavers (1, 5, 15, 30 cadavers per plant) initiated infection in a proportion of uninfected pea aphids (4, 0, 2 and 8%, respectively) when subsequently allowed to forage on A. pisum infested bean plants. Further laboratory studies demonstrated that fourth instar larvae and adult coccinellids artificially inoculated with conidia initiated infection in 11 and 13% of an A. pisum population in which they foraged, respectively. Furthermore, a proportion of A. pisum placed on bean plants which had previously been foraged on by inoculated larval and adult coccinellids also died from infection (3 and 10% of A. pisum, respectively). However, although coccinellid adults inoculated with conidia initiated infection in 19% of A. pisum, cereal aphids, S. avenae , exposed to the inoculated coccinellids did not become infected. A further laboratory study demonstrated that infection of A. pisum only occurred if inoculated coccinellids were transferred to A. pisum populations immediately post inoculation. However, a proportion of A. pisum placed on bean plants which had been foraged on by inoculated coccinellids transferred 0, 4 and 24 h post inoculation died from infection (9, 3 and 7%, respectively). A field study further demonstrated the potential of coccinellids to vector E. neoaphidis. Single spring sown field bean plants (Long Hoos Experimental Plots, IACRRothamsted Farm) were enclosed within nylon mesh bags and 25 adult A. pisum were added to each bag with one of the following treatments: no further addition (control), coccinellid adult (control), inoculated coccinellid adult, inoculated A. pisum or sporulating A. pisum cadavers. No aphids died of E. neoaphidis in the control treatments; 5, 16 and 33% of aphids were infected with E. neoaphidis on the other treatments, respectively.

The Effect of Seed Vernalization and Irradiation on Growth and Photosynthesis of Field Bean Plants (Vicia faba L. minor) and on Nitrogenase Activity of Root Nodules

The effect of seed vernalization (2–3°C; 36 days) and irradiation intensity during vegetation of field bean upon growth and maximum leaf photosynthesis (Pmax) as well as specific (SNA) and total nitrogenase activity (TNA) of root nodules was investigated. The measurements were performed at the initial stage of pod development of varieties with undetermined (cv. Nadwiśański) and determined (cv. Tibo) growth habit. In comparison with plants in shading, those which grew in full irradiation produced larger leaf area and more dry weight, achieving higher Pmax values. Stimulation of leaf area enlargement and dry weight increase, especially in respect to the dry weight of underground parts had a positive and significant effect upon TNA value. Accumulation of dry weight was higher in vernalized than non‐vernalized plants, but only in the case of cv. Nadwiślański, in full irradiation conditions. In the case of plants grown in poorer irradiation conditions TNA values were about 68 % (cv. Nadwiślański) and 54 % (cv. Tibo) lower, due to significant limitation of root nodules. TNA value of vernalized cv. Nadwiślański plants was 66 % higher in comparison with non‐vernalized plants. However, the effect was visible only in full irradiation conditions, due to simultaneous greater intensity of root nodules production and higher SNA value. A positive effect of vernalization could also be observed in the decrease of a negative correlation between dry weight of root nodules and SNA in both varieties.

Yield of sugar beet, soybean, corn, field bean, and wheat as affected by lime application on alkaline soils

Environmental regulations and limited storage space compel processors to remove spent limestone and not stockpile it on site. This material is often used as a liming material to control pH on acid soils, but in some cases may have to be applied to alkaline soils. This study was undertaken to evaluate the effect of applying sugar beet processing lime on soils with an alkaline solum. Studies were conducted at seven sites representing four soil series. Lime was applied at rates of 0,1.4, 2.8, and 5.6 magnesium (Mg) ha‐1. Sugar beet (Beta vulgaris L.), soybean (Glycine max L.), cora (Zea mays L.), field bean (Phaseolus vulgaris L.), and wheat (Triticum aestivum L.) were used as test crops. Yield of sucrose and roots of sugar beet as well as yield of soybean, corn, field bean, and wheat were not affected by lime application. Manganese (Mn) and zinc (Zn) concentration in leaves of sugar beet and soybean, and whole field bean plants decreased with increasing lime rates. These results show this lime may be applied at rates up to 5 Mg ha‐1 once every three years on these alkaline soils without negatively affecting the yield of sugar beet, soybean, corn, field bean, and wheat. Nutritional status of these crops should be carefully monitored after lime application.

The Effect of Detopping the Field Bean Plants (Vicia faba L. minor) and Lack of the Pod Setting on the Symbiosis with Root Nodule Bacteria

AbstractThe plants of field bean var. Nadwiślaνski were detopped after about 1 month since the beginning of flowering and after that all flower buds were removed from some plants. The effect of a change in the trophic balance on the setting and subsequent growth of root nodules was studied.The removal of pods had the greater effect on the increase in the weight of the remaining organs than the detopping of plants. Detopping retarded the ageing of the plants and delayed the phase of the greatest reduction of the number of pods. The detopping of plants revealed their considerable compensative possibilities in terms of production of the pod weight and the potential of leaves for biomass production. The data obtained indicate that plant detopping may disturb the root–bacteria exchange of signals, necessary to initiate the nodule development, while the further growth of nodules depends, above all, on the amount of available photosynthates.A very high correlation between the dry weight of the whole plant to the dry weight of leaves ratio and the weight of nodules was observed. It proves the importance of the trophic balance of the plant for the root nodule weight production.

Mechanism of sugar retention by roots of intact maize and field bean plants

Mechanism of sugar retention by roots of intact maize and field bean plants

Role of Plasmalemma H+ ATPase in Sugar Retention by Roots of Intact Maize and Field Bean Plants

AbstractNet release and net uptake of sugars by roots of intact maize (Zea mays cv. Blizzard) and field bean (Vicia faba L. cv. Alfred) were studied at micromolar external sugar concentrations that are relevant to the rhizosphere. Besides various sugars not further characterized there was net release of glucose, fructose, sucrose, arabinose, ribose, and galactose. The net release of these sugars into the root medium (0.1 mM CaSO4) was stimulated by the protonophore CCCP (10 μM), the sulfhydryl reagent NEM (300 μM), the specific inhibitor of plasmalemma H+ ATPase vanadate (0.5 mM), and by the inhibitor of the glucose carrier phlorizin (2 mM). Net uptake of glucose, fructose, and arabinose from 10 μM external concentrations was inhibited by these substances. Stimulation of net release and inhibition of net uptake was most pronounced for glucose. Sucrose added to the root medium was hydrolyzed by invertase activity leading to glucose and fructose uptake by roots. It is concluded that the retention of sugars by plant roots is not only determined by plasmalemma permeability but is also controlled by the H+ electrochemical gradient established by ATPase activity (retrieval mechanism). The proton gradient drives a sugar/H+ cotransport system that is selective for glucose but may also transport other sugars, particularly in the absence of glucose.

Development of a predictive uptake model to rationalise selection of polyoxyethylene surfactant adjuvants for foliage‐applied agrochemicals

AbstractComposition‐concentration relationships between a series of C13/C14 polyoxyethylene primary alcohol (AE) surfactants and the foliar uptake enhancement of five model neutral organic compounds were examined in factorially designed experiments on wheat (Triticum aestivum L.) and field bean (Vicia faba L.) plants grown under controlled environment conditions. Model compounds were applied to leaves as c.0.2‐μl droplets of 0.5 g litre−1 solutions in aqueous acetone in the absence or presence of surfactants at 0.2, 1 and 5g litre−1. Uptake of the highly water‐soluble compound, methylglucose (log octanol‐water partition coefficient (P) = ‐ 3.0) was best enhanced by surfactants with high E (ethylene oxide) contents (AE15, AE20), whereas those of the lipophilic compounds, WL110547 (log P = 3.5) and permethrin (log P = 6.5), were increased more by surfactants of lower E contents, especially AE6. However, there was little difference between AE6, AE11, AE15 and AE20 in their ability to promote uptake of the two model compounds of intermediate polarity, phenylurea (log P = 0.8) and cyanazine (log P = 2.1). Absolute amounts of compound uptake were also influenced strongly by both surfactant concentration and plant species. Greatest amounts of uptake enhancement were often observed at high surfactant concentration (5 g litre−1) and on the waxy wheat leaves compared with the less waxy field bean leaves. The latter needed higher surfactant thresholds to produce significant improvements in uptake. Data from our experiments were used to construct a simple response surface model relating uptake enhancement to the E content of the surfactant added and to the physicochemical properties of the compound to be taken up. Qualitative predictions from this model might be useful in rationalising the design of agrochemical formulations.

Effects of growth regulators on reproductive abscission in faba bean (Vicia fabacv. Troy)

SummaryGrowth regulators were applied to faba bean (field bean) plants in order to study hormonal control of premature reproductive abscission. Combined data from pairs of racemes sited in a consistently yielding region of the main stem indicated effects of growth regulator treatments. Decapitation increased pod numbers, but the inhibitory influence of the upper shoot could not be replaced completely by indol-3yl-acetic acid (IAA) applied to the cut stem stump. Blockage of auxin transport through the stem with the auxin-transport inhibitors 2, 3, 5-triiodobenzoic acid (TIBA) or methyl-2-chloro-9-hydroxyfluorene-9-carboxylate (CF, chlorflurenol) reduced pod numbers above the application point. The latter effects might have been indirect and due to elevated ethylene levels, since pod retention in this shoot region was decreased when sprayed with the ethylene-releasing compound 1-aminocyclopropane carboxylic acid (ACC) and increased when sprayed with ethylene-biosynthesis inhibitors 2-aminoethoxyvinyl glycine (AVG) or l-amino-2-cyclopropylcyclopropane carboxylic acid (cyclopropyl-ACC). Pod numbers were increased when the reproductive structures themselves were sprayed with IAA, gibberellic acid (GA3) or 6-benzylaminopurine (BAP), although a corresponding increase in total seed weight occurred only with the latter growth regulator. Application of BAP or abscisic acid (ABA) as root drenches showed that levels of reproductive abscission were raised or lowered with BAP treatment, depending on its concentration, and lowered with ABA treatment. It is suggested that growth regulator treatments leading to decreased ethylene production in the shoot and/or increased cytokinin and abscisic levels in the xylem sap are those most likely to reduce abscission.

Antagonistic effects of simultaneous exposure to sulphur dioxide gas and vapour of the herbicide 2, 4‐D iso‐octyl on the carbon dioxide exchange of tomato and field bean plants

summaryTomato and field bean plants were exposed simultaneously to SO2 gas (in the range 0.07–0.57 μg 1−1) and to vapour of the herbicide [14C]2, 4‐D iso‐octyl (0.8–2.7 ng 1−1), for periods of 6–24 h in an air‐flow system at a water vapour pressure deficit of &gt;2 kPa. Greater response was shown by the plants to 2, 4‐D vapour than to SO2. Herbicide vapour alone decreased CO2 exchange during the 3 d experimental period in both species, but the combination of herbicide plus SO2 had less effect. The response by tomato was both greater and more rapid than by field bean (which showed an initial stimulation of CO2 exchange due to 2, 4‐D), and the two species differed in the effect on transpiration. SO2 did not affect the uptake and distribution of herbicide within the plants. It appeared that 2, 4‐D iso‐octyl vapour and SO2 were antagonistic in effect on the CO2 exchange of the two species under the experimental conditions, and that in tomato this was largely due to changes in stomatal conductance.

Some physicochemical factors influencing foliar uptake enhancement of glyphosatemono(isopropylammonium) by polyoxyethylene surfactants

AbstractStructure‐concentration–foliar uptake enhancement relationships between commercial polyoxyethylene primary aliphatic alcohol (A), nonylphenol (NP), primary aliphatic amine (AM) surfactants and the herbicide glyphosatemono(isopropylammonium) were studied in experiments with wheat (Triticum aestivum L.) and field bean (Vicia faba L.) plants growing under controlled‐environment conditions. Candidate surfactants had mean molar ethylene oxide (EO) contents ranging from 5 to 20 and were added at concentrations varying from 0·2 to 10 g litre−‐1 to [14C]glyphosate formulations in acetone–water. Rates and total amounts of herbicide uptake from c. 0·2–μl droplet applications of formulations to leaves were influenced by surfactant EO content, surfactant hydrophobe composition, surfactant concentration, glyphosate concentration and plant species, in a complex manner. Surfactant effects were most pronounced at 0·5 g acid equivalent (a.e.) glyphosate litre−‐1 where, for both target species, surfactants of high EO content (15–20) were most effective at enhancing herbicide uptake: surfactants of lower EO content (5–10) frequently reduced, or failed to improve, glyphosate absorption. Whereas, at optimal EO content, AM surfactants caused greatest uptake enhancement on wheat, A surfactants gave the best overall performance on field bean; NP surfactants were generally the least efficient class of adjuvants on both species. Threshold concentrations of surfactants needed to increase glyphosate uptake were much higher in field bean than wheat (c. 2 g litre−‐1 and &lt; 1 g litre−‐1, respectively); less herbicide was taken up by both species at high AM surfactant concentrations. At 5 and 10 g a.e. glyphosate litre−‐1, there were substantial increases in herbicide absorption and surfactant addition could cause effects on uptake that were different from those observed at lower herbicide doses. In particular, the influence of EO content on glyphosate uptake was now much less marked in both species, especially with AM surfactants. The fundamental importance of glyphosate concentration for its uptake was further emphasised by experiments using formulations with constant a.i./surfactant weight ratios. Any increased foliar penetration resulting from inclusion of surfactants in 0·5 g litre−‐1 [14C]glyphosate formulations gave concomitant increases in the amounts of radiolabel that were translocated away from the site of application. At these low herbicide doses, translocation of absorbed [14C]glyphosate in wheat was c. twice that in field bean; surfactant addition to the formulation did not increase the proportion transported in wheat but substantially enhanced it in field bean.

Effects of inflorescence removal on interactions between reproductive storage sites of field beans (Vicia faba) under different shading treatments

SUMMARYIn studies of two indeterminate cultivars in field experiments in 1985 and 1986 at Hohenheim University, the hierarchy within the reproductive storage system of field bean plants was manipulated by removal of inflorescences at various growth stages and nodes. Shading reduced pod set and seed weight mainly at basal nodes. Increasing plant population density reduced seed yield traits at all nodes. Removal of basal inflorescences increased pod set and seed weight at the remaining nodes, especially the lower ones. The favourable effects were greater under high light intensities and in sparse stands. The growth stages at which the basal inflorescences were removed and the removal of apical inflorescences were of minor importance.

Effects of inflorescence removal on seed yield performance of field beans (Vicia faba) under different shading treatments

SUMMARYEffects of inflorescence removal under different plant densities and degrees of shading on seed yield of field beans (Vicia fabaL.) were investigated. Two indeterminate cultivars were used in field experiments for two seasons (1985 and 1986). The hierarchy within the generative storage system of field bean plants was manipulated by removal of inflorescences at various growth stages and nodes.Removal of the inflorescences of nodes 1–3 (counted from the base upwards) caused about 30% loss of seed yield potential compared with the control but compensatory increases in seed yield were found, differing with plant density and duration of shading. Under favourable growing conditions (no shading, 20 plants/m2), overcompensation occurred, giving a mean seed yield up to 40% more than in controls.Removal of all inflorescences above the ninth flowering node did not significantly reduce seed yield as plants completely compensated for the restriction on yield imposed.

Effects of Bean Leaf Age on Pathogenicity by Botrytis fabae

AbstractLeaves from field bean plants grown out of doors were inoculated with conidia of B. fabae immediately after detaching from stems. The oldest leaves developed more lesions than youngest ones, although they were not chlorotic. On intact plants at high humidities, established lesions on young leaves increased in size at only half the rate of those on old. but still green leaves. Seven days after inoculation a higher proportion of lesions on old leaves bore conidia than those on young leaves, but leaf age had no significant effect on numbers of conidia per mm2 of lesion area.Young leaflets from bean plants grown in a controlled environment or in the field challenged with β. cinerea accumulated more phytoalexins than did old ones.