Germination of sclerotia of Botrytis tulipae, the cause of tulip fire

Sclerotia of Botrytis tulipae (Lib) Lind. buried in field soil germinated mainly in winter and early spring to produce conidiophores and conidia and then decayed. Except when buried very late in the year sclerotia germinated and decayed in the season following burial. In the laboratory, sclerotia from pure culture germinated in two ways. On sterile water-agar they formed colourless mycelium but no conidiophores; the rate of germination was greatest at 25 d?C. On unsterile filter paper and on soil they produced mainly conidiophores and conidia; the rate of germination was greatest at 5 d?C and was enhanced by previous cold treatment. It was unaffected by soil-moisture or pH. Primary infections of tulips arose from sclerotia placed in the soil but only when they were close to the shoot tip or developing stem. It is suggested that, because of their limited survival, soil-borne sclerotia are of importance only when tulips are planted in annual succession.     

The effect of iprodione on the seed-borne phase of Alternaria brassicicola

Alternaria brassicicola infection of Brassica oleracea seeds was effectively controlled by a dust application of iprodione (Rovral 50% w.P.). At 2.5 g a.i./kg the seed-borne fungus was usually eliminated from samples with up to 61.5% affected seeds (35.5% internally diseased) but higher levels of infection required increased doses for complete eradication of the fungus. The germination of healthy seeds, including samples from 7–yr-old stocks, on filter paper was unaffected by the treatment. However, the germination of diseased samples, particularly those internally infected with A. brassicicola, was improved. More seedlings emerged from iprodione treated than from untreated seeds in glasshouse soil but the differences were not significant. The application of gamma-hexachlorocyclohexane to iprodione treated seeds sown in soil did not adversely affect subsequent emergence or disease control. Disease control was maintained and germination was not affected by the treatment when treated infected seeds were stored for 2 yr at 10 °C, 50% r.h. In a field trial iprodione seed treatment reduced seedling infection in a cabbage crop grown from naturally diseased seeds (100% contaminated, 45.5% internally infected) from 5.6 to 0.04%.     

Water-assisted dissemination of conidia of the mycoparasite Coniothyrium minitans in soil

A study was conducted to determine water-assisted dissemination of conidia of Coniothyrium minitans (Cm), a mycoparasite of Sclerotinia sclerotiorum (Ss), in four soils (yellow–brown soil, red-clay soil, fluvo-aquic soil and black soil) and one sand. Conidial suspensions (1×10⁷ conidia mL^?1) of Cm were applied to sieved (2 mm screen) soil or sand in glass tubes to test vertical dissemination (VD) and in aluminum boxes to test horizontal dissemination (HD) of conidia. Results showed that conidia of Cm could be disseminated with water and spread in soil or sand for 16–20 cm vertically and for 5–10 cm horizontally. The conidial concentration of Cm was logarithmically reduced with the increase in depth of VD or the distance of HD. Dissemination of Cm conidia in sand was better than that in four soils. Potting experiments were done to further understand the potential of water-assisted dissemination of Cm conidia in suppression of Ss carpogenic germination. Results showed that more apothecia were produced by Ss sclerotia located at the soil surface than those at 5 and 10 cm in depth. The minimum Cm concentration for suppression of Ss carpogenic germination was 1000 conidia g^?1 soil. Two-season field trials indicated that water-assisted application of Cm was an effective strategy used at the time for transplanting oilseed rape seedlings to suppress Ss carpogenic germination, thereby reducing the primary infection source for sclerotinia diseases of oilseed rape.     

Soil temperature and depth of legume germination during early and late dry season fires in a tropical eucalypt savanna of north‐eastern Australia

Abstract Temperatures that significantly increase seed germination of some tropical legumes (i.e. 80–100°C) were documented in the topsoil during the passage of early (May) and late (October) dry season fires in a tropical eucalypt savanna of north‐eastern Australia. Elevated temperatures penetrated at least 30 mm into the soil during the higher‐intensity, late dry season fires, but were only detected at 10 mm during the early dry season fires. The depth from which germination of two native legume forbs Galactia tenuiflora and Indigofera hirsuta occurred was positively related to the temperature elevation in the topsoil and was greater after late compared with early dry season fires. A broader range in germination depth, resulting in higher seedling densities, was recorded for I hirsuta after late dry season fires. These results suggest that seedling emergence of native leguminous forbs is likely to occur at a greater density after late rather than early dry season fires in tropical eucalypt savannas of north‐eastern Australia. Therefore, the season of burning, as a result of its relationship to fire intensity, can influence species composition through its effect on seed germination.     

GERMINATION ECOPHYSIOLOGY OF ARENARIA GLABRA,A WINTER ANNUAL OF SANDSTONE AND GRANITE OUTCROPS OF SOUTHEASTERN UNITED STATES

The germination ecophysiology of Arenaria glabra Michx., a characteristic winter annual plant species of granite and sandstone outcrops of southeastern United States, was investigated. Seeds germinate in early autumn, plants overwinter in the rosette stage and then flower, set seeds, and die in late spring; seeds are dispersed soon after maturity. Eighty-five to 90% of freshly-matured seeds were innately dormant, and the other 10–15% germinated only at temperatures lower than those that occur in the habitat at the time of seed dispersal in June. During the summer after-ripening period, seeds stored dry under ambient laboratory conditions exhibited progressive increases in rates and total percentages of germination, a widening of the temperature range for germination, and a loss of the light requirement. At a 14-hr daily photoperiod, seeds kept on continuously moist soil germinated to 83% at simulated July and August temperatures during July and August, and the remainder germinated at September temperatures in September. On the other hand, seeds subjected to alternate wetting and drying during July and August germinated to only 9% during those 2 months, and the remainder germinated after the soil was kept continuously moist, beginning on 1 September, at simulated habitat temperatures during September and October. Thus, the timing of germination of A. glabra in the field is controlled by an interplay of the seeds' physiological state with the dynamics of temperature and soil moisture conditions.     

Effects of biological soil crusts on seed germination of four endangered herbs in a xeric Florida shrubland during drought

Soil crusts of rosemary scrubs in south-central Florida were examined for effects on seed germination of four herbs that are killed by fire and must recruit from seed: Eryngium cuneifolium (Apiaceae), Hypericum cumulicola (Hypericaceae), Polygonella basiramia (Polygonaceae), and Paronychia chartacea ssp. chartacea (Caryophyllaceae). Biological soil crusts in these sites are dominated by algae, cyanobacteria, fungi, and bacteria. Because crusts can change soil stability, water, and nutrients, they can affect seed germination. A series of greenhouse and field experiments were designed to first examine the effects of crusts in isolation and then to determine their role in the context of other environmental factors – time since fire and distance to the dominant shrub in this system, Ceratiola ericoides. In the greenhouse experiment, germination in autoclaved crusts was dramatically reduced relative to germination in living crusts for all but P. basiramia. In four field experiments where crusts were left intact, disturbed (mechanically or by flaming), or completely removed, the effects of crusts were variable and species-specific, but were significant enough to impact aboveground population sizes. More germination was consistently observed in recently burned sites away from C. ericoides shrubs. Overall rates of germination were generally very low during this study, possibly as a result of seasonal droughts that could have reduced germination, increased seed dormancy, and/or decreased seed viability. The importance of water for germination was confirmed in an experiment with two watering regimes and three crust treatments designed to create a gradient of soil water availability. Germination was significantly greater in the high water treatment and unaffected by soil crust moisture. Dry years are not uncommon in scrub and the results of this study help us to understand how scrub herbs fare during drought and what role biological soil crusts play in germination.     

Prediction of cotton seedling germination against pre-emergence damping off on the basis of environmental factors and seed applied fungicides

Cotton is an important fibre crop chiefly attacked by a number of diseases. Pre-emergence damping off seedling is an important disease of cotton. Efficacy of three fungicides (Dynesty, Topsin-M and Antracol) was assessed on early mid and late sowings. Topsin-M and Antracol were evaluated at 1X and 2X concentrations, Dynasty was only used at standard dose. Significant increase in seed germination was seen, maximum germination was observed in late sowing. Antracol (2X) significantly improved seed germination rate in all three sowings as compared to other treatments. Impact of environmental parameters on germination rate was assessed relating to seed dressing fungicides at 1X and 2X concentrations. Significant correlation was observed between soil temperature and seedling germination rate by all treatments, 30–31 °C favoured germination rate. Maximum seedling germination rate was observed at 24–26 and 22–23 °C and 45–50% by average air temperature, minimum air temperature and relative humidity respectively. Regression model was contrived to predict seedling germinations impacted by seed dressing fungicides relating to environmental factors. Closed resemblance between observed and predicted values states that model can be used to predict seed germination by treating with fungicides regarding to environmental factors.     

Environmental factors affecting seed germination of gray birch (Betula populifolia) collected from abandoned anthracite coal mine spoils in northeast Pennsylvania

Germination of gray birch (Betula populifolia) seed collected from anthracite mine spoils in northeastern Pennsylvania was studied. Environmental conditions of the spoil banks are such that high mortality may occur at seed and germination stages because of low moisture availability and thermal stress. The mine spoil banks are harsh environments with respect to key seed germination factors: percent soil moisture as low as 1.8% and soil surface temperatures reaching 59°C. In the field, gray birch typically germinated in mid-April prior to severe environmental stress. Trends in germination success were inversely related to rising soil temperature and decreasing soil moisture availability. Although seeds were capable of survival and germination under laboratory conditions of constant temperatures in excess of 55°C, dramatic decline in germination was observed under fluctuating temperature regimes likely to be experienced in the field. No germinations occurred under fluctuating temperatures in excess of 30°C. Germinations in the field were seen to end after mid-June when substrate temperatures exceeded 30°C.     

Effects of Biological Soil Crusts on Seed Bank, Germination and Establishment of Two Annual Plant Species in the Tengger Desert (N China)

The presence of biological soil crusts can affect the germination and survival of vascular plants, but the reasons are not well investigated. We have conducted a field investigation and greenhouse experiments to test the effect of crusts on two desert annual plants, which occur on the stabilized dunes of the Tengger Desert in N China. The results showed that biological soil crusts negatively influenced the seed bank of Eragrostis poaeoides and Bassia dasyphylla. The important effect of biological soil crusts on seed germination and establishment were performed indirectly through reducing the amount of germinating seeds. Field investigation and experimental results with regard to the seed bank indicated that higher seedling density was found in disturbed crust soil and bare soil surface than in intact crust soils. Greenhouse experiments showed that the effects of biological soil crusts on germination and establishment of the two plants are not obvious in moist condition, while disturbed crusts are more favorable to seed germination in dry treatment. Significant differences in biomass were found between disturbed crust soil and bare soil. Survival and growth of the two annual plants were enhanced in both algal and moss crusts during the season of rainfall or in moist environment, but crusts did not affect seedling survival in the dry period. The small seeded E. poaeoides has higher germination than larger-seeded B. dasyphylla in crust soils, but B. dasyphylla has a relatively higher survival rate than E. poaeoides in crust soils.     

Field fate of Amaranthus patulus seeds subjected to leaf-canopy inhibition of germination

Summary The germination of seeds of Amaranthus patulus Bertol., is known to be sensitive to leaf-transmitted light. Seeds were enclosed in transparent polyester-mesh envelopes and placed horizontally in 10-cm deep soil or on the soil surface, beneath a closed vegetation cover in the field. Changes in the numbers of firm intact seeds and of germinable seeds were traced for up to 3 years by periodical retrievals and germination tests. Rapid loss of germinable seeds, mainly due to germination, was observed in the buried seed population, in which only 20% of seeds maintained their germinability after 1 year, and a negligible number after 3 years. In contrast, the seeds placed on the soil surface maintained germinability relatively well: over 80% of seeds remained germinable after 1 year and a low percentage still preserved their germinability after 3 years. Assuming exponential decay in germinability, the decay rates on and in the soil were calculated from the data of the 1-year experiment to be 0.21 and 0.84 year^-1 respectively. The fate of seeds that were exposed to canopy light on the soil for a month and then buried was shown to be almost the same as that of the seeds which had been continuously in 10-cm deep soil. Correspondingly, the possibility of the induction of secondary (induced) dormancy by exposure to canopy light was excluded in a laboratory experiment, in which it was found that the imbibed seeds suffering leaf-canopy inhibition of germination exuded some diffusible germination inhibitor responsible for apparent dormancy. Estimation of numbers of A. patulus in the seed bank of an early successional field showed that 3,500 seeds/m² remained in the soil to the depth of 10 cm after 3 years' exclusion of the species following the production of 700,000 seeds/m², by a population explosively established after experimental induction of secondary succession.     

Germination ecology and seed population dynamics of Digitalis purpurea

Summary The germination ecology and the dynamics of the generative reproduction in populations of Digitalis purpurea L. were investigated in the field as well as in experiments. Germination of fresh seeds in the dark on moist filter paper appeared to differ between populations. These differences were eliminated when a moist natural soil functioned as germination substrate. An interaction between the spectral composition of light and the germination substrate was present. Germination in gradients of light, temperature and soil moisture revealed some clear-cut results. Germination proved to be strongly dependent on the percentage of vegetation cover. During two years of burial in litter bags, the number of buried viable seeds did not decrease. From one generation of seeds produced in a natural population, 18% was introduced into the buried seed bank, 10% germinated in autumn and 24% was present as a enforced dormant surface seed bank in late autumn.The results are discussed in relation to secondary succession. can be derived from Milton (1936), Salisbury (1942) and Thompson and Grime (1979). Soil disturbance and germination seem to be correlated in D. purpurea (Grime 1979). The purpose of this study is to analyse the dormancy and germination behaviour of D. purpurea in relation to the relevant environmental factors in order to explain the mechanisms of entry into, and the escape of D. purpurea seeds from a seed bank. Furthermore, an attempt will be made to quantify seed rain as well as the fate of different germinating and non-germinating seed rain fractions in space and time per unit area, in different stages of succession.     

Mechanisms regulating seedling emergence of orchardgrass (Dactylis glomerata L.) and western wheatgrass (Pascopyrum smithii [Rydb.] L.): Dormancy change,seed fate and seeding date

Seed germination and seedling emergence of ‘Arctic’ and ‘Lineta’ orchardgrass (Dactylis glomerata L.) and ‘Walsh’ and ‘LC9078a’ western wheatgrass (Pascopyrum smithii [Rydb.] L.) were studied both in the field and laboratory. Four seeding dates were conducted each year over 2 years and seedling emergence and seed fate in the soil were monitored. The effects of alternating temperature and light on germination were quantified and correlated with seedling emergence from soil and in the field. Orchardgrass seeds were less dormant than western wheatgrass as indicated by the disparity in germination percentage between constant and alternating temperatures. Seed germination percentage was usually higher than seedling emergence in the field for orchardgrass but lower for western wheatgrass, and temperature was not responsible for the difference. Exposing orchardgrass seeds to light during germination check helped break dormancy in orchardgrass when temperature was unfavorable (low and/or constant temperatures), while favorable temperatures (optimal, alternating temperatures) conditions overcame the inhibiting effect of light in western wheatgrass. The final seedling emergence of orchardgrass was either similar among the four seeding dates or decreased slightly from early May to early June. For western wheatgrass, however, final seedling emergence increased with seeding dates from early to late May and decreased in early June. Soil temperatures of the first 2 weeks after seeding increased from the early May to late May and then decreased. These temperatures were below or near the optimal temperatures for western wheatgrass seeds to release dormancy and germinate. Germination of the previously buried seeds indicated that orchardgrass and western wheatgrass had the potential for a high germination percentage under field conditions for all seeding dates. While soil temperatures close to the optimal temperature for dormancy breaking and germination promoted germination of orchardgrass, the same conditions could cause deterioration of seeds if they failed to germinate. For western wheatgrass, deeper dormancy reduced seed mortality.     

Organic matter inputs create variable resource patches on Puerto Rican landslides

Landslides are a frequent disturbance in montane tropical rainforests that result in heterogeneous environments for plant and soil development. Natural inputs of organic matter and associated nutrients contribute to soil fertility patchiness within landslides. To test the importance of organic matter and nutrient addition to landslide soil fertility and plant growth, we mixed three types of organic matter substrates that are common to landslides (Cecropia leaves, Cyathea fronds, and forest soil) and commercial fertilizer into recently eroded soil on five landslides in Puerto Rico. In addition, we sowed seeds of two common landslide colonists (Paspalum and Phytolacca) into the soil treatment plots in order to test treatment effects on seed germination and seedling growth. Soils, seed germination, and seedling growth were monitored for one year and the field experiment was replicated in a one-year screen-house experiment. Despite highly variable initial landslide conditions, responses to soil treatments were similar across all five landslides. The forest soil addition increased total soil nitrogen and soil organic matter on landslides within 60 days, whereas Cecropia leaves provided increased soil organic matter only after 210 days. Commercial fertilizer increased plant-available soil nitrogen and phosphorus within 60 days, and also increased seed germination of Paspalum seeds when compared to soils treated with Cecropia leaves. Despite these positive effects of treatments on soils and germination, there were no treatment effects on seedling growth in the field, perhaps due to leaching or other losses of soil nutrients evident in the lack of significant treatment differences in soil resources at 370 days. In the screen-house, forest soil and commercial fertilizer treatments significantly increased soil fertility and seedling growth of both Paspalum and Phytolacca compared to control treatments. These different responses to three common types of organic matter inputs create patchy soil conditions with important implications for plant colonization and landslide succession.     

The role of the sexual stage in the over-summering of Erysiphe graminis DC. f.sp. hordei Marchal under semi-arid conditions

The sexual stage of E. graminis f.sp. hordei was found to be functional in Israel, and adapted to the climate of the region. Cleistothecia serve as the principal, and perhaps the only means for persistence of the pathogen in the host-less, hot and rainless summer, and induce initial infection on wild and cultivated barleys in late autumn. The cool and rainy weather, which induces germination of seeds of the host in the field, also permits ascospore differentiation and ejection. Details are given of the conditions favouring or delaying cleistothccial maturation during and after the growing season.     

Sclerotia of Botrytis as a Source of Primary Inoculum for Bunch Rot of Grapes in New South Wales, Australia

Sclerotia of Botrytis cinerea were found to be a source of primary inoculum for bunch rot of grapes in the Hunter Valley of New South Wales. Conidia-bearing sclerotia were found on canes on grapevines. Resporulation of sclerotia was observed and sporogenic germination led to infection of flowers and berries. Sclerotia survived for eight months in untreated soil in the laboratory. Application of dicarboximides (procymidone, iprodione and vinclozolin) reduced infection of flowers and bunch rotcaused by the sporogenic germination of sclerotia.     

GERMINATION ECOLOGY OF PHACELIA DUBIA VAR. DUBIA IN TENNESSEE GLADES

The germination characteristics of a population of the winter annual Phacelia dubia (L.) Trel. var. dubia from the middle Tennessee cedar glades were investigated in an attempt to define the factor(s) regulating germination in nature. Factors considered were changes in physiological response of the seeds (after-ripening), temperature, age, light and darkness, and soil moisture. At seed dispersal (late May to early June), approximately 50 % of the seeds were non-dormant but, would germinate only at low temperatures (10–15 C). As the seeds aged from June to September, there was an increase in rate and total percent of germination at 10, 15, and 20 C, and the maximum temperature for germination increased to 25 C. Little or no germination occurred at the June, July, and August temperatures in 0- to 2-month-old seeds, even in seeds on soil that was kept continuously moist during this 3-month period. At the September, October, and November temperatures 3- to 5-month-old seeds germinated to high percentages. In all experiments seeds germinated better at a 14-hr photoperiod than in constant darkness. Inability of 0- to 2-month-old seeds to germinate at high summer temperatures allows P. dubia dubia to pass the dry summer in the seed stage, while increase in optimum and maximum temperatures for germination during the summer permits seeds to germinate in late summer and early fall when conditions are favorable for seedling survival and eventual maturation.     

Effects of fungicides on the growth and conidial germination of Colletotrichum coccodes and on the development of black dot disease of potatoes

The effects of 10 fungicides on the growth of Colletotrichum coccodes in agar culture and on the germination of conidia was investigated. In field experiments in 1990 and 1991 the extent to which treating black dot-affected potato seed tubers with fungicides affected the development of the disease on stem bases, roots and tubers was assessed. Black dot was also assessed on plants from field trials in 1990 which were designed to investigate the efficacy of the soil sterilant 1,3-dichloropropene (Telone) and two nematicides, aldicarb (Temik) and ethoprophos (Mocap). Prochloraz and fenpiclonil were the most effective fungicides in decreasing the size of C. coccodes colonies on agar. Imazalil, propiconazole and dichlorophen were also effective, but at higher concentrations, whereas tolclofos-methyl, thiabendazole and benomyl were only moderately effective. Resistant sectors developed from inhibited colonies on agar containing fenpiclonil and tolclofos-methyl. Conidial germination was prevented at 1 mg/litre fenpiclonil and 5 mg/ litre dichlorophen; imazalil, benomyl and thiabendazole were also moderately effective. Fenpiclonil and propiconazole seed tuber treatments consistently decreased black dot infection on roots, stem bases and daughter tubers early in the season, but only fenpiclonil decreased disease on tubers at harvest in October. Propiconazole also delayed emergence and decreased stem numbers. Soil treatment with 1,3-dichloropropene, aldicarb or ethoprophos had no effect on black dot but Rhizoctonia solani tuber infection and black scurf were increased.     

Additional experiences to elucidate the microbial component of soil suppressiveness towards strawberry black root rot complex

Several studies were carried out to investigate the soil microbial components involved in suppressing strawberry black rot root which occurs throughout the Italian strawberry growing region. Quantitative and qualitative evaluation of fungi involved in black root rot were combined with several soil microbial parameters involved in soil suppressiveness towards black root rot agents. The first survey, carried out in an intensively cultivated area of northern Italy, identified Rhizoctonia spp. as the main root pathogen together with several typical weak pathogens belonging to the well‐known black rot root complex of strawberry crop: Cylindrocarpondestructans, Fusarium oxysporum, F. solani, Pestalotia longiseta and others. The root colonisation frequency of strawberry plants increased strongly from autumn to spring at harvesting stage. Rhizoctonia spp. were the only pathogens which followed the rising trend of root colonisation with relative frequency; all the weak pathogens of strawberry black root rot complex did not vary their frequency. Only non‐pathogenic fungi decreased from autumn to spring when at least 60% of colonising fungi were represented by Rhizoctonia. These data suggested that the late vegetative stage was the best time to record the soil inoculum of root rot agents in strawberry using root infection frequency as a parameter of soil health. A further study was performed in two fields, chosen for their common soil texture and pH, but with significant differences in previous soil management: one (ALSIA) had been subjected to strawberry monoculture without organic input for several years; the other (CIF) has been managed according to a 4‐year crop rotation and high organic input. In this study Pythium artificially inoculated was adopted as an indicator for the behaviour of saprophytically living pathogens in bulk soil. Pythium showed a sharp, different response after inoculation in bulk soil from the two soil systems evaluated. Pythium was suppressed only in the CIF field where the highest levels of total fungi and fluorescent bacteria and highest variability were observed. The suppressiveness conditions towards Pythium, observed in the CIF and absent in the ALSIA field, corresponded with the root infection frequency recorded at the late vegetative stage on strawberry plants grown in the two fields: strawberry plants from the CIF field showed lower root colonisation frequency and higher variability than that recorded on those coming from the ALSIA field.     

Seed ecology of dust seeds in situ: a new study technique and its application in terrestrial orchids

A method is described by which seeds of terrestrial orchids are sown and retrieved in the field under almost natural conditions. For the first time it is possible to conduct a quantitative study of orchid germination in situ and observe seasonal growth and mortality of seedlings. The technique has also enabled us to investigate the relation between the site where the seeds are sown, the availability of an appropriate fungus to infect the seeds, and seedling establishment in the soil. Five local species were studied. Corallorhiza odontorhiza, Goodyera pubescens, and Galearis spectabilis all began to germinate in May–June, after 23-30 weeks in the soil. These species differed in their dependency on infection at germination time, but none of the seedlings developed beyond the point of rupturing the testa except when infected. Seeds of Liparis lilifolia and Tipularia discolor did not germinate within the first 12 months of the experiment. The implications and potential uses of this field sowing technique for further studies and for other kinds of minute seeds are discussed.     

The ecology of ectomycorrhiza formation and functioning

Factors in inoculum potential/infection levels/plant growth response are analysed and experimental approaches to propagule germination, growth through soil and rhizosphere growth are indicated. It is suggested that seedling rhizosphere germination of basidiospores occurs particularly with early stage fungi, while late stage fungi may be advantaged by germination/growth on exudates from older parts of roots or on litter (and its associated microorganisms) and their tolerance of antimicrobial substances in litter. Relative growth in the rhizosphere is likely to dominate the mycorrhizal species composition and this may be a good selection method for organisms tolerant of stress and pollution conditions. As mycorrhizal function in nutrient uptake is largely determined by fungus growth into soil, there is need for much more experimental study of factors affecting this, and of the potential photosynthate drain this could represent. The possibility of selection/breeding mycorrhizal fungi with both ‘early stage’ and ‘late stage’ attributes is raised.