Manganous oxide as a seed-pellet additive for controlling manganese deficiency in sugar-beet seedlings

Summary Experiments in the laboratory, glasshouse and field during 1975–78 tested manganous oxide as a seed-pellet additive for controlling deficiency in sugar-beet seedlings. There was no experimental evidence that manganous oxide in the seed pellet was ever harmful to seedling establishment. On the contrary, germination tests in the laboratory and experiments in the glasshouse indicated that, in certain conditions, manganous oxide may improve plant establishment even when plants are not likely to be deficient, probably by accelerating germination of seed and emergence of seedlings. In field experiments where sugar beet were severely deficient, the plants were heavier and contained more manganese on plots sown with seed pelleted with material containing 50% manganous oxide than on plots sown with ordinary pelleted seed. Applying a foliar spray of manganese sulphate during the third week of June in addition to pelleting the seed with material containing manganous oxide gave bigger yields than either the seed-pellet treatment or foliar spraying alone.     

Manganese deficiency of sugar beet in organic soils

Summary The manganese content of sugar beet grown in pots of organic soils taken from fields where crops regularly show symptoms of manganese deficiency, and the effects on it of foliar sprays of manganous sulphate and of manganous oxide or manganese silicate frit applied to the soil, of changing the soil pH, air-drying the soil, and growing the plants either in the glasshouse or outside were determined. All the manganese treatments increased the concentration of manganese in the plants and decreased deficiency symptoms, but increased the dry matter yield only slightly. Increasing the pH by liming greatly increased symptoms and decreased the manganese concentration in the dry matter; air-drying the soil before cropping had the opposite effect. Plants grown in pots of the same soil in the glasshouse or outdoors showed similar symptoms and had similar manganese content.The concentration of manganese in the leaves was related to the percentage of plants with deficiency symptoms and to the concentration of active soil manganese. Leaves usually had symptoms when the concentration of manganese in the dried leaves was less than 30 ppm, and always had severe symptoms when they contained less than 15 ppm Mn. The soil analyses suggest that sugar beet grown in organic soil with pH greater than 7.0 and containing less than 40 ppm active soil manganese is likely to show deficiency symptoms.     

The effect of phosphate application on manganese content of plants grown on neutral and alkaline soils

Summary In four field experiments high rates of granular triple superphosphate and repeated sprays of manganese sulphate were applied to oats and sugar beet on land known to produce manganese-deficiency symptoms in these crops. It was found that spraying did not increase the manganese content of the foliage while application of superphosphate did.Possible explanations for this are discussed and it is suggested that the most likely one is chemical mobilization of soil manganese brought about by the reactions that the monocalcium phosphate in superphosphate undergoes in soil.     

Some causes of chlorosis and necrosis of sugar-beet foliage

The symptoms and characteristics of two virus and one fungus disease and four nutritional disorders of sugar beet which cause chlorosis and necrosis of the foliage are described. The causes of the diseases and methods of distinguishing between them have been investigated by analytical, pathological and field experimental methods.
Experiments in which diagnosis was confirmed by serological and spectrochemical methods show that the two often easily confused diseases, sugar-beet yellows virus and magnesium deficiency, can be visually distinguished.
Sugar-beet yellows virus reduces the potassium, but slightly increases the magnesium content of the leaves.
Magnesium deficiency symptoms are associated with a low magnesium content of the foliage, but may be induced by salt applications without greatly affecting the magnesium analysis.
'Potash' deficiency symptoms are often, but not necessarily, associated with a low potassium analysis and may actually be caused solely by a deficiency of sodium. In the field, symptoms are induced by sulphate of ammonia and phosphate applications and may be prevented in some cases by the application of either salt or muriate of potash, in others by salt only. Some interchangeability of the functions of potassium and sodium in the plant is suggested.
Manganese deficiency symptoms are associated with a low manganese content of the leaves, which can be readily increased by spraying or injection with manganese sulphate solution, but a high concentration of manganese in the foliage, such as sometimes occurs naturally on acid soils, has a toxic effect.     

On the effect of ferrous sulphate on the available manganese in the soil and the uptake of manganese by the plant

Summary Application of iron as ferrous sulphate or chloride to a loam not deficient in manganese had no effect on the yield but increased the uptake of manganese even in barley which grew vigorously.In an experiment with sugar beet on two soils contrasted with regard to their available manganese supply, applications of manganese, iron and nitrogen were tested in all combinations. On the Købelev soil, not deficient in manganese, no increases in yields were obtained on addition of ferrous sulphate while increases in manganese uptake were found for all combinations of treatments except where iron was added in the presence of manganese.On the manganese deficient Faarevejle soil, significantly higher increases in yields of roots were obtained from ferrous sulphate in the presence of nitrogen than in the presence of manganese. The effect of iron in the presence of nitrogen on the yield of tops was also significant. These treatments also gave the highest increases in manganese uptake.The amounts of manganese extractable from the soils by magnesium nitrate over a range of pH 2–8 could be increased considerably by addition of ferrous sulphate.The results support the suggestion that application of ferrous sulphate to some soils has the same effect as an addition of manganese.     

Effects of the pyrethroid deltamethrin on the acquisition and inoculation of viruses by Myzus persicae

The pyrethroid, deltamethrin, alone or as an emulsifiable formulation, hindered infection of healthy plants with the persistent beet mild yellowing virus (BMYV) and both acquisition of, and infection with, the non-persistent potato virus Y (PVY) and the semi-persistent sugar beet yellows virus (BYV) by Myzus persicae in glasshouse tests.
Another pyrethroid, RU-15525, also protected against infection with PVY. Even sub-lethal amounts of deltamethrin decreased virus transmission by rapidly incapacitating the aphids, the effect being least with aphids most resistant to organophosphorous insecticides and to certain pyrethroids including deltamethrin. Demeton-S-methyl hindered infection only with BMYV. This work shows that deltamethrin restricts transmission of persistent, semi-persistent and perhaps more importantly of non-persistent viruses in the glasshouse, and has potential for doing the same in the field.     

SUGAR BEET YELLOWS: A PRELIMINARY STUDY OF THE DISTRIBUTION AND INTERRELATIONSHIPS OF VIRUSES AND VIRUS STRAINS FOUND IN EAST ANGLIA, 1955-57

Aphid transmissions to sugar beet seedlings from yellowed sugar beet leaves collected from commercial fields in East Anglia during the summers of 1955, 1956 and 1957, showed the occurrence of two yellowing viruses. One was sugar beet yellows virus (SBYV) and produced vein-etch and yellowing symptoms on beet seedlings in the glasshouse; the other produced yellowing but no etch. These two viruses were apparently unrelated, so that sugar beet tolerant to one of them would not necessarily be tolerant to the other. The second virus, called 'sugar beet mild yellowing virus' (SBMYV), decreased the root yield of sugar beet plants grown under glass, by as much as did the milder SBYV strains, but less than did the severe SBYV strains. The proportions of the two viruses in the samples differed from year to year and from place to place.     

The availability of various manganese oxides to plants

Summary A number of oxides of manganese were prepared and their crystalline structures were indentified by X-rays. They were added to four soils on which plants suffered from manganese deficiency. Oxides of the structures manganite, manganous manganite, and pyrolusite cured manganese deficiency of oats and peas. All the successful oxides consisted of very small particles, as shown by electron micrographs.The amount of the oxides dissolved by aqueous quinol during an hour at room temperature was correlated with their ability to supply plants with manganese.     

The use of water and some inorganic salt solutions to advance sugar beet seed. II. Experiments under controlled and field conditions

The effect of seed advancement on the early growth of sugar beet was determined in two experiments made under controlled conditions and eight field experiments made between 1974 and 1978. The experiments in the growth room suggested that seed advancement increased the rate of emergence and seedling dry weight over a wide range of soil moisture contents but seedling numbers were only greater under sub-optimal moisture conditions. Similarly, in most field experiments, seed advancement resulted in more rapid emergence and larger seedlings. In four field experiments, seed advancement gave up to 16% more plants, and in three experiments a significant increase in final sugar yield of up to 0–7 t h^-1 was detected. The plants were hand-singled to a uniform stand and had the crops been drilled to a stand, some yield responses would have been larger. Seed advancement did not decrease the plant stand or final yield in any experiments. Results in 1977 and 1978 provided some evidence that seed advancement may help reduce the damage caused by field mice and the number of plants which bolt and, by making emergence more rapid, be particularly beneficial on soils prone to slumping or capping. There might, however, be a slightly increased risk of frost injury if advanced seed is used for early sowings.     

The influence of black bean aphid, Aphis fabae Scop., and its honeydew on leaf growth and dry matter production of sugar beet

A. fabae populations, started at the 3–4 leaf-stage of sugar beet in the glasshouse and peaking at 3000 individuals per plant, reduced leaf area by 64% at the 14 leaf-stage. The size of the heavily-infested leaves number 5 to 10 was reduced by 80% or more. The rate of leaf growth regained normal values after the aphid populations collapsed, but the infested plants did not make up for the decrease in leaf area production that had been incurred during the infestation. Total dry matter production over a period of 15 weeks was reduced by 47%. Honeydew had no effect on leaf size or dry matter production. Sugar beet plants in the field became infested with A. fabae at the 2–3, 4–5 and 6–8 leaf stages. Maximum populations of 800, 2100 and 2200 aphids per plant were recorded, respectively. The pertinent reductions in leaf area were 91%, 67% and 34% at the 10–12 leaf-stage and 79%, 65% and 14% at harvest while the total dry matter produced was reduced by 91%, 79% and 16%. Neighbouring plants of the early-infested sugar beet plants gained significantly higher weights than control plants. Honeydew had no effect on leaf area or dry matter production. The consequences of these results for our understanding of Aphis fabae injury in sugar beet and aphid control in the field are discussed.     

The influence of black bean aphid, Aphis fabae Scop., and its honeydew on the photosynthesis of sugar beet

The effect of black bean aphids on the photosynthesis of sugar beet plants was studied under glasshouse and field conditions. The presence of up to several hundred aphids per leaf had no significant effect on CO₂ exchange rates over a range of light intensities between complete darkness and light saturation. Artificially prepared honeydew, sprayed onto leaves in the same amounts and composition as was found on severely aphid-infested plants, covered 30% of the stomata on the upper epidermis but did not significantly alter the rate of photosynthesis of these leaves in the light or the rate of respiration in the dark. The stomata on the lower epidermis were uncovered and functional. High pressure liquid chromatography of aphid-produced honeydew detected 20 different amino-acids. Three amino-acids, aspartic acid, glutamic acid and gluta-mine, made up the bulk of the amino-acid weight in the honeydew produced on young plants, up till the 8 leaf-stage. In the 10 to 12 leaf-stage, several different amino-acids occurred in substantial amounts. The amino-acids to sugars ratio of the honeydew produced by the aphids decreased strongly as the sugar beet plants aged: from 1:6 in plants with 3 or 4 leaves to 1:25 in plants having 10 to 12 leaves.     

Analysis of gene inheritance and expression in hybrids between transgenic sugar beet and wild beets

Reciprocal gene exchange between cultivated sugar beet and wild beets in seed production areas is probably the reason for the occurence of weed beets in sugar beet production fields. Therefore, when releasing transgenic sugar beet plants into the environment, gene transfer to wild beets ( Beta vulgaris ssp. maritima ) has to be considered. In this study the transfer of BNYVV- (beet necrotic yellow vein virus) resistance and herbicide-tolerance genes from two transgenic sugar beet lines that were released in field experiments in 1993 and 1994 in Germany to different wild beet accessions was investigated. In order to evaluate the consequences of outcrossing, manual pollinations of emasculated wild beet plants with homozygous transgenic sugar beet plants were performed. In the resulting hybrids the transgenes were stably inherited according to Mendelian law. Gene expression in leaves and roots of the hybrids was in the same range as in the original transgenic sugar beet plants. Moreover, it was found that in one of the wild beet accessions, transfer and expression of the BNYVV resistance gene did considerably increase the level of virus resistance.     

SUGAR-BEET YELLOWS: FURTHER STUDIES ON VIRUSES AND VIRUS STRAINS AND THEIR DISTRIBUTION IN EAST ANGLIA, 1958-59

Experiments have shown that, as in the years 1955-57, two yellowing viruses, beet yellows virus (SBYV) and sugar-beet mild yellowing virus (SBMYV), were present in commercial sugar-beet crops in East Anglia in 1958 and 1959. The evidence that they are not closely related viruses has been confirmed. In both years the prevalence of the two viruses was estimated by aphid transmissions from yellowed sugar-beet leaves to healthy sugar beet and Chenopodium capitatum seedlings in the glasshouse, and in 1959 additionally by examination of symptoms on field plants. SBMYV was more common than SBYV over the whole region in 1958, but in 1959 SBYV was slightly more prevalent than SBMYV. In both years SBYV was found more often in the southern than in the northern parts of the region. The results described in this paper suggest that breeding for tolerance to SBMYV may be at least as important economically in East Anglia as breeding for tolerance to SBYV. A wide range of SBYV strains was present in East Anglia in 1959, most of the strains being those which caused severe symptoms in sugar beet and C. capitatum.     

A comparison of manganese sources using tomato plants grown on marl,peat and sand soils

Summary The availability of manganous oxide, manganese dioxide and MnEDTA was compared to that of manganous sulfate at several equivalent rates on a Mn-deficient peaty muck, marl and on Mn-sufficient Scranton sand. Tomato plants grown in pot studies were analyzed for manganese and iron. Mn-deficiency leaf symptoms were in general agreement with the manganese level in the plant and the Fe/Mn ratio. Iron intake and manganese intake showed some evidence of inverse relationships. Manganous sulfate was slightly more available than manganous oxide which, in turn, was more available than MnO₂ or MnEDTA.     

Effect of the polysaccharide ofAgrobacterium radiobacter on the growth of plants and occurrence of damping-off in sugar beet

Agrobacterium radiobacter, strain B6 (a strain isolated in this laboratory, which limited the occurrence of damping-off of sugar beet and influenced growth of plants in hot-house and field experiments) was found to produce an acidic exopolysaccharide in a mineral medium with various carbon sources. Hydrolyzates of the polysaccharide contained glucose, galactose, glycerol, succinic acid and pyruvic acid, whose quantitative content varied according to the carbon source used. The polysaccharide isolated from the medium containing glucose exhibited the highest physiological activity. Seeds germinated best and sugar beet roots were found to grow most rapidly in a medium containing 0.2 % (W/W) of the polysaccharide. The roots exposed for 3 d in this medium grew 2.7-fold as compared with non-treated plants. Higher sumbers of microorganisms were detected on the surface of roots treated with the polysaccharide. Growth of roots was also stimulated when immersing the seeds (30 min) in a 0.2 –0.4 % solution of this polysaccharide. After a two-fold treatment the roots were less damaged by the fungusPythium ultimum. Plants from seeds treated with the polysaccharide grew in the field soil more rapidly than the non-treated plants but worse than after bacterization of the seeds byA. radiobacter B6 and were only partially protected against the damping-off of sugar beet.     

Intra-plant variation in nectar sugar composition in two Aquilegia species (Ranunculaceae): contrasting patterns under field and glasshouse conditions

BACKGROUND AND AIMS: Intra-specific variation in nectar chemistry under natural conditions has been only rarely explored, yet it is an essential aspect of our understanding of how pollinator-mediated selection might act on nectar traits. This paper examines intra-specific variation in nectar sugar composition in field and glasshouse plants of the bumblebee-pollinated perennial herbs Aquilegia vulgaris subsp. vulgaris and Aquilegia pyrenaica subsp. cazorlensis (Ranunculaceae). The aims of the study are to assess the generality of extreme intra-plant variation in nectar sugar composition recently reported for other species in the field, and gaining insight on the possible mechanisms involved. METHODS: The proportions of glucose, fructose and sucrose in single-nectary nectar samples collected from field and glasshouse plants were determined using high performance liquid chromatography. A hierarchical variance partition was used to dissect total variance into components due to variation among plants, flowers within plants, and nectaries within flowers. KEY RESULTS: Nectar of the two species was mostly sucrose-dominated, but composition varied widely in the field, ranging from sucrose-only to fructose-dominated. Most intra-specific variance was due to differences among nectaries of the same flower, and flowers of the same plant. The high intra-plant variation in sugar composition exhibited by field plants vanished in the glasshouse, where nectar composition emerged as a remarkably constant feature across plants, flowers and nectaries. CONCLUSIONS: In addition to corroborating the results of previous studies documenting extreme intra-plant variation in nectar sugar composition in the field, this study suggests that such variation may ultimately be caused by biotic factors operating on the nectar in the field but not in the glasshouse. Pollinator visitation and pollinator-borne yeasts are suggested as likely causal agents.     

Detection of the luteoviruses, beet mild yellowing virus and beet western yellows virus, in aphids caught in sugar-beet and oilseed rape crops, 1990–1993

The incidence of beet mild yellowing luteovirus (BMYV) and non-beet-infecting strains of beet western yellows luteovirus (BWYV) in individual winged aphids, caught in yellow water-traps, in sugar beet during the spring and early summer, and in oilseed rape plots in the autumn, was monitored using monoclonal antibodies in ELISA tests from 1990 to 1993. Between 0% and 8% of the Myzus persicae trapped in sugar beet each year carried BMYV, whereas 0% to 4% caught in oilseed rape in the autumn contained this virus. In 1990, 6.5% of Macrosiphum euphorbiae trapped in sugar beet contained BMYV, but in subsequent years less than 1% were carrying virus. Much higher proportions (26–67%) of the M. persicae tested from sugar beet contained BWYV, and similar proportions tested from oilseed rape (24–45%) also carried this virus in the autumn. In contrast only 3–19% of the M. euphorbiae caught in sugar beet contained BWYV, and none in oilseed rape. In 1991 and 1992 large numbers of Breuicoryne brassicae were caught in the plot of oilseed rape, of which over 50% contained BWYV; none were carrying BMYV. In transmission studies between 1990 and 1992, 1% and 27% of M. persicae transmitted BMYV and BWYV respectively to indicator plants; subsequent ELISA tests on the same aphids showed that 3% and 33% respectively contained the two viruses. One percent of M. euphorbiae transmitted BMYV, but none were found to contain BMYV using ELISA; 15% transmitted BWYV whilst only 5% were found to carry the virus. In 1992 and 1993 the incidence of BMYV-infection in the sugar-beet fields in which aphids had been trapped ranged from 1.2%, in a field which had received granular pesticide (aldicarb) at drilling plus three foliar aphicidal sprays, to 39.5% in a field which had received only one foliar spray. In 1992 in a sugar-beet crop which had received no aphicidal treatments, and where 2.8% of immigrant M. persicae and 2.5% of M. euphorbiae contained BMYV, 11.6% of plants developed BMYV infection. Lowest levels of infection were associated with the use of granular pesticides at drilling. In 1990, 80% of oilseed rape plants in a field plot were infested with a mean of seven wingless M. persicae per plant by mid-December; 37% of these plants were infected with BWYV. The studies show that M. persicae is the principal vector of BWYV, and large proportions of winged M. persicae carry the virus, in contrast to BMYV, which is consistent with the common occurrence of BWYV in brassica crops such as oilseed rape.     

Suppression of Rhizoctonia solani diseases of sugar beet by antagonistic and plant growth-promoting yeasts

AIMS: Isolates of Candida valida, Rhodotorula glutinis and Trichosporon asahii from the rhizosphere of sugar beet in Egypt were examined for their ability to colonize roots, to promote plant growth and to protect sugar beet from Rhizoctonia solani AG-2-2 diseases, under glasshouse conditions. METHODS AND RESULTS: Root colonization abilities of the three yeast species were tested using the root colonization plate assay and the sand-tube method. In the root colonization plate assay, C. valida and T. asahii colonized 95% of roots after 6 days, whilst Rhod. glutinis colonized 90% of roots after 8 days. Root-colonization abilities of the three yeast species tested by the sand-tube method showed that roots and soils attached to roots of sugar beet seedlings were colonized to different degrees. Population densities showed that the three yeast species were found at all depths of the rhizosphere soil adhering to taproots up to 10 cm, but population densities were significantly (P < 0.05) greater in the first 4 cm of the root system compared with other root depths. The three yeast species, applied individually or in combination, significantly (P < 0.05) promoted plant growth and reduced damping off, crown and root rots of sugar beet in glasshouse trials. The combination of the three yeasts (which were not inhibitory to each other) resulted in significantly (P < 0.05) better biocontrol of diseases and plant growth promotion than plants exposed to individual species. CONCLUSIONS: Isolates of C. valida, Rhod. glutinis and T. asahii were capable of colonizing sugar beet roots, promoting growth of sugar beet and protecting the seedlings and mature plants from R. solani diseases. This is the first successful attempt to use yeasts as biocontrol agents against R. solani which causes root diseases. SIGNIFICANCE AND IMPACT OF THE STUDY: Yeasts were shown to provide significant protection to sugar beet roots against R. solani, a serious soil-borne root pathogen. Yeasts also have the potential to be used as biological fertilizers.     

THE VALUE OF GLASSHOUSE TESTS WITH SEEDLINGS IN SELECTING PLANTS TOLERANT TO BEET YELLOWS VIRUS

Commercial strains of sugar beet, and breeders' lines of Beta vulgaris and B. vulgaris subsp. maritima , were exposed to infection with SBY and SBYN strains of beet yellows virus, using varying numbers of Myzus persicae as vectors, so as to cause a wide range of symptoms. The severity of the symptoms was assessed by scoring for superficial veinal necrosis ('etch'). All varieties of sugar beet tested were susceptible to infection, but the severity of the symptoms varied, particularly between the cultivated and wild beet types.
The scores for severity of symptoms made in the glasshouse were positively correlated with similar scores made in a field experiment using two cultivated and two wild beet types. The symptom scores were also positively correlated with losses in root and sugar yields caused by the virus.     

Inherited resistance of sugar beet to aphid colonization

Results of glasshouse experiments have confirmed that inbred lines of sugar beet differ in each of three types of resistance to Myzus persicae Sulz. and Aphis fabae Scop., namely: resistance to settling, resistance to multiplication, and tolerance. Resistance to multiplication was not invariably associated with resistance to settling, although plants of some lines showed both forms of resistance. Plants that were resistant to settling of alatae were not always resistant to apterae of the same species, and there was not a close relationship between resistance to M. persicae and to A. fabae. The mechanisms involved in resistance to aphids in sugar beet are not understood. Progenies of plants, selected for resistance to aphids from inbred lines, were often more resistant than progenies of unselected plants. Inheritance of each type of resistance is probably polygenic. The potential value of the different kinds of resistance, in reducing direct feeding damage and controlling the spread of virus yellows in the field, is discussed. The ultimate breeding objective is to produce commercial varieties in which appropriate kinds of resistance to aphids are combined with resistance to virus yellows. The use of such varieties would reduce the need to control aphids in the field by applications of chemicals.