Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes

This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities. The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus-infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL-507 0.2%, SL-509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings.     

Effects of Enhanced UV-B Radiation and Tropospheric Ozone on Physiological and Biochemical Characteristics of Field Grown Wheat

Non-vernalized scions were grafted onto vernalized stocks in winter rape (Brassica napus L. var. oleifera, cv. Górczański). The grafted plants were subjected to electric current (30 V for 30 s or 6 V for 24 h) and the percentage of flowering scions was recorded. The negative polarity with cathode (−) attached to the scion and anode (+) left close to the roots inhibited greatly the percentage of flowering. The reverse polarity enhanced flowering markedly under short days and only slightly promoted flowering under long days. Attachment of electrodes without passing a current had no effect on flowering. This revised version was published online in July 2006 with corrections to the Cover Date.     

The competitive effects of volunteer barley (Hordeum vulgare) on the growth of oilseed rape (Brassica napus)

The effects of competition from volunteer barley (Hordeum vulgare) on the growth and yield of oilseed rape (Brassica napus) were investigated in four experiments over three seasons. The growth of rape in the autumn was reduced by 50 - 91 % by competition from 400 barley plants m^-2. A lower barley density of 200 plants m^-2 had less effect but still reduced growth of rape by 65 - 81% in two of the experiments and 25 - 40% in the other two. During winter and spring the barley decreased in vigour and in the spring the rape started to recover, especially on the early drilled (23 - 30 August) plots. The rape sown in mid-September recovered less quickly. In Experiment 3, herbicides applied in November to control barley did not result in increased growth of rape in winter but led to greater recovery in spring. The barley died during the winter in Experiments 2 and 4, even in the absence of herbicides. Despite the marked effects of barley on the growth of rape in the autumn, yields on plots that had previously contained 200 barley plants m^-2 were reduced by a maximum of only 16% in three of the experiments. In Experiment 3, where the barley was most competitive, this density and 400 plants m^-2 lowered yields by 39% and 78%, respectively. Where a herbicide was used in November to control the barley these yield losses were reduced to 5%. In many rape crops the cost of herbicide treatment would be greater than the financial returns from the expected increase in yield resulting from the control of weeds. Possible reasons for the small loss in yield of rape from barley densities that had substantial effects on the growth of rape in the autumn are discussed.     

Changes of redox activity during the development of rape

Redox activity was measured in vegetative and generative apical parts (5 mm of the stem) and youngest leaves of winter (cv. "G6rczański") and spring (cv. "M?ochowski") rape. Both genotypes were cultured under the same growth conditions (17/15 degrees C day/night, 16 h photo-period), but winter rape was additionally vernalized (5/2 degrees C day/night, 56 days) in order to induce the generative development. The cyclic voltammetric method was used to measure the redox potential of samples in the presence of Fe3+ ions. Changes in the redox activity were compared with changes in riboflavin content and activities of antioxidative enzymes: superoxide dismutase (SOD) and catalase (CAT). The higher level of Fe3+ ions and riboflavin detected in generative apices and leaves of winter and spring varieties indicated that electrons (and their donors) were present at a lower level in these organs in comparison with the vegetative ones. On the contrary, SOD and CAT activity were lower in generative than in vegetative organs. This confirms changes in the redox balance and involvement of oxygen radicals in the generative development of rape plants. The similarity of the measured parameters between winter and spring varieties indicates that the observed changes are independent of the way of generative induction (vernalization). Riboflavin can serve as one of the electron carriers between other oxidation-reduction substances.     

Transfer and segregation of triazine tolerant chloroplasts in Brassica napus L.

Summary Hypocotyl protoplasts of 45 different genotypes of German winter oilseed rape Brassica napus L. (double zero quality: high in yield, seeds low in erucic acid and glucosinolate content) were regenerated to plants. Triazine/triazinone (tri)-tolerant chloroplasts of the Canadian spring oilseed rape variety OAC Triton were introduced into some winter oilseed rapes by means of protoplast fusion. X-ray irradiation was used to limit the transfer of nuclear DNA of Triton protoplasts and to promote the selective transfer of tri-tolerant chloroplasts. Regenerated cybrid plants survived a treatment rate of 1000 g/ha metribuzin. The presence and segregation of the tri-tolerant chloroplasts in winter oilseed rape plants, regenerated from fusion products and their progeny, was investigated by restriction fragment length polymorphism (RFLP). Our results indicate that chloroplast segregation was not completed in plants regnerated from fusion products derived from X-irradiated OAC Triton mesophyll protoplasts and German winter oilseed rape hypocotyl protoplasts. In regenerants and their progeny both chloroplast types can still be present. Chloroplasts derived from wintertype protoplasts can outcompete tritolerant chloroplasts during plant development. In some instances, even progeny plants not kept under selective conditions (metribuzin) lost tri-tolerant chloroplasts. A homogenous population of tri-tolerant chloroplasts was necessary to obtain stable tri-tolerant winter oilseed rape plants.     

Performance of cabbage stem flea beetle larvae (Psylliodes chrysocephala) in brassicaceous plants and the effect of glucosinolate profiles

The cabbage stem flea beetle (CSFB), Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae), is one of the most important pests in European winter oilseed rape production. Adult beetles feed on young leaves whereas larvae mine within the petioles and stems. Larval infestation can cause significant crop damage. In this study, the host quality for CSFB of four oilseed rape (Brassica napus L.) cultivars and seven other brassicaceous species with different glucosinolate (GSL) profiles was assessed under controlled conditions. Larval instar weights and mortality were measured after 14 and 21 days of feeding in the petioles of test plants. To study the impact of GSL on the performance of larvae, the GSL contents in petioles from non-infested and infested plants were analysed before, and 21 days after, the start of larval infestation. Larval performance was not significantly different between the four cultivars of oilseed rape, but differed considerably among the other brassicaceous species tested. In comparison to the weight of larvae in the standard B. napus cv. Robust, the larval weight was higher in turnip rape (Brassica rapa L. var. silvestris) and significantly reduced in white mustard (Sinapis alba L.), oil radish (Raphanus sativa L. var. oleiformis), and cabbage (Brassica oleracea L. convar. capitata var. alba). The duration of larval development increased in white mustard and oilseed radish. The GSL profiles of the petioles showed little difference between non-infested and infested plants of oilseed rape whereas the content of aliphatic GSL increased in the infested turnip rape plants. In contrast, the aliphatic and benzenic GSL decreased in infested Indian rape (B. rapa subsp. dichotoma Roxb.). Larval weight was not correlated with the total GSL content of plants, neither before infestation nor 21 days after. Larval weight was positively correlated with progoitrin and 4-hydroxyglucobrassicin. White mustard, which provides inferior host quality for larval development, has the potential to introduce insect resistance into high-yielding oilseed rape cultivars in breeding programmes.     

The development of an action threshold for cabbage aphid (Brevicoryne brassicae) in oilseed rape in the UK

Replicated small plot field experiments were done at two sites growing winter oilseed rape (ADAS Boxworth, Cambridgeshire and ADAS High Mowthorpe, North Yorkshire) and two sites growing spring oilseed rape (ADAS Bridgets, Hampshire and ADAS Rosemaund, Herefordshire) to investigate the effect of cabbage aphid (Brevicoryne brassicae) on crop yield and quality. All four sites were included in the first 2 yr of the experiment in 1994 and 1995 but only those with winter oilseed rape were continued into the final year in 1996. Plots were artificially inoculated with cabbage aphids at either five aphid 4 m^-2 or 5 aphids 16 m^-2 or left uninoculated to become naturally infested. In 1995 and 1996 the naturally infested treatment was omitted. Sprays of the aphicide pirimicarb at GS 3.3, 3.7, 4.5, 4.9 and 5.5 were used to manipulate aphid populations. Once a plot had been treated at a target growth stage it was sprayed on all subsequent occasions to prevent recolonisation. Aphid numbers were assessed prior to each spray date and their effect on the crop measured in terms of yield of seed and oil and glucosinolate content. Artificial inoculation of aphids was often successful in establishing different populations of the pest at a range of growth stages. Results showed that cabbage aphid sometimes reduced both crop yield and quality. Yield responses to insecticide treatment tended to be larger in spring oilseed rape than in winter oilseed rape mainly because it became more heavily infested at an early growth stage. Tentative thresholds are proposed for control of the pest in both winter and spring oilseed rape. It is stressed that cabbage aphid is a sporadic pest and rarely likely to reach these threshold levels in field crops.     

Effects of previous cropping and fungicide timing on the development of light leaf spot (Pyrenopeziza brassicae), seed yield and quality of winter oilseed rape (Brassica napus)

Light leaf spot, caused by Pyrenopeziza brassicae, was assessed regularly on double-low cultivars of winter oilseed rape during field experiments at Rothamsted in 1990-91 and 1991-92. Previous cropping and fungicide applications differed; seed yield and seed quality were measured at harvest. In each season, both the initial incidence of light leaf spot and the rate of disease increase were greater in oilseed rape crops sown after rape than those sown after cereals. The incidence of diseases caused by Phoma lingam or Alternaria spp. was also greater in second oilseed rape crops. In 1991-92 there was 42% less rainfall between September and March than in 1990-91, and much less light leaf spot developed. However, P. lingam and Alternaria spp. were more common. Only fungicide application schedules including an autumn spray decreased the incidence of light leaf spot on leaves, stems and pods, as indicated by decreased areas under the disease progress curves (AUDPC) and slower rates of disease increase. Summer sprays decreased incidence and severity of light leaf spot on pods only. In 1990-91, all fungicide treatments which included an autumn spray increased seed and oil yields of cv. Capricorn but only the treatment which included autumn, spring and summer sprays increased yields of cv. Falcon. No treatment increased the yields of cv. Capricorn or cv. Falcon in 1991-92. Fungicide applications decreased glucosinolate concentrations in the seed from a crop of cv. Cobra severely infected by P. brassicae in 1990-91, but did not increase yield.     

Factors affecting development of phoma canker (Leptosphaeria maculans) on stems of winter oilseed rape (Brassica napus) in southern England

In winter oilseed rape experiments at Rothamsted in 1997/98 (cvs Lipton and Capitol), 1998/99 (cv. Apex) and 1999/2000 (cvs Apex, Lipton and Capitol), development of crown canker and phoma stem lesions in spring was related to development of phoma leaf spot in the previous autumn/winter. There were differences in thermal time (degree‐days) from the first appearance of phoma leaf spot (autumn) to the first appearance of crown canker (spring) between cultivars (cvs Lipton and Capitol, 1220–1240; cv. Apex, 1120–1140 degree‐days) but not between growing seasons. In 1998/99 and 1999/2000, fungicide (November) treatment delayed the start of crown canker development in the spring but did not affect the rate of increase in severity. In 1997/98, fungicide treatments did not delay the appearance of crown canker but decreased the rate of increase in crown canker severity. In all three seasons, fungicide treatments generally decreased the proportions of plants at harvest with crown canker severity scores 3 or 4 and increased the proportions with scores 0 or 1. There were differences between seasons in the distributions of crown canker severity scores at harvest. The severity of both crown canker and phoma stem lesions increased linearly with accumulated degree‐days in plots with or without fungicide treatment in 1997/98 (cv. Lipton), 1998/99 (cv. Apex) and 1999/2000 (cv. Apex). Regressions showed that severity of crown canker at harvest in July was related to severity in the spring in 1997/98 (early June, cv. Lipton), 1998/99 and 1999/2000 (April, cv. Apex).     

Characteristics of the population build-up of the Russian wheat aphid Diuraphis noxia and the effect on wheat yield in the eastern Orange Free State

Diuraphis noxia infestations were monitored in early winter and winter wheat during 1983–1985. The aphid population increase was logarithmic in all three years and on both cultivars 100 % infestation levels were recorded. The period of exponential increase in both percentage infestation and in the number of D. noxia per stem took place when the plants had reached the stem elongation stage. The mean number recorded at peak population levels was 150–160 aphids per stem. During the period of plant senescence numbers dropped rapidly. Large reductions in yield were recorded on all infested plants. Single-plant data showed that yield reductions in the early winter cv. Betta were related to the duration of infestation. Relative to sprayed controls, reduction in kernel mass ranged from 25–80% and in 1000-kernel mass from 15–45%. However, the yield reductions of the faster-growing cv. Flamink, appeared to be dependent on the number of aphids per plant during the later growth stages and not the duration of infestation.     

The effects of phenotypic plasticity on photosynthetic performance in winter rye, winter wheat and Brassica napus

The contributions of phenotypic plasticity to photosynthetic performance in winter (cv Musketeer, cv Norstar) and spring (cv SR4A, cv Katepwa) rye (Secale cereale) and wheat (Triticum aestivum) cultivars grown at either 20°C [non‐acclimated (NA)] or 5°C [cold acclimated (CA)] were assessed. The 22–40% increase in light‐saturated rates of CO₂ assimilation in CA vs NA winter cereals were accounted for by phenotypic plasticity as indicated by the dwarf phenotype and increased specific leaf weight. However, phenotypic plasticity could not account for (1) the differential temperature sensitivity of CO₂ assimilation and photosynthetic electron transport, (2) the increased efficiency and light‐saturated rates of photosynthetic electron transport or (3) the decreased light sensitivity of excitation pressure and non‐photochemical quenching between NA and NA winter cultivars. Cold acclimation decreased photosynthetic performance of spring relative to winter cultivars. However, the differences in photosynthetic performances between CA winter and spring cultivars were dependent upon the basis on which photosynthetic performance was expressed. Overexpression of BNCBF17 in Brassica napus generally decreased the low temperature sensitivity (Q₁₀) of CO₂ assimilation and photosynthetic electron transport even though the latter had not been exposed to low temperature. Photosynthetic performance in wild type compared to the BNCBF17‐overexpressing transgenic B. napus indicated that CBFs/DREBs regulate not only freezing tolerance but also govern plant architecture, leaf anatomy and photosynthetic performance. The apparent positive and negative effects of cold acclimation on photosynthetic performance are discussed in terms of the apparent costs and benefits of phenotypic plasticity, winter survival and reproductive fitness.     

Endogene Jahresperiodik der Blattbewegungen zweier Oxalis-Arten

Under natural light-dark changes at the Arctic Circle special behaviour was observed in the leaf movement of Oxalis regnellii and Oxalis acetosella: (1) Advancing in the beginning of leaf rising. (2) Prolonging of the duration of day position. (3) Increasing positive phase-andle differences. (4) Prolonging of the duratin of the daily moving-time. From January to April all these features were running back. The winter behaviour has also been shown in artificial light-dark changes (12:12), when plants were taken in the trial before mid winter. The reactions did not occur if the plants were put into artificial light conditions after mid winter. Criterions for an endogenous annual periodicity and its possible annual Zeitgebers under natural light-dark changes are discussed. The positive correlation between the length of day position and the length of day-time in the summer respectively the length of night-time in the winter, as well as positive phase-angle difference in spring and in autumn/winter, are judged as a criterion for a second oscillator.     

Cold-induced changes of enzymes,proline, carbohydrates,and chlorophyll in wheat

Quantitative changes in total leaf soluble proteins, proline, carbohydrate content, chlorophyll fluorescence, guaiacol peroxidase (POD) and catalase (CAT) activities were determined in a less cold-hardy (LCH) spring cv. Kohdasht (LT₅₀ = −6°C), a semi cold-hardy (SCH) facultative cv. Azar 2 (LT₅₀ = −15°C), and a cold-hardy (CH) winter cv. Norstar (LT₅₀ = −26°C) of wheat (Triticum aestivum L.) exposed to 4°C for 9 weeks. Seedlings were grown in a controlled growth room for 14 days at 20°C and then transferred to 4°C (experimental day 0) for 63 days (cold treatment); otherwise they were maintained continuously at 20°C (control treatment). The samples were harvested 0, 2, 21, 28, 42, and 63 days after exposure to 4°C. The results showed significant low temperature (LT)-induced accumulation of total soluble proteins, proline, and carbohydrates and elevation in activities of CAT and POD in leaves of SCH and CH winter cultivars rather than in LCH spring cultivar. In contrast, the chlorophyll fluorescence (F _v/F _m) declined during LT treatment irrespective of cultivar. The results suggest that developmental traits such as vernalization requirement of wheat affects on cold-tolerance expression system of plants.     

Endophytic Bacteria Induce Growth Promotion and Wilt Disease Suppression in Oilseed Rape and Tomato

To determine whether bacteria isolated from within plant tissue can have plant growth-promotion potential and provide biological control against soilborne diseases, seeds and young plants of oilseed rape (Brassica napus L. cv. Casino) and tomato (Lycopersicon lycopersicum L. cv. Dansk export) were inoculated with individual bacterial isolates or mixtures of bacteria that originated from symptomless oilseed rape, wild and cultivated. They were isolated after surface sterilization of living roots and stems. The effects of these isolates on plant growth and soilborne diseases for oilseed rape and tomato were evaluated in greenhouse experiments. We found isolates that not only significantly improved seed germination, seedling length, and plant growth of oilseed rape and tomato but also, when used for seed treatment, significantly reduced disease symptoms caused by their vascular wilt pathogens Verticillium dahliae Kleb and Fusarium oxysporum f. sp. lycopersici (Sacc.), respectively.     

Diagnosis of light leaf spot (Pyrenopeziza brassicae) on winter oilseed rape (Brassica napus) in the UK

Light leaf spot lesions were generally first observed as light green areas on leaves of UK winter oilseed rape crops in January or February and later became brittle and bleached. Elongated lesions, which were brown with indistinct edges, developed on stems in the spring and summer, when lesions were also observed on flower buds, pedicels and pods. Development of diagnostic white pustules (spore masses of Pyrenopeziza brassicae, which erupt through surfaces of infected tissues) for confirmation of light leaf spot infection on symptomless plants or plants with indistinct or ambiguous symptoms in the autumn, winter or spring was enhanced by incubating plants in polyethylene bags. In experiments with artificially inoculated plants, glasshouse-grown plants exposed in infected crops and plants sampled from crops, white pustules developed at all incubation temperatures from 2^oC to 20^oC on infected leaves of different cultivars. The period of incubation required before the appearance of pustules decreased as the time that had already elapsed since the initial infection increased. The longest periods of incubation were required at the lowest temperatures (2^oC or 5^oC) but leaves senesced and abscised from plants most quickly at the highest temperatures (15^oC or 20^oC), suggesting that the optimal incubation temperature was between 10^oC and 15^oC.     

Dehydrin and proline content in Brassica napus and B. carinata under cold stress at two irradiances

The accumulation of cold-induced dehydrin and proline was related to the frost tolerance (FT) in several Brassica species or cultivars. A dehydrin of molecular mass 47 kDa was detected in the leaves of an Ethiopian mustard (B. carinata) and a pair of dehydrins of similar molecular mass in the three (two winter, one spring) oilseed rape (B. napus) cultivars, when plants were maintained at 4 °C for one-month under two different irradiances. More dehydrin was accumulated in oilseed rape than in Ethiopian mustard under the high irradiance. A significant correlation was observed between leaf dehydrin content and FT, and no relationship between proline content and FT or between the proline and dehydrin contents. Protoplast-derived callus cells behaved differently from leaves sampled from intact plants, as they did not accumulate dehydrin and proline in response to cold stress.     

Modulating flowering time and prevention of pod shatter in oilseed rape

Floral induction is a key developmental switch in plants that leads to the production of flowers, fruits and seeds, which are of paramount importance for human life. To meet the demands of several crop harvests per year, or the growth of crop plants in regions with short vegetation times and for the production of ornamental plants, the timing of the floral transition is very important. The discovery of genes that are involved in flowering time control in model plants should allow the modulation of this developmental switch also in plants with economic value. By using a transgenic approach, we showed that a single MADS box gene accelerated flowering and seed ripening in summer rape plants. The MADSB transgene also partially substituted for the strict temperature requirements for flowering in winter rape plants. Transgenic winter rape plants expressing the MADSB transgene also produced more rigid siliques than wild type winter rape plants, and this prevented precocious seed dispersal.     

The effect of electric field on callus induction with rape hypocotyls

The influence of electric field treatment on dedifferentiation and calli formation on rape hypocotyls was investigated. Segments, 10 mm long, of the upper part of rape (Brassica napus L., cv. Góczański) hypocotyls were stimulated by different combinations of voltage/time (1.5 V/120 h, 3 V/3 h, 10 V/15 min and 30 V/30 s) under in vitro conditions. With all electric field treatments, segments oriented with their apical part towards the cathode produced more calli as compared to control (non-treated with electric field). Under opposite orientation slight inhibition of callus growth was observed. As the strongest effect on callus growth was observed after treatment with 30 V/30 s, this electric field treatment was selected for following analyses: the incorporation of [14C]-2,4-D (2,4-dichlorophenoxyacetic acid) and [14C]-BAP (benzylaminopurine) from the culture medium, changes in ACC (1-aminocyclopropane-1-carboxylic acid) level and the redox activity in apical and bottom parts of hypocotyls during 18 d of culture. In contrast to changes in fresh weight, electric field treatment (30 V/30 s) stimulated a higher accumulation of 2,4-D and BAP in basal parts of hypocotyls than in apical ones. Moreover, orienting the apical part towards the cathode resulted in lower uptake of hormones as compared with the opposite orientation. The ACC concentration increased, especially in the basal parts of hypocotyls, independently on electric field application. However, the highest level was observed after electric field treatment with orientation of the apical part towards the anode. The distribution of oxidative substances (measured as the amount of ferric ions) between the apical and bottom part of hypocotyls was not changed when the apical parts were oriented towards the cathode. Under these conditions a decrease in apical and an increase in basal parts was observed during culture. Opposite orientation influenced the redistribution of oxidative substances from the first day of electric field treatment. Based on these results we suggest that electric field action can be connected with its influence on specific concentration of oxidative substances and hormone distribution in cells.     

Transformation of microspore-derived embryos of winter oilseed rape (Brassica napus L.) by usingAgrobacterium tumefaciens

Haploid microspore-derived embryos (MDEs) constitute a unique material for the introduction of new traits into winter oilseed rape (Brassica napus). MDEs have been transformed by usingAgrobacterium tumefaciens strains EHA105 and LBA4404, both carrying the binary vector pKGIB containing theuidA gene encoding β-glucuronidase (GUS) and thebar gene as a marker of resistance to phosphinotricin. Transformed embryos expressed GUS and regenerated plants that were resistant to herbicide Basta, as confirmed by a leaf-painting test. Progeny plants of the transformant T-39 were all transgenic, as they inherited T-DNA from their doubled haploid parental plant. Southern-blot analysis confirmed the integration and transmission of T-DNA into T₁ plants. Transformation of MDEs facilitates the obtaining of winter oilseed rape homozygous for the introduced genes.     

Tentative determination of the molecular weight of substances stimulating the flowering of winter wheat

Murashige & Skoog nutrient was supplemented with substances of molecular weight (M_W) less than 5 kDa, which were separated from extract of winter wheat ears by means of Sephadex G-25 ultrafiltration. Isolated embryos of the same wheat cultivar (Grana) were vernalized in the nutrient for 0 and 7 days at 2 °C for 2 weeks and planted in a glass-house. After 150 days of growth (20/17 °C day/night) the development of the shoot apices was observed. It was found that substances of M_W<5 kDa strongly stimulated the generative development of the plants, enabling the earing of 30 % of non-vernalized plants (control=0%) and 100 % plants vernalized for 7 days (control=29 %). The substances present in the extract of both spring (cv. Jara) and winter (cv. Grana) varieties were fractionated by means of Sephadex chromatography into 300 fractions of M_W=1 to 5 kDa and each of them was added to the isolated embryos of cv. Grana. The embryos were vernalized at 2 °C for 7 days and then cultured as previously described. It was found that the differentiation of the shoot apices was stimulated by over 34 % by fractions of winter wheat extract and more than 50 % by fractions of the spring wheat extract. However, only a few of identical fractions of the extracts of both wheat varieties were able to induce the earing of the plants. These fractions were grouped in 4 continuous intervals of M_W equal to about 4.5–4.9, 3.2–3.3, 2.1–2.6 and 1.00–1.03 kDa. Within the three intervals was identified a small group of identical fractions, which affected the growth of the seedlings in similar mode i.e. inhibiting or stimulating. Thus it can be assumed that these intervals contained identical or similar substances capable of stimulating strongly the earing of winter wheat.