Growth Of Rape Research Articles

Allelopathy of Aspergillus japonicus on Crops

The seeds of some dicotyledons fail to germinate and grow well when contaminated by Aspergillus japonicus Saito. One strain of A. japonicus isolated from the seeds of contaminated rape (Brassica campestris L.) inhibited the seedling growth of rape and radish (Raphanus sativus L.) when the fungus was directly inoculated on the seed surface. Metabolites released from the fungus inhibited the seedling germination and seedling growth of rape and radish. The culture filtrate and mycelium acetone (C3H6O) extract inhibited the seedling growth of rape. The major allelochemical of A. japonicus was identified by spectroscopic methods as secalonic acid F (SAF). Bioassays showed that SAF at concentration 0.038 mM significantly inhibited the seedling growth of several crops.

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

Abstract 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.

Preparation of N'-[2-(5,6-dimethylbenzothiazolyl)]-N-furfuryloxamide with plant growth regulatory activity.

The reaction of the N-furfuryloxamic acid sodium salt (12) with 1,1'-oxalyldiimidazole (ODI) yielded the imidazolide (13) as an intermediate, and this directly reacted with 2-aminothiazole derivatives (14) or 2-aminobenzothiazole derivatives (15) under essentially neutral conditions to afford the N'-12-(substituted thiazolyl)]- or N'-[2-(substituted benzothiazolyl)]-N'-furfuryloxamides (6 or 7). The prepared compounds (6 and 7) were examined for plant growth regulatory activity in a seed germination assay. The examination resulted in the discovery of some new revelations that N'-[2-(5,6-dimethylbenzothiazlyl)]-N-furfuryloxamide (7c) at the concentration of 1.0 x 10(-3) M completely inhibited the radicle growth of both rape and leek seedlings.

Effects of high plant populations on the growth and yield of winter oilseed rape (Brassica napus)

The effects of plant density on the growth and yield of winter oilseed rape (Brassica napus) were examined in a series of five multifactorial experiments at Rothamsted Experimental Station between 1984 and 1989. Plant densities, manipulated by changing the seed rate and row spacing, or because of overwinter losses, ranged from 13·5 to 372 plants/m2. Normalized yields for the multifactorial plots increased with densities up to 50–60 plants/m2. In very high density plots in 1987/88, yield decreased as density increased >150 plants/m2. Plants grown at high density had fewer pod-bearing branches per plant but produced more branches/m2. Branch dry matter (DM) per plant was decreased by 42%, the number of fertile pods per plant and pod DM/plant by 37%. There was no effect of density on the number or DM of pods/m2. Over 74% of the fertile pods were carried on the terminal and uppermost branches of plants grown at high density in 1987/88 compared with only 34% in plants grown at low density in 1988/89. Seed DM/plant decreased with increase in density but seed size (1000-seed weight) increased. There was no effect of density on seed glucosinolate or oil contents.

Response of oilseed rape plant to low root temperature and nitrate: Ammonium ratios

Oilseed rape (Brassica napus L.) response to root temperature regimes (20/20, 16/8 and 12/12°C day/night) at constant 20°C air temperature was studied. At each regime, three NO3 ‐:NH4 + ratios (10:0, 8:2, or 6:4), at constant 10 mM N, in the irrigation solution were tested. Plant growth, transpiration, ionic composition and level of cytokinins and gibberellins in the xylem exudate were monitored. The two low root temperature regimes, 12/12 and 16/8°C, reduced rape shoot growth by 28 and 22%, and increased the accumulation of soluble carbohydrates by 42 and 26% in the roots, respectively, as compared to the 20/20°C regime. Low root temperatures reduced plants transpiration. The NO3 ‐:NH4 + ratios had no effect on rape growth. At low root temperatures NO3 ‐contents increased in the shoot and decreased in the roots. The sum of cations and that of anions at 12/12 and 16/8°C root temperatures decreased significantly as compared to 20/20°C. The presence of NH4 + in the irrigation solution decreased the concentrations of Ca2+ and Mg2+ in the shoots and roots and increased that of Cl‐ in the shoots and of H2PO4 ‐ in the roots at all root temperatures. Cytokinins and gibberellins contents in the xylem exúdate decreased at the low root temperature regimes. Low root temperature reduced total upward transport of the mineral nutrients and phytohormones, most probably because of reduced water flow through the plant.

Development and evaluation of a CERES-type model for winter oilseed rape

Because of its large N fertiliser requirements and long growth cycle, winter oilseed rape ( Brassica napus L.) is considered to expose its environment to substantial risks of N losses. Soil–crop models provide unique tools to analyse such impacts, with an accuracy that primarily relies on the simulation of crop C and N budgets. Here, we describe a model simulating the growth and development of oilseed rape that was adapted from CERES-N Maize and a previously existing rape model. In addition to its soil components, the model, called CERES-Rape, has modules for crop phenology, net photosynthesis, leaf area development and grain filling, as influenced by crop N status. A new feature compared to previous rape models is the ability to predict the crop's C and N budgets throughout its growth cycle, including losses from leaves by senescence. It also contains a mechanistic description of N translocation from vegetative parts to pods and grains after the onset of flowering. The model has been calibrated on a one-year experiment with three fertiliser N levels conducted in France, and subsequently tested on a similar experiment from Denmark for which no parameters were adjusted. In the vegetative phase, the time course of biomass and N accumulations in the various plant compartments was well simulated, with predicted values falling within one or two standard deviations from the mean in the measurements, except for the low-N treatments for which the high rates of leaf senescence could not be mimicked. After the onset of flowering, some bias appeared in the simulation of crop N uptake which impaired the predictions of final grain N yields. Simulated grain dry matter yields matched observations within ±15% for the calibration data set, but were over-estimated by a factor of 2 for the other data set. Despite the above shortcomings, the simulation of fertiliser effects on the dynamics of crop N uptake and dry matter was judged sufficiently satisfactory to allow an investigation of N losses from rapeseed–cropped soils with the CERES-Rape model.

Evaluation of CECOL, a model of winter rape ( Brassica napus L.)

The CECOL model is a dynamic model that describes the growth and development of winter rape. Here the model is evaluated using a number of different approaches, including sensitivity analysis, investigation of behavior in extreme conditions, graphical analysis and estimation of the mean-squared error of prediction ( MSEP) and its components. The MSEP value gives an overall value of model predictive accuracy. For CECOL, the value is 0.22 (t ha −1) 2. This is somewhat smaller than MSEP of the very simple model that uses the average of past yields to predict future yield. The other evaluation techniques are complementary to MSEP in that they help identify specific types of situation where the model is a poor predictor. Here it is found that the CECOL model predicts flowering dates that are too early for early sowing and too late for late sowing, does not correctly describe the differences between irrigated and nonirrigated treatments, and does not give reasonable values for very low planting densities. In practical terms, these last two errors are not very important.

Effects of simulated and flea beetle injury to cotyledons on growth of drought-stressed oilseed rape, Brassica napus L.

Simulated injury was compared with flea beetle injury on cotyledons of oilseed rape grown at various soil moistures to determine the effects of injury on seedling growth in the greenhouse. The cotyledons of 7-d-old seedlings were injured at 0, 25, 50, and 75% of the total area with a 0.5-mm mechanical pencil or by flea beetles. The soil moisture was maintained at the field capacity, half field capacity, and the permanent wilting point. The growth response of the seedlings was compared for simulated flea beetle injury and soil moisture 7, 14, and 21 d post-injury, and for simulated and flea beetle injury, and soil moisture 7 d post-injury. Simulated injury had the greatest effect on seedlings grown at the field capacity, at 7 d post-injury. At the reduced soil moistures, increased levels of simulated injury were necessary to cause a significant loss in growth. By 14 and 21 d post-injury, compensation to the simulated injury occurred. Simulated injury caused significantly less growth reduction across all injury levels compared with flea beetle injury. However, at injury levels above 25%, both simulated and flea beetle injury had similar trends in growth reduction. The simulated injury tested in these experiments cannot be used in place of flea beetles for resistance screening studies, but may be useful if incorporated as a preliminary tool. Key words: Phyllotreta cruciferae, canola, oilseed rape, injury, damage response

Effects of previous cropping on seed yield and yield components of oil-seed rape ( Brassica napus L.)

Information about the effect of the preceding crop or crop combination on the seed yield of oil-seed rape is extremely scarce. Experiments were carried out in northwest Germany to investigate the effect of different preceding crops on the growth, seed yield and yield components of oil-seed rape. The two directly preceding crops, wheat and oil-seed rape, had only a negligible and non-significant effect on the seed yield of the following oil-seed rape crop. Oil-seed rape grown after wheat had more pods per plant, due to an increase in the number of pods on the higher category branches. In contrast, the seed yield and yield components were more affected by the cropping sequence, i.e. the crops 2 years before. Averaged over two experimental years, the greatest yields were observed in oil-seed rape following the sequence peas-wheat (694 g m −2), whereas the smallest seed yield occurred after 2 years of oil-seed rape cropping (371 g m −2). The differences in the seed yield were again associated with more pods per plant, which compensated for the lower number of plants m −2, whereas the number of seeds per pod and the mean seed weight were almost unaffected by the previous cropping. It was not possible to relate the described differences to the crop development, since differences in the biomass caused by the previous cropping were only significant at maturity. Oil-seed rape grown after 2 years of oil-seed rape had the highest ratings of stem canker ( Leptosphaeria maculans) as well as verticillium wilt ( Verticillium dahliae). But the general level of the diseases was low, and therefore other causes for the effects described must be considered.

Effect of Foliar Applications of Glycinebetaine on Stress Tolerance, Growth, and Yield of Spring Cereals and Summer Turnip Rape in Finland

AbstractCrop losses caused by environmental stresses might be reduced by applying osmoprotectans to crop canopies. Glycinebetaine is endogenously accumulated by some halophytes under stress conditions and represents such a compound. Glycinebetaine was applied exogenously to barley (Hordeum vulgare L.), oat (Avena sativa L.), spring wheat (Triticum aestwum L.), and summer turnip rape (Brassica rapa ssp. oleifera DC.) canopies and its optimal concentration was monitored in the greenhouse. In field experiments the response of crop plants to betaine applications was assessed by measuring accumulation of above ground biomass, leaf area index (LAI), leaf chlorophyll, and yield. The optimum betaine concentration producing advantageous effects on growth and crop physiology in turnip rape was close to 0.1 M and for wheat 0.3 M. Such concentrations promoted accumulation of betaine similar to that of halophytes under stress conditions [ca. 200 μmol (g DM)−1]. In the 1993 field experiment peak LAIs were recorded in irrigated wheat and barley treated with 17.5 kg ha−1 betaine applied at 300 1 ha−1. Green leaf area was slightly more persistent in wheat treated twice with 1 kg ha−1 betaine applied at 200 1 ha−1 in 1994, although it was not associated with increased grain yield. Our results indicated that betaine has no actual potential in Finland for the principal grain crops but further studies are needed in stress prone environments to assess the potential of betaine treatments for preventing crop failures.

The effects of soil sodicity on emergence, growth, development and yield of oilseed rape (Brassica napus)

SUMMARYThe effects of exchangeable sodium on emergence, growth, development and yield composition of oilseed rape were investigated at Buenos Aires, Argentina in 1992. A pot experiment was performed using five exchangeable sodium levels, expressed as Sodium Adsorption Ratio (SAR: 12, 20, 27, 34 and 44). Soil with nine different exchangeable sodium contents (SAR from 0·5 to 50) and seven different particle size distributions (from sandy loam to clay) were used in a parallel trial to study the effect of soil crusting on oilseed rape emergence. Soil crusts were made using a rainfall simulator after seeds were sown. Both experiments showed that the direct effect of sodium on emergence occurred with SAR values higher than those which caused clay dispersion (SAR > 20). Oilseed rape seedlings could penetrate crusts having a resistance of < 230 kPa. At SAR values > 20, main stem growth and yield decreased significantly (P < 0·05). These reductions were counterbalanced by an increase in the number of secondary stems. At SAR levels > 34, stem number, grain number per pod on the main stem, as well as pod number on both main stem and secondary stems, were reduced, leading to a marked reduction in total yield. The most important agronomic effect of soil sodium on oilseed rape would be at emergence stage, due to soil crusting.

Use of a sulphite containing desulphurization product as sulphur fertilizer

AbstractUse of a sulphite containing desulphurization product (TASP) as a sulphur fertilizer had no negative effects on germination or growth of oilseed rape or white cabbage when applied in an amount corresponding to 48 kg sulphite‐S as calcium sulphite per ha, neither when used alone, nor when mixed with animal slurry. The product increased the plant yield when applied on soils poor in available sulphur.

Soil structural and transport properties associated with poor growth of oil-seed rape in soil direct drilled when wet

In a long-term tillage experiment on soil of impeded drainage, heavy rainfall 6 weeks before sowing made soil conditions unfavourable for early growth of oil-seed rape. This resulted in differences in the size, vigour and population of young plants both between treatments and between replicates. The crop was better under conventional mouldboard ploughing and drilling than under either long-term (21 years) of medium-term (6 years) direct drilling. Under direct drilling the crop was poorest in wet and compact replicates. We attempted to identify the soil physical and structural properties which were impairing crop growth. The experimental site was located on a Cambisol and a Gleysol in south-east Scotland. Crop size and vigour were related to visual estimates of field soil structure and to soil transport properties and macroporosities. Infiltration rates were less than 1 mm min −1 and air permeabilities of the top 50 mm of soil were less than 10 μm 2 (at −6 kPa matric potential) in direct drilled areas of low crop vigour. Structural indices were derived from air permeabilities and gas diffusion measurements made in soil cores. These were pore organisation (from air permeability), and pore continuity and the likely dead-end porosity (from gas diffusion). All of these structural indices related well to crop responses. Soil structures favourable to the crop (ploughed and some long-term direct drilled plots) contained well-interconnected macroporosity greater than 0.1 m 3 m −3. Less favourable structure, confined mainly to the medium-term direct drilled plots, contained macroporosity less than 0.1 m 3 m −3, with few channels and a significant proportion of dead-end pores.

Characteristics of a Pythium arrhenomanes with High Frequency in Barley Soils

AbstractSoils from two long‐term crop rotation experiments were examined for incidence of root pathogens with a test tube method, where a great number (hundreds) of small portions (15–68g) of soil were biotested. There was a 4–5 times higher frequency of a root‐infecting Pythium sp. In barley monoculture soil when compared to crop rotation soil, where winter turnip rape was the preceding crop. In pathogenicity tests the isolated pathogen caused severe root rot on barley, wheat and rye, but did not affect growth of oats, maize, peas and winter rape. In all essential morphological characters it resembles P. arrhenomanes and we classify it as belonging to this species.

Effect of drying and rewetting the topsoil on root growth of maize and rape in different soil depths

AbstractThe aim of the present experiments was to determine how fast maize and rape plants respond to drying and subsequent rewetting of the topsoil by changing their rooting patterns in different soil depths. Plants were grown in a glasshouse in large (120 × 10.5 × 5 cm) containers which allowed continuous observation of root growth and control of soil water contents at all depths.In both species, drying of the topsoil resulted in a rapid (after 6 d) decrease of root growth in the topsoil (0–40 cm) and an increase in the subsoil (80–120 cm). Increase of root growth in the subsoil preceded the decrease hi the topsoil. Drying of the topsoil decreased shoot P concentrations in both species, whereas the concentrations of N, K and Ca were not significantly affected despite enriched fertilizer levels in the topsoil. In both species, after rewetting, root growth in the topsoil rapidly recovered, and after 5 d exceeded that of the continuously irrigated plants. This increase of root growth an the topsoil occurred at the expense of root growth in the subsoil.The results demonstrate that maize and rape plants may rapidly respond to drying and rewetting the topsoil by locally increasing root growth in soil layers with the most favourable conditions. This plasticity in root growth is a factor which contributes to the maintenance of an adequate nutritional status.

Efficiency of different methods of irrigation in Indian rape (Brassica napus)

Field experiments were conducted for 3 years (1987–8 to 1989–90) at Regional Research Station, Bathinda—a canal irrigated area of the south-west Punjab. The effect of four irrigation methods: flooding, irrigation to each furrow, to alternate furrows and to furrows between paired crop rows, on water economy, growth and yield of Indian rape was studied. Saving by the water-delivery treatments, in comparison with flood irrigation, was in the order: alternate furrows, single furrows between paired rows, every furrow. Alternate furrow irrigation required about 60 percent of the water for flooding but experienced little loss in productivity.

Alternaria alternata from oilseed rape: mycotoxin production, and toxicity toArtemia salina larvae and rape seedlings

A survey, carried out in Southern Italy on fungi colonizing oilseed rape (Brassicae napua L subspoleifera DC) in the field, showedAlternaria alternata (Fries) Keissler as one of the predominant species. 11 strains ofAlternaria alternata isolated from oilseed rape were cultured on rice to test the ability to produce mycotoxins. All strains produced mycotoxins, including tenuazonic acid (up to 12,000mg/kg), alternariol (up to 200mg/kg), alternariol mortomethyl ether (up to 200mg/kg), altertoxin-l (2 to 250mg/kg), and altertoxin-ll (2 to 70mg/kg). Culture extracts containing tenuazonic acid were toxic toArtemia salina and inhibited seedling growth of oilseed rape. Little or no activity with the same bioassays was shown by culture extracts containing the remaining mycotoxins. No mycotoxins were detected in 16 samples of oilseed rape from processing factories.

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

SummaryThe 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.

Fertilizer placement studies on calcareous and non‐calcareous chernozemic soils: Growth, P‐UP‐take, oil content and yield of Canadian rape

Abstract Field experiments were conducted on calcareous and non‐calcareous Orthic Black Chemozemic soils over a five year period to study the effect of rates and placements of P‐fertilizer on Canadian rape (Brassica napus L. cv Tower) production. Six rates of P as mono‐ammonium phosphate (MAP) were applied at seeding using four placement methods: i) broadcast and cultivated 10 cm into the soil (BC); ii) banded in the seed row with the seed (PWS); iii) banded 2.5 below and 2.5 cm to the side of the seed (PSS); iv) banded 2.5 cm directly below the seed (PBS). Soil type had no significant effect on rape growth, seed yield and P‐uptake. Rape responded best to P‐fertilizer banded with (PWS) or near (PSS, PBS) the seed. But, placing 15 kg/ha P or greater with the seed reduced seedling emergence; with 25 kg P/ha insufficient plants emerged to justify harvesting. The reduced seedling emergence resulted in reduced seed yield and P‐uptake. Maximum yields were obtained when the fertilizer was banded 2.5 cm away from...

THE DETERMINATION AND VERIFICATION OF A BASELINE TEMPERATURE FOR THE GROWTH OF WESTAR SUMMER RAPE

Controlled environment growth cabinets set at mean temperatures of 10, 13.5, 15, 17, 20, 22 and 25 °C were used to determine a baseline temperature of 5 °C for the growth of Westar summer rape (Brassica napus L.). Temperatures in excess of 25 °C caused whole plant sterility. Phenological data obtained from ten field sites, collected over three years, was used to verify the 5 °C baseline temperature. Field growing degree days (GDD) and cabinet GDD were not significantly different. The percent development to physiological maturity (% DPM) of field grown Westar summer rape, as influenced by temperature, was not significantly different from that predicted by the cabinet determined equation. The agreement between field and cabinet GDD and observed and predicted % DPM verified the use of a 5 °C baseline temperature in field GDD equations. % DPM and GDD were found to be better estimators of phenological development in the field than calendar days. A simple linear model, relating % DPM to GDD was developed. It was concluded that temperature is the most important environmental factor regulating the phenological development of Westar summer rape in western Canada.Key words: Westar summer rape, Brassica napus, baseline temperature, phenological development, growing degree days