Factors determining the performance of synthetics in Vicia faba L. 1. Heterogeneity,heterozygosity, and degree of cross-fertilization

Summary The relative performance of synthetic varieties in faba beans (Vicia faba L.) as compared with line varieties is the result of the joint effect of several factors. Factors investigated in the present study were (1) effects of heterogeneity and (2) heterozygosity on agronomic performance, (3) genetic variance for the degree of cross-fertilization among inbred lines and (4) genetic variance among homozygous and heterozygous genotypes for yield. The evaluation was based on multilocational trials in Germany with 36 inbred lines and derived entries with contrasting population structure (levels of heterozygosity and heterogeneity). When inbred lines and F₁-hybrids are included in the same mixture of genotypes, the resulting heterogeneity had a positive effect on yield. Relative mid-parent heterosis for yield was between 33% and 51%. The average degree of cross-fertilization was 53.5%, and its genetic standard deviation was 8.3%. The estimates for genetic standard deviation for yield among inbred lines were between 3.4 q/ha and 5.3 q/ha. The highest yielding synthetic variety is expected to outyield markedly the highest yielding line.     

Yield Stability in Faba Bean,Vicia faba L. 1. Variation Among Inbred Lines*

Cultivation of faba beans (Vicia faba L.) is hampered by poor yield stability. The genetic variation at the homozygous level for yield stability in the gene pool of the small-seeded and indeterminate European faba beans and the usefulness of auxiliary traits for the improvement of yield stability were investigated. The concept of stability, based on the regression technique, was applied. A sample of 36 faba bean lines was tested in 16 environments and a subsample of eight lines was tested in 11 additional environments. Significant differences were found between lines for yield stability parameters, but the repeatability of the results was limited. Early maturity correlated markedly (r = 0.51^**) with one of the yield stability parameters (deviation from regression). Although lodging resistance was not correlated with the stability parameters, it proved to be a safety factor for performance.     

Rate and inheritance of cross-fertilization in faba bean (Vicia faba L.)

Summary To assess the feasibility for synthetic varieties of Vicia faba L., 108 faba bean genotypes were screened for cross-fertilization rate in five field experiments carried out in 1989 and 1990 at Wageningen.Significant genotypic differences were observed for outcrossing rate, which ranged from 1 to 55%. These percentages, however, are thought to be not high enough for a commercially feasible production of synthetic varieties.The inheritance of cross-fertilization rate, determined by testing the F₄ generation of a cross between two inbreds, both with high outcrossing rates, appeared to be of a polygenic nature, as was indicated by the wide variation in, and the continous distribution of, the cross-fertilization rates. Among the F₄ lines tested some had a significantly higher cross-fertilization rate than the parents. However, this difference was not found when these lines were retested, indicating that possibilities for successful selection for higher outcrossing rates might be limited.     

Autofertility and Bee Visitation in Winter and Spring Genotypes of Faba Beans (Vicia faba L.)

Differences in the expression of autofertility and in the evidence of attractiveness to bees were investigated in both autumn-sown and spring-sown faba beans. All six winter stocks and one spring stock expressed very little autofertility, with averages of only 10% of flowers and 7% of ovules fertilized when undisturbed. Three other spring stocks, including a closed-flower population, were moderately autofertile, with 22% of flowers and 17% of ovules fertilized when undisturbed. The remaining two spring stocks, both English cultivars, expressed good autofertility, with 50% of undisturbed flowers and 44% of ovules fertilized. Current levels of autofertility in the winter and closed-flower stocks were inadequate to allow the development of a desirable distribution of pods without substantial bee visitation. If levels of autofertility could be raised simply by selection within populations, then they should have been much higher in these stocks. Therefore, autofertile parents will probably have to be included in programmes for breeding cultivars with improved levels of auto fertility. The closed-flower population received significantly less bee visitation than the other stocks in the spring trial. No variation in attractiveness to bees was found among the open-flowered spring stocks, nor among the winter stocks.     

The Nutritive Value of Ten Inbred Lines of Faba Beans (Vicia faba L.) in Relation to their Content of Antinutritional Constituents and Protein Quality

Ten inbred lines of fabe beans (Vicia faba L.) selected according to their quality characters have been investigated for carbohydrates, proteins, and antinutritional compounds. Digestible energy, N-balance trials with growing rats comprising determination of the protein digestibility and biological value were used as criteria in connection with comprehensive chemical-biochemical analysis. The chemical composition of the ten lines showed a considerable diversity as cad the results from the rat crisis. However, the content of vicine and convicine in all or the investigated lines were below the level previously found to have effects on the nutritive value, Starch, protein and fibre were the quantitatively dominating seed constituents, and all showed great variation among the lines. The starch content was not correlated to the quality or nutritive value of the seed, whereas the protein content was negatively correlated to the biological value and net protein utilization. These correlations followed the content of essential amino acids, lysine, threonine and methionine in the faba bean proteins. The content of the sulfur-containing ammo acids cysteine and methionine are especially dominant factors for protein quality. A simple method for total sulphur determination was found nut 10 be a sufficiently reliable technique for evaluating the content of methionine and cysteine in the faba beans. Tannin, insoluble- and total dietary fibre are phenolic aromatic compounds which were negatively correlated with the faba bean quality as expressed by digestible energy, the protein digestibility and the biological value of the faba beans. The results obtained have also revealed, that it is not sufficient to consider tannin as a group in relation to the faba bean quality. We need to separate and evaluate the different types, of phenolics in relation to the variations in quality of faba beans. Some of the low molecular weight (LMW) phenolics in the faba beans seem 10 be involved in inhibitory effects on hydrolase enzymes, chymotrypsin and trypsin. Trypsin and chymotrypsin from different animals were different in their sensitivity to faba bean inhibitors and additional experiments are required to reveal details about these effects. It has also been revealed that fructosans Lind LMW carbohydrates (oligosaccharides) are important in relation to the quality of faba beans.     

Detection and characterization of two new CMS systems in faba bean (Vicia faba) *

Wide crosses were made to identify new cytoplasmic male sterility (CMS) systems in faba beans, based on the interaction of cytoplasm with restorer and maintainer alleles. A total of 330 F₁ hybrids were produced in both reciprocal forms. Male sterile segregates were observed in one reciprocal version in the F₂ generation of six crosses. Two of these crosses with female parents originating from Afghanistan and Egypt expressed stable male sterility in subsequent backcross generations. Based on the female parents of the two crosses, these two CMS systems were designated CMS 199 and CMS 297. CMS 199 was more stable than CMS 297 during backcross generations and across different environments. Maintainer and restorer lines for both CMS systems were identified. Lower expression of male sterility occurred in CMS 297 in the greenhouse during the winter generations than in isolation cages during the summer generations, which may be utilized to maintain male sterile lines by selfing. Regarding practical applications, the CMS 199 shows great promise for hybrid breeding in faba beans.     

Comparison of intra- and inter-pool crosses in faba beans (Vicia faba L.). I. Hybrid performance and heterosis in Mediterranean and German environments

Two recently detected, promising CMS systems in faba bean have opened up new possibilities in hybrid breeding. This study was conducted to determine hybrid performance and heterosis of 33 intra-pool and 66 inter-pool crosses from a factorial of six European small-seeded (Minor), six European large-seeded (Major), and eight Mediterranean faba bean lines. The parent lines and F₁ crosses were evaluated at two German and seven Mediterranean environments for anthesis, maturity, yield, yield components and plant height. Yield in the Mediterranean environments was 60% of that in the German environments. European Minor lines and their intra-pool crosses were unadapted to Mediterranean environments and yielded only 31 % compared with the Mediterranean lines and their crosses, whereas European Major genotypes yielded 58%. In German environments the European crosses yielded 107% of the Mediterranean crosses. Heterotic yield increase over the parental mean was largest for European Minor x Mediterranean inter-pool crosses, amounting to 95% in the Mediterranean and 73% in German environments. Our results confirmed the expectation of an increased heterosis in inter-pool over intra-pool hybrids and poor adaptation of European genotypes in Mediterranean environments. In the latter, Mediterranean intra-pool hybrids were the most promising, whereas in Germany inter-pool hybrids of the European Minor × Mediterranean type were most promising.     

A modified mass selection scheme for creating winter-hardy faba bean (<Emphasis Type="Italic">Vicia faba</Emphasis> L.) lines with a broad genetic base

Winter-hardy faba bean (Vicia faba L.) from northern Europe is represented by a rather narrow gene pool. Limited selection gains for overwintering below ?25 °C have restricted the adoption of this crop. Therefore, the faba bean collection maintained by the USDA-ARS National Plant Germplasm System (NPGS) was utilized to broaden this genetic base by identifying potentially new sources of winter-hardiness using a modified mass selection scheme. From an initial source population, bulk-harvested micro-plots of 466 NPGS accessions, four different bulks were formed by harvesting seeds from plants that survived at four locations representing a range of overwintering selection environments across southeastern Washington. These four bulk populations were then mass selected for three cycles based on winter survival along with a selected group of advanced northern European populations or breeding lines at two southeastern Washington locations with divergent climates. This procedure generated breeding materials with winter-hardiness comparable to the northern European populations. We observed that Northern European populations showed slower annual gains in percent survival (<5%) than NPGS bulks (>5%). Further, the frequency of large seeded populations (>80 g × 100 seed^?1) was reduced over time, suggesting an association between seed size and overwintering. The breeding materials generated by mass selection are useful for the future improvement of faba bean as a fall-sown pulse or cover crop.     

Faba bean breeding for resistance against biotic stresses: Towards application of marker technology

Summary Faba beans are adversely affected by numerous fungal diseases leading to a steady reduction in the cultivated area in many countries. Major diseases such as Ascochyta blight (Ascochyta fabae), rust (Uromyces viciae-fabae), chocolate spot (Botrytis fabae), downy mildew (Peornospora viciae) and foot rots (Fusarium spp.) are considered to be the major constraints to the crop. Importantly, broomrape (Orobanche crenata), a very aggressive parasitic angiosperm, is the most damaging and widespread enemy along the Mediterranean basin and Northern Africa. Recent mapping studies have allowed the identification of genes and QTLs controlling resistance to some of these diseases. In case of broomrape, 3 QTLs explained more than 70% of the phenotypic variance of the trait. Concerning Ascochyta, two QTLs located in chromosomes 2 and 3 explained 45% of variation. A second population sharing the susceptible parental line also revealed two QTLs, one of them likely sharing chromosomal location and jointly contributing with a similar percentage of the total phenotypic variance. Finally, several RAPD markers linked to a gene determining hypersensitive resistance to race 1 of the rust fungus U. viciae-fabae have also been reported. The aim of this paper is to review the state of the art of gene technology for genetic improvement of faba bean against several important biotic stresses. Special emphasis is given on the application of marker technology, and Quantitative Trait Loci (QTL) analysis for Marker-Assisted Selection (MAS) in the species. Finally, the potential use of genomic tools to facilitate breeding in the species is discussed. The combined approach should expedite the future development of lines and cultivars with multiple disease resistance, one of the top priorities in faba bean research programs.     

Significance of Seed Source on Grain Yield in Faba Beans (Vida faba L.) and Dry Peas (Pisum sativum L.)

In order to investigate the significance of seed source on yield and related characters 47 seed lots of seven faba bean varieties and 24 seed lots of five dry pea varieties were tested in three series of field trials. The grain yield of the faba bean varieties tested was considerably modified by seed source, whereas only small and nonsignificant effects of seed source were found in dry peas. In general, seed sources with a high thousand grain weight, a high protein content, high portions of undamaged and healthy seeds, and in faba beans a high degree of cross-fertilization exhibited superior grain yields. Production of high-performance seed proved to be the most difficult for the large-seeded and white-flowered faba bean varieties. Based on a tabular summary on factors affecting effects of seed source problems of seed production in both grain legumes and their impact on yield are discussed.     

Relationship Between Cold Severity and Yield Loss in Chickpea (Cicer arietinum L.)*

Seed yield in chickpea (Cicer arietinum L.) is substantially increased by advancing sowing date from the traditional spring to early winter at low to medium elevation areas around the Mediterranean Sea. This shift, however, increases the probability of the exposure to subzero temperatures as low as -10 °C for up to 60 days in a year. These low temperatures often reduce seed yield of cold-susceptible cultivars. Yield losses from cold were estimated in two experiments conducted at Tel Hadya, Syria. In experiment 1, of 96 genotypes sown on nine dates ranging from autumn to spring during the 1981–82 season, those lacking tolerance to cold were killed and produced no yield in autumn sowing, whereas lines with cold tolerance produced nearly 4 t/ha which corresponds to a four-fold increase over spring sowing. Moderately cold-tolerant genotypes sown during early winter produced substantially more seed yield than the normal spring-sown crop. Seedlings were more cold tolerant than the plants in early or late vegetative stages. In experiment 2, in which yield loss due to cold in the field was estimated in 12 yield trials comprising 288 newly bred lines in the 1989–90 season, the regression of cold susceptibility on seed yield in each of the trials was highly significant and negative. On average, winter-sown trials produced 67 % more seed yield than spring-sown trials, but 125 out of 288 genotypes produced yield more than double in winter sowing. Early maturing lines suffered severe cold damage and many lines produced no seed.     

Crop sequence,crop protection and fertility management effects on weed cover in an organic/conventional farm management trial

A survey of 128 plots, in 2008, of a trial where the effects of crop protection can be separated from those of fertility management, generated weed cover data within six crops (winter wheat, winter barley, spring barley, potatoes, cabbages and a grass/clover ley). The effects of the 2008 crop types, of the two preceding crops and of organic and conventional crop protection and fertility management, were assessed using mixed-effects models and constrained ordination. Cover data for 22 weed species and for monocotyledon, dicotyledon, annual, perennial and total weed cover were used. Cover of 15 weed species, and of the five weed groups, was significantly affected by 2008 crops, with cover highest in spring beans and cabbage. Nine and four weed species 2008 cover were significantly related to crops grown in 2007 and 2006 respectively, as were dicotyledon, annual and total weed cover, but not monocotyledon or perennial cover. Cover of 15 species, and the five groups, was significantly higher in plots with organic crop protection, but only eight species and annuals were significantly affected by fertility management. Crop:crop protection produced the most significant interactions with most cover in organically managed plots. Five species, perennials and total weed cover produced significant three-factor models. The greatest weed cover was in organic crop protected but conventionally fertilised spring barley and the least in totally conventional winter barley. Other factors such as crop density and mechanical weeding also affected 2008 weed cover. The ordination indicated that most of the 22 species were strongly associated with crops from all three years. The sequence of crops in the rotation had a profound effect on weed cover. Where three spring-sown, difficult to weed, crops were grown in sequence (spring beans, potatoes and vegetables, spring barley) weed cover increased. However, cover was limited in grass/clover and some cereal plots with different preceding crops. Models predicting weed cover may need to take into account crop sequences within crop rotations, as well as the more usual management inputs.     

A Rapid Method for Measuring Freezing Resistance in Crop Plants

The objective of this study was to develop a technique based on chlorophyll fluorescence to assess freezing injury and resistance of leaves. Optimization was done with faba bean leaves and applicability to other crops was examined at winter and spring with types of barley, oats, rape and faba beans. Selected leaves from young hardened beans were subjected to standardized freezing tests with different minimum temperatures ( T _min) and fluorescence was monitored. After a dark period basic fluorescence ( F _O was induced by 0.2 μmol m⁻² s⁻¹ pulsed red light and maximum fluorescence ( F _m) was assayed at different light intensities. 1500 μmol m⁻² s⁻¹ rendered to give the maximum possible output of Fm and best differentiation of differently damaged leaves by F _n= F _m - F _O. Leaf temperature during measurement and during a short storage (± 2 h) should be kept at about 0°C to avoid biases between differently damaged leaves. The measuring spot on the leaf must be standardized since fluorescence response differed at the tip and base of a leaflet, but not between the two leaflets of a faba bean leaf. The applicability of F _rr (ratio of F _r of stressed to unstressed leaves) as a measure of resistance was demonstrated by comparison of winter hardiness of cultivars with freezing resistance calculated from the relationship of F _vr and the T _min used in freezing tests.     

Evaluating faba beans for rust resistance using detached leaves

A method was developed for testing detached leavesof faba beans for their response to rust disease.Leaves 5 to 8, counting from the shoot tip, wereexcised and maintained on a water-retaining medium,with 5 ppm gibberellic acid, in an enclosed box in atemperature-controlled glasshouse. Leaves treated inthis way remained in good health for up to 30 days.Rust spores were dispersed in a slurry of talc andwater and applied to the abaxial leaf surface. Diseasedevelopment of seven rust populations, collected fromseveral locations in eastern Australia, was monitoredfor 15 days on eight faba bean accessions. Fouraccessions were BPL lines which ICARDA claimed to havesome resistance, two were ILB lines from ICARDA whichhad been found to have stronger field resistance innorthern New South Wales, Australia, and the remainingtwo were known susceptibles. The detached-leaf testshowed that the two cultivars were susceptible, thefour BPL lines were intermediate and ILB 3107 and ILB3025 were slow-rusting. One rust population, which hadbeen stored under liquid nitrogen for several years,was less effective at inducing disease symptoms thanthe other six, which were all freshly collected. Theinteractions between host accessions and rustpopulations were statistically significant but minor,as the cultivars remained in their categories ofresistance or susceptibility. The detached-leaftechnique is thus suitable for use in screeningindividual plants for reaction to several differentpathogen species or genotypes without danger ofcross-contamination or induced resistance.     

Comparison of intra- and inter-pool crosses in faba beans (Vicia faba L.). II. Genetic effects estimated from generation means in Mediterranean and German environments

Genetic diversity between parents is important for hybrid breeding and for maximum usefulness of a cross in pure line breeding. However, wide crosses may suffer from poor adaptation in the target environments and recombination losses owing to disruption of favourable epistatic gene combinations. In this study we investigated the importance of various gene effects for different traits in the parents and generations F¹ to F⁵ derived from 99 intra- and inter-pool crosses among 20 lines of the Minor, Major, and Mediterranean germplasm pools of faba bean in Mediterranean and German environments. Yield performance of parental inbreds and progenies of crosses in different selfing generations was high in the region of adaptation of the respective germplasm pool. Heterosis for yield was greatest in interpool crosses of Minor × Mediterranean germplasm, amounting to 106% in Mediterranean and 72% in German environments. Interpool crosses exhibited significantly greater heterosis compared with intrapool crosses in both mega-environments. Generation means analysis revealed the importance of additive gene effects and dominance × dominance epistasis in Mediterranean and German environments. Dominance effects and additive × additive epistasis for yield were negligible in most crossing groups. Since intrapool crosses of Mediterranean germplasm in Mediterranean environments and crosses of Minor and Major germplasm in the German environments were most promising, we suggest crosses among adapted germplasm for hybrid breeding and for establishing new base material in line breeding in faba bean.     

Competition, growth and yield of faba bean (Vicia faba L.)

This paper reviews current knowledge regarding the influence of plant density on the growth and yield of the faba bean crop (Vicia faba L.). An analysis is also made of sowing rate and other factors that may modify optimum plant density, including environmental conditions; in this sense, should be made a differentiation between faba crops grown in temperate conditions and those grown in Mediterranean and semi-arid conditions. The genotype also prompts variations in optimum plant density, depending on the botanical type (mayor, equina or minor) and the growth habit (determinate versus indeterminate) of the cultivar selected. Sowing date also influences optimum seeding rate, which is lower for autumn–winter sowing under temperate and Mediterranean conditions and increases as the sowing date is delayed. For the spring-sown crops typical of temperate conditions, optimum plant density will be higher due to the shorter growing season. With a longer growing season and under optimum environmental conditions, there is normally no additional response to densities over 20 plants m⁻², while in suboptimal conditions, optimum plant density may increase to over 60 plants m⁻². Although the faba bean crop displays considerable plasticity in response to variations in plant density, mainly with regard to number of pods per square meter, it is not wholly clear to which component of yield this should really be ascribed. Number of stems per plant appears to be the most influential factor, although further research is required to confirm this.     

Transferability of Chickpea Selection Indices from Normal to Drought-prone Growing Conditions in a Mediterranean Environment*

Chickpea (Cicer arietinum L.) is normally grown as a spring-sown rainfed crop in the Mediterranean region in areas receiving more than 400 mm of rainfall annually. Because of large fluctuations in the total amount and distribution of the rainfall, the crop occasionally suffers from extreme terminal drought. Breeders face a dilemma in selecting materials for both normal moisture regimes and drought conditions because it is often difficult to conduct two parallel breeding programmes. This study examines the transferability of the selection indices (developed as a multiple regression of yield on most influential traits) from one environment to another with the objective of selecting an appropriate environment for the development of cultivars adapted to both environments. Experiments were conducted for 3 years (1989-1991) during the spring at two locations with normal moisture regime (hereafter referred to as drought-free) in Syria and Lebanon and one drought-prone location in Syria. Each year, 192-240 newly bred lines were evaluated in replicated trials for seed yield, days to flowering and maturity, plant height and 100-seed weight. Correlation analyses showed that increased seed size, early maturity and reduced plant height at the drought-prone location and early maturity at the drought-free location were of prime importance in increasing seed yield. Regression equations developed to predict seed yield showed that days to flower and maturity accounted from 67-80 % variation in seed yield at the dry location, whereas at the drought-free locations the contribution of days to maturity was smaller except in 1991 in Lebanon. The percent success in the transferability of the selection indices from the drought-free environments to the drought-prone environment was higher than that from the drought-prone environment to the drought-free environment. These results indicate that chickpea breeding material developed under drought-free environments could be useful under drought-prone conditions. Early-maturing lines selected under normal environments would also perform well under drier conditions.     

Effect of density,cultivar and irrigation on spring sown monocrops and intercrops of wheat (Triticum aestivum L.) and faba beans (Vicia faba L.)

Spring-sown intercrops of wheat (Triticum aestivum L.) and faba beans (Vicia faba L.) were grown in three experiments at the University of Reading, UK. One wheat cultivar, Axona, and one (experiment 1) or two bean cultivars (experiments 2 and 3) Scirocco and Maris Bead, were grown as sole crops and intercrops at 50%, 75% and 100% recommended density. Experiments were rainfed but irrigation was an additional treatment in experiment 3. Biomass and seed yields of both wheat and faba beans were greater when monocropped than when intercropped. There was no evidence that radiation use efficiency (RUE) of intercrops was significantly different from sole crops. In all intercrops there was no significant effect of density on biomass, RUE or seed yield, though there were compensating changes in yield components. Seed yields of Maris Bead were significantly greater than Scirocco in experiment 3 but not experiment 2. There was no significant effect of irrigation on RUE or on wheat biomass and seed yield, but there was a trend for irrigation to increase faba bean biomass (P = 0.07) and seed yield (P = 0.06). With later sowing in experiments 2 and 3, time to harvest was shorter and wheat and bean biomass, seed yield and RUE were reduced. All land equivalent ratio (LER) values for both biomass (maximum 1.23) and seed yield (maximum 1.44) were greater than 1, with one exception in experiment 3, indicating that intercrops of wheat and faba beans make more effective use of land than equivalent sole crops. Partial LERs for faba beans were always lower than those of wheat. The tendency was for highest LERs to occur at 75% recommended density.     

Increasing pre‐acclimation temperature reduces the freezing tolerance of winter‐type faba bean (Vicia faba L.)

Autumn‐sown winter‐type faba bean (Vicia faba L.) has been shown to have a yield advantage over spring sowing. Still, adoption of this overwintered pulse crop remains limited in temperate locations, due to inadequate winter hardiness. This research sought to understand how the prevailing temperature during emergence and seedling development, that is pre‐acclimation, influences freezing tolerance. Seedlings grown under a controlled “warm” 17/12°C (day/night) pre‐acclimation environment were initially less freezing tolerant than those grown under a “cold” 12/5°C temperature treatment. Stem and particularly root tissues were primarily responsible for slower cold acclimation, and there was a genotype specific response of above‐ground tissues to pre‐acclimation treatment. Both above and below‐ground tissues should be tested across a range of pre‐acclimation temperatures when screening faba bean germplasm for freezing tolerance.     

Vorfruchtwirkungen verschiedener Blattfrüchte auf Winterweizen und Einfluß von Anbaumaßnahmen

Effects of preceding "break crops" on winter wheat and influence of cultural practices
Between 1979—83 there was tested the effect of 5 "break crops" (biennial alfalfa, clover-grass, faba bean, winter-rape, silomaize) on succeeding winter wheat and the interaction with changed cultural practices such as N-fertilization and conventional or reduced primary tillage (plough ↔ rotary tiller).
After the break crops wheat yield decreased within a range of 4 dt/ha as follows: alfalfa → beans → rape/ clover-grass/maize. Raising N-fertilization hardly allowed to improve the value of the break crops; most likely that of maize and with rotavating. Adaption of N-dressings promised greater influence.
The manner of primary tillage exerted stronger influence on the yield than the level of N-fertilization. Concerning long-term yield the rotary tiller equaled the plough after 4 break crops; after faba bean it was superior. Increasing N-fertilization tendentially favoured the rotary tiller after bean, rape and maize. Using the rotary tiller, at beginning of growth there may be calculated on 15 % higher NO₃-values and/or higher N-mineralization or N-transformation.
Eyespot disease could not be prevented sufficiently and purposefully by an other break crop, N-fertilization or primary tillage. Recurrent rotavating suppressed weed less than ploughing.