Wirkung verschiedener organischer Düngemittel auf die Effizienz der VA-Mykorrhiza

Effect of different organic manures on the efficiency of VA-mycorrhiza
Under greenhouse conditions, it was examined how different organic manures influence the efficiency of the VA-mycorrhiza Glomus macrocarpum cultivated with Capsicum annuum. The used organic manures: grassmulch, stablemanure as well as 3 different kinds of compost had been added in 5 stages of concentration: 50 , 100 , 150 , 200 and 300 dt/ha.
The mycorrhiza fungi inoculation caused greatest yield and P-uptake increase at the lowest organic manure addition. Higher amounts of all types of manures led to decreasing mycorrhiza efficiencies. This tendency was least pronounced with the grassmulch-variant. How fast this decrease took place was not only dependent on the nutrient contents of the manures. Further important factors of influence were the kind of starting-material, which was used at the compost preparation, and the fact whether the manures were mixed up rotten or not rotten.     

Einfluß verschiedener organischer Düngemittel auf die Effizienz von Azospirillum lipoferum

Effect of several organic manures on the efficiency of Azospirillum lipoferum
Under greenhouse conditions, it was examined how grass mulch, farmyard manure and compost influence the efficiency of Azospirillum lipoferum with Sorghum bicolor. The organic manures were added at 5 concentrations: 0, 50, 100, 200 and 300 dt/ha.
With the exception of the highest amount the grass mulch always induced a good effect of Azospirillum on plant yield and nutrient uptake. The application of farmyard manure or compost did not improve the growth of the inoculated plants. With farmyard manure the inoculation even lowered shoot dry weights. But in both treatments the inoculated plants showed considerably increased N and P contents. In addition to the N₂ fixation the inoculation with Azospirillum lipoferum apparently can increase the capacity of the sorghum plant roots to absorb P. Primarily, the organic manures create better growing conditions for the bacteria and simultaneously serve as P sources.     

Der Einfluß des Nutzungszeitpunktes auf die Effizienz von Mähweidenachsaaten

Efficiency of pasture overseedings as influenced by the date of utilization
Lolieten have a wide range of distribution. High intensity of fertilization lowers the persistence of Lolium perenne. Therefore in intensive pasture management the overseeding of Lolium perenne has gained importance. Many of the aspects with overseeding have been experimentally treated. However, up to now the influence of the date utilization overseeding on the efficiency has not been investigated thoroughly polyfactorial approach. For this reason experiments related to this subject were initiated. They demonstrated that the date of utilization of overseeded Lolieten are of profound importance for the success of overseeding. The alteration within the species-specific yield fractions anticipated by overseeding will require a period of more than one season.     

Der Einfluß der Wachstumsrate auf die Effizienz des produktiven Wasserverbrauches durch die Kulturpflanze unter Berücksichtigung von C3- und C4-Arten

The influence of the growth rate on the water use efficiency by different cultivated plants in consideration of C3- and C4-species
The influence of the growth rate (dry matter production per unit of time) on the water use efficiency by different cultivated plants (maize, sunflower, durum wheat, sorghum, amaranthus) was examined using hydroponic culture. The water use efficiency was expressed by the relative water requirement (1 transpirated water per kg produced dry matter), at which the evaporation was absolutely eliminated. The results showed a definite conformity with the hypothesis, which was taken as the basis for these studies:
– The relative water requirement was not constant on the basis of the changing growth rate during the course of growth and development of the plants. With increasing growth rate decreased the relative water requirement. The effect of the increasing growth rate on the decrease of the relative water requirement was greater all the more, the more the growth rate increased.
– Plants of one and the same species and variety but with different growth rates had different relative water requirements. Those ones with a higher growth rate showed a lower relative water requirement.
An influence of the growth rate on the different relative water requirement of C3- and C4-species also was observed. Under better growth conditions for C3-plants than for C4-plants, the growth rate of C4-plants was slowed down, so the relative water requirement was higher than by C3-species.
Concluding from this research, there is the possibility to employ the growth rate of plants for a measure to use water more efficient in plant cultivation.     

Untersuchungen zum Einfluß von Konkurrenzbedingungen auf die Entwicklung der Bestandesstruktur von Sommerraps

Investigations on the effect of competition on stand structure of spring oilseed rape
On the basis of a field experiment with spring oilseed rape, frequency distributions of plant dry matter and plant height were investigated. Samples were taken at four developmental stages: rosette, begin of flowering, end of flowering, ripeness (harvest). To understand the effect of competition in a plant population on frequency distribution, distance of rows (16 cm, 32 cm) and number of plants (60, 90 and 120 plants/m²) were varied. Differences in frequency distribution were estimated by skewness and kurtosis.
The results show that with age of the plant population the skewness of the plant character dry matter decreases from a high positive value till ripeness to a low positive value; kurtosis also decreases during development and tends to a value of 0 at ripeness. The effect of competition as produced by number of plants for area is mirrored by a positive skewness increasing with increasing number of plants per area. The value for kurtosis also increases with the stronger competition as consequence of plant density. Row distance did not show specific effects of frequency distribution. Plant height did, generally speaking, not react to competition.     

Zum Einfluß von Untersaaten zur Begrünung von Ackerbrachen auf die Vegetationsentwicklung und die Nitratdynamik

The influence of undersown green manure crops for fallows – set-aside land – in view of vegetation-development and the dynamic of nitrate
In view of the establishment of rotational fallows - set-aside land - as well as the bridging of the vegetation-free winter period the suitability of different undersown grasses and legumes m winter cereals was investigated in field trials. Festuca rubra developed well in winter barley and winter wheat. The success of the cultivation of Lolium perenne, Trifolium pratense and Trifolium repens in winter cereals is uncertain because of the risk of light and water deficiences. Dactylis glomerata caused an negative influence on the yield of the cover crop. During the fallow period only low levels of nitrate could be found in the soil. Under fallow tilled repeatedly complete fallow- a nitrate accumulation could be observed during the fallow period. After ploughing up the fallow vegetation, nitrate concentrations - depth 0–150 cm – increased to 60 kg NO₃-N · ha^-1 after the natural fallow without seeding, between 60 and 130 kg NO₃-N · ha^-1 after Trifolium and between 160 and 210 kg NO₃-N · ha^-1 after complete fallow. Lowest nitrate levels were observed from the grass-sites. Undersown Festuca rubra seems to be the best choice in order to compete with weeds, to form a dense sod and to prevent nitrate leaching. In general a seed rate of 8 kg · ha^-1 can be recommended.     

Untersuchungen zum Einfluß von Konkurrenz auf die Bestandesentwicklung von Sommerraps bei unterschiedlicher Gunst der Umweltbedingungen

Investigations on the effect of competition with regard to the stand development of spring oilseed rape as dependent on environmental conditions
Field experiments were conducted to investigate the frequency distribution in spring oilseed rape as dependent on environmental growing conditions and plant density. As measures for frequency distribution skewness and kurtosis were estimated. The plant character determined was single plant dry matter. To understand the changes in the stand structure, samples were taken at the following developmental stages: rosette, begin of flowering, end of flowering and ripeness (harvest). Plant densities ranged from 60 plants/m², 90 plants/m² till 120 plants/m²
The results show that under unfavourable growing conditions, generally speaking, the values of (positive) skewness and kurtosis increase with the development of the plants; under favourable growing conditions, however, the values of skewness and kurtosis decrease from rosette till harvest.
Under unfavourable growing conditions as well as favourable ones, the values of skewness and kurtosis increase with strengthening of plant competition as consequence of increasing plant density. However, the trend during development and the height of the values as well as the quantitative relationships are strongly controlled by the general growing conditions. Frequency distribution, therefore, is not only a result of plant competition but also of differences in resources due to the general conditions of the location.     

Einfluß der Erosion auf die Standortproduktivität im Silomaisanbau

Influence of erosion on productivity of maize ( Zea mays L.) cultivation
Accelerated erosion was monitored in Eastern Schleswig-Holstein (F.R.G.) during the last decades. The objective of this study was to compare agricultural productivity of upper, middle and base slope segments to the respective soil parameters, reflecting results of long-term erosion.
Five soil catenas were surveyed. Each catena was divided into three segments representing an eroded area (upper segment), an area with an equilibrium between erosion, accumulation and soil development (middle segment) and an area with accumulation (base slope segment).
In 1986 soil qualities, growth characters and yield components of maize were analysed for each slope segment. At eroded slope segments vegetation cover and yield were significantly lower than at middle and base slope segments. Middle slope segments (equilibrium between erosion, accumulation and soil development) snowed balanced soil quality parameters and high maize yields with a desired combination of yield components.     

Einfluß von Bodenbearbeitung, Kulturart und Zwischenfruchtanbau auf den Bodenabtrag und den Oberflachenwasserabfluß

The effects of different soil tillage systems, crop rotations and short time cover crops on soil losses and runoff
Soil and water losses were carried out from 1979 to 1986 on a pseudogley-parabrownearth of the farm Ihinger Hof throughout the growth period of green maize and sugar-beet, both planted by plough and rotary hoe. From 1983 to 1986 the effect of short time soil cover crops (October—Dezember) were also studied.
The soil losses under rotary hoe were significantly lower in comparison to plough, but the differences in runoff between the tillage treatments were not significant. Under sugar-beet the erosion caused by rainfall was less than under maize. From the short time soil cover crops, the legume mixtures were found to have the best influence on soil and water conservation, and on the maize growth as well. There was no relationship between runoff or rainfall amount and soil losses. The soil losses correlated strongly to EI₃₀-indices, and this means that the USLE equation of W ischmeier and S mith (1965) can be applied in our experimental Farm in Ihinger Hof.     

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.     

Einfluß des Lichtangebotes auf das Wachstum und die biologische Stickstoff-Fixierung von Weißklee (Trifolium repens L.)

Influence of light quantity on growth and biological nitrogen fixation of white clover ( Trifolium repens L.)
The influence of photon irradiance (E_p; 100 to 500 μmol m⁻² s⁻¹) and of the photoperiod (16 or 11 h) on growth and nitrogenase activity of nodulated white clover plants was studied in growth chambers at two nitrate levels (1.0 and 7.5 mM NO₃⁻).
Total dry mass production, the root proportion and nitrogenase activity increased with increasing E_p and photoperiod. Nitrogenase activity generally increased proportionally to root mass. Only at low E_p (100 μmol m⁻² s⁻¹) and under a short photoperiod (11 h) was the specific nitrogenase activity per unit root mass reduced. An abrupt change in E_p led to a rapid and parallel change in nitrogenase activity and relative growth rate.
A higher NO₃⁻ concentration in the nutrient solution (7.5 mM) led to a marked decrease in specific nitrogenase activity, but increased growth between 200 and 500 μmol m⁻² s⁻¹ during early development only. At 100 μmol m⁻² s⁻¹, there was no growth response to nitrate, although its effect on nitrogenase activity was more marked than at a higher E_p.
The results show that with changing light quantity, biological nitrogen fixation of white clover adapts to the existing demand for nitrogen and does not limit growth except during early development, even when light supply is low.     

Untersuchungen zum Einfluß von Standort, Saatstärke, N-Düngung, Sorte und Erntezeitpunkt auf den Ertrag und die Inhaltsstoffe von Zuckerhirse

Investigations into the effect of location, planting density, N-fertilization, variety and harvest date on yield and contents of sweet sorghum
Looking for high yielding plant species as renewable resources, sweet sorghum ( Sorghum bicolor [L.] Moench) seems to be an interesting crop.
In field trials at three locations in the south-west of Germany in 1983 and 1984 should be investigated the effect of N-fertilization, planting density, variety and harvest date on yield, different morphological characteristics and contents of sweet sorghum.
The results indicate that yields of 15-20 t DM/ha are only feasible when the given temperature sum is higher than 2000 °C (> 5°C). The maximum yield of 22.7 t DM/ha resp. 6.5 t/ha "Free Fermentable Sugar" (FFZ) was realized when a sufficient water supply and N-fertilization had been guaranteed.
The different possibilities of utilization of sweet sorghum e.g. as sugar crop, agricultural raw material for combustion or as forage crop urge the plant breeder to intensify the breeding efforts adapting this crop at the climatic conditions of Germany.     

Einfluß der Bestandesdichte auf Ertrag und Qualität der Zuckerrübe bei unterschiedlichem Erntetermin

The effect of plant population on yield and quality of sugar beet at different harvesting date
Optimum plant population of sugar beet in respect of corrected sugar yield in Central Europe ranges from 70 000 to 90 000 plants/ha. It is known that extending the length of growing period by later harvesting causes an increase in yield and quality of sugar beet depending on location and weather. There is a lack of information, however, about the effect of plant population on yield and quality increase with postponed harvesting date.
The objective of this study was to investigate the influence of plant density and harvesting date on yield and quality of sugar beet.
Four trials were carried out at Göttingen (Lower Saxony) from 1982 to 1985 which included each year four plant populations and three harvesting dates (end of September to middle of November).
Depending on seed lot, plant spacing and field emergence, plant populations varied between 87 000 and 27 000 plants/ha. Averaged over the years, the plant populations for the different treatments reached 71 000, 51 000, 40 000 and 31 000 plants/ha.
Later harvesting date and increasing plant population resulted in higher yield of beet and/or higher sugar content of beet. The increase in corrected sugar yield with extending the length of growing period was highest in plant populations with high density.
From the results it can be concluded that by having the choice, a beet crop with the highest plant population should be harvested at the end, a crop with a lower plant population at the beginning of the harvesting period, unless there have to be observed some other aspects (location, crop sequence, field condition).     

Einfluß eines Wachstumsregulators auf die 'Sink'-Kapazität von Raps (Brassica napus L.)

Influence of a Plant Growth Regulator on the 'Sink' Capacity of Oilseed Rape ( Brassica napus L. )
A pot experiment was carried out to examine the effect of the plant growth regulator Triapenthenol (RSW) on the apical dominance of oilseed rape and its corresponding effect on the plant's 'sink' capacity. RSW's influence on the number of flower primordia, flowers, pods, yield and yield structure of the whole plant and of different fractions of the plant (main shoot, lateral shoots 1–3, lateral shoots >3; 1st, 2nd and 3rd-order lateral shoots) and its effect on gibberellin content and shoot height was measured.
RSW diminished dominance of the main shoot and of 1st-order lateral shoots: the initiation of flower primordia was increased to about 34% and 116%, respectively, in fraction lateral shoots higher than 3 and 3rd-order lateral shoots. Buds developed in a more synchronized pattern leading to a significantly improved number of flowers and pods in fraction lateral shoots higher than 3. Despite an increased number of pods per plant, grain yield remained unchanged because of a decrease in the number of seeds per pod and an unaffected thousand-kernel weight.
A decreased content of gibberelhn A19 (GA19), GA20, GA1 and GA8 was evident after application of RSW, and a correlation between gibberellin-content and shoot height was found.
The results of this study suggest that high levels of such GAs, that primarily promote shoot elongation and strengthen the apical dominance within the plant, limit the plant's 'sink' capacity. These effects may be due to a gibberellin-promoted auxin-synthesis.     

Einfluß von Form und Plazierung der N- und P-Düngung auf Wurzelentwicklung, Phosphat-Aufnahme und Wachstum von Sonnenblumen (Helianthus annuus) und Zuckerhirsen (Sorghum bicolor)

Influence of form and placement of N- and P-fertilisation on the root development, the P-uptake, and the growth of sunflower ( Helianthus annum ) and sweet sorghum ( Sorghum bicolor ).
In pot- and rhizotrone-experiments with Sorghum bicolor and Helianthus annuus , a higher P-uptake was achieved by placement of diammonphosphate (DAP) than by either placement of triplesuperphosphate (TSP) or by broadcasting DAP or TSP, respectively. Dual placement of TSP and ammonia increased the P uptake but it was less effective than placement of DAP for sunflowers, but not for sweet sorghum. Placement of nitrogen resulted in a local root accumulation, where ammonia had a greater effect than nitrate for both of the species. Single placement of TSP had no effect on either P uptake or root development.
Thus, the higher P uptake at DAP placement could be attributed to three main factors: the local root accumulation caused by the placement of nitrogen, a specific physiological ammonia-effect, and the lower binding intensity of the phosphate in the DAP-band compared with placed TSP (W erner and S trasser 1993). The improvement in spatial availability caused by the NH₄⁺ -induced root accumulation was of a greater importance for the P-uptake than was the improvement of chemical availability in the DAP-band. The better response of sunflowers in comparison with sweet sorghum was attributed to better acquisition ability in sweet sorghum.     

Erhaltung der Ertragsfähigkeit des Bodens auf lange Sicht unter dem Einfluß von Fruchtfolgegestaltung, Düngung und Herbizideinsatz

Impact of crop rotation, fertilizer treatments, and herbicidal applications on the long term maintenance of soil fertility
VI. Examination of progressive differences regarding chemical and physical factors of the yield potential of a soil conducted over the period 1973 through to 1983
In order to investigate the influence of different crop management practices such as crop rotation, fertilizer treatments, and herbicide applications on the yield potential of a soil, the Crop Science Department of the Swiss Federal Institute of Technology (ETH Zürich) conducted a long term field experiment commencing 1973. The experimental location was at the Swiss Federal Research Station for Farm Management and Agricultural Engineering at Tänikon/TG (northeastern Switzerland).
Over ten years of research it was found that chemical and physical soil properties had, in general, been only marginally affected by the different experimental treatments. However, consistent studies have shown that certain trends regarding specific factors of greater importance have emerged, which were not observed during the first five year period. Should they persist, the yield potential of the soil could be substantially affected in the long run.
Soil reaction, organic carbon content, cation exchange capacity, and aggregate stability have proven to be relatively stable values. Changes of greater significance were evidenced regarding the character of the air-water regime, a factor of particular importance for this site. Obviously, crop rotation had a marked impact on soil compaction. Therefore under local research conditions, the yield potential of the soil will, in the short term, be most likely endangered by structural soil changes.     

Erhaltung der Ertragsfähigkeit des Bodens auf lange Sicht unter dem Einfluß von Fruchtfolgegestaltung, Düngung und Herbizideinsatz

Impact of crop rotation, fertilizer treatments and herbicidal applications on the long term maintenance of soil fertility
V. Comparative studies regarding chemical and physical factors of the yield potential of a soil over a ten year experimental period
In order to examine the influence of different crop management practices such as crop rotation, fertilizer treatments and herbicide applications on the yield potential of a soil, the Crop Science Department of the Swiss Federal Institute of Technology (ETH Zurich) conducted a long term field experiment commencing 1973. The experimental location was at the Swiss Federal Research Station for Farm Management and Agricultural Engeneering at Tanikon/TG (northeastern Switzerland).
After the ten year period, chemical and physical soil properties were not found to be substantially affected by the various experimental treatments. Organic carbon and total nitrogen were more influenced by fertilizer treatments than by crop rotation and herbicide applications. Both cation exchange capacity and pH proved to be fairly stable values.
Aggregate stability and organic matter exhibited similar profiles, although soil bulk density was affected by crop rotation. The volume of large and medium sized pores was similarly affected in that the corn-dominated crop rotation resulted in a quantifiable impact upon soil compaction.
Depending upon weed control efficiency, the grain yields of the winter wheat test crop clearly exhibited the effects of crop rotation whereas the lowest yields resulted from the corn-dominated crop rotation.     

Einfluß des Stickstoffangebotes auf Wasserverbrauch und Stoffproduktion der Zuckerrübe in Gefäßversuchen

Influence of nitrogen supply on water consumption and dry matter production of sugar beet in pot experiments
This paper describes the influence of nitrogen on water consumption, dry matter production and water use efficiency (WUE) of sugar beet.
The experiments, conducted in 1988 and 1989 using sand culture in pots, included five nitrogen levels from 2 to 16 g/pot.
Beet roots were heaviest where the N-supply was 8 g/pot. Top weight increased considerably up to 16 g N/ pot. Therefore plant dry weight was greatest where the N-supply was maximum. Overall, in 1989 dry matter production (g/pot) was 20 % greater than in 1988 because the beet roots were heavier.
Water consumption increased with nitrogen supply. At the largest N-doses water consumption was 110 1 (1988) and 140 1 (1989). This was three times the amount used at the smallest N-supply. Over the whole season WUE was greatest at 4 g N/pot and lower at both extremes of N-supply. Independently of N-supply, production of plant dry matter per litre of water consumed was between 4.9 and 6.0 g. For root dry matter, equivalent values were 3.7 and 4.6 g/l, and for white sugar yield they were 2.3 and 3.1 g/1     

Einfluß von P-Mangel im split-root-System auf lipoide Eigenschaften der Rapswurzel (Brassica napus L.)

Effect of P-deficiency in the split-root-system on lipoid root characteristics of rape-seed ( Brassica napus L.)
The effect of partial P-deficiency on characteristics of parts of the root system from rape-seed ( Brassica napus L.) was investigated by means of the split-root-technique. At 1 cm length of the seventh leaf treatments started lasting 21 days. Pots were designed with two separated chambers filled up with nutrient solutions. Both halfs of the root system lacked of P (-/-) or were fully fed (+/+). Additionally, one part of the root system was fully supplied while the other part was kept without P (+/-). The root system grown at partial P-supply revealed compensatory reactions which became evident by increased uptake of K and Ca and by higher contents and amounts of lipid-P as compared to the P-deficient root portion. The fatty acid composition of the major phospholipids from root tissue, phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE), varied in dependence of P-nutrition. At P-deficiency the linoleic acid content (% 18:2) declined while the linolenic acid content (% 18:3) increased. Consequently, no change in saturation occurred. However, in PE the degree of saturation was affected distinctly. P-deficiency caused an increase of saturation whereas full supply led to higher desaturation. The results point to relations between the intensity of nutrient uptake modulated by P-nutrition and the amounts and characteristics of membrane lipids in root tissue.     

Einfluß des Stickstoffangebotes auf Substanzbildung, Erntegewicht und Qualität der Zuckerrübe unter besonderer Berücksichtigung von Temperatur und Globalstrahlung in Gefäßversuchen

Influence of nitrogen supply on dry matter production, yield and quality of sugar beet with special reference to temperature and irradiance in pot experiments
The influence of nitrogen on yield and quality of sugar beet has been studied in many experiments. In comparison, little is known about the changes in sugar beet metabolism caused by increasing the nitrogen supply. The experiments described in this series of papers deal with the influence of nitrogen supply on mineral metabolism. This first paper describes the influence of nitrogen on dry matter production, yield and quality of beet with special reference to temperature and irradiance. The experiments, conducted in 1988 and 1989 using sand culture in pots, included five nitrogen levels. These treatments were sampled five times during the season and at harvest time. Overall, in 1989 sugar yield (g/pot) was 30 to 50 % greater than in 1988. In 1989 there was only a little more irradiance and duration of sunshine (7 and 11 % respectively) than in 1988, and the larger yield in 1989 was probably caused by a bright period of four weeks in May/June. Where least nitrogen was supplied, deficiency symptoms appeared in early June. When this happened an ammonium-urea solution was added to the leaves: it increased growth, but not enough to equal the white sugar yield of the treatment where the sand was given the same amount of N at the beginning of the season.