Zum Einfluß von Saatzeiten, Saatstärken und Sorten auf agronomische Merkmale von Winterweizen in einem System mit geringer Betriebsmittelzufuhr von außen

The influence of sowing date, seed rate, and variety on agricultural characteristics of winter wheat in a low external input system
Growth conditions of winter wheat in agricultural low external input systems, e.g. ecological agriculture, are very different compared to conventional agriculture (mineral nutrition, impact of diseases, competition of weeds). In 1986, 1987, and 1988 the influence of sowing date and seed rate on crop development and grain production was studied with two varieties of winter wheat in field experiments in Northern Hessia.
Drilling after the first decade of October decreases grain yield of both varieties significantly. The decrease was due to poor emergence, low plant densities, and low grain weights. Tillering could not compensate low plant densities, presumably because of low mineralization of nutrients in cold soils during respective growth stages.
Variation of seed rate (350, 500, and 650 viable seeds/m²) had little influence on grain yield. Low plant densities and low numbers of ears per nr after sowing in the end of October could not be improved satisfactorily by increased seed rates.
The ability of varieties of winter wheat to compensate unfavourable growth conditions due to "late" sowing varies considerably. Cultivars which are able to develop a high plant density seem to be more suitable for delayed sowing dates, as compared to varieties which own a high grain weight.
Further investigations concerning wheat production are needed to optimize agricultural low external input systems. Especially sandy soils with quick response to increased ambient temperature, and sites with favourable growth conditions in late autumn and early spring should be considered.     

Untersuchungen zu Eigenschaften von Winterroggensorten und Triticale in einem Betrieb mit geringer Betriebsmittelzufuhr von außen

Investigations into Characteristics of Winter Rye Varieties and Triticale in a Low External Input System
Low external input systems, e.g. ecological agriculture, are able to solve problems concerning overproduction, diminishing resources, and environmental pollution. The suitability of varieties in ecological agriculture, and the transferability of results of investigations in conventional systems are almost unknown. Field trials with 9 genotypes of winterrye and 1 triticale were conducted from 1984 to 1986 at Neu-Eichenberg. The results can be summarized as follows:
1. The use of modern varieties, and their ability to establish a high plant density was most important to achieve high grain yields.
2. Highest yielding modern cultivars had a very good baking quality.
3. The findings corresponded well with conventionally obtained results.     

Auswirkungen der Züchtung bei Winterweizen in einem landwirtschaftlichen System mit geringer Betriebsmittelzufuhr von außen

Impact of Wheat Breeding in an Agricultural Low External Input System
Low external input systems, e.g. ecological agriculture, are able to solve problems concerning environmental pollution, diminishing ressources, and overproduction. Since growing conditions of winter wheat are very different in ecological agriculture as compared to conventional systems, the impact of genetic improvement of winter wheat in low external input systems is not well known. Investigations were carried out in two years at two ecologically managed farms using 24 genotypes of winter wheat of different periods of release (about 1900 to 1983). The results can be summarized as follows:
1. The tendency towards higher yields among modern varieties as compared to older cultivars in ecological agriculture was highly significant.
2. The rate of yield improvement was smaller under low external input as compared to conventional conditions results. Yield improvement was greatest in recent decades.
3. In ecological agriculture higher yields among modern varieties resulted from an increased harvest index along with an unchanged biomass production, improved resistance properties, and higher ear weight. Reduced plant height probably has negative effects.
4. Baking quality was improved clearly by wheat breeding.
5. Further genetic improvement of winter wheat yields in low external input systems may result from increased biomass production along with a constant or enhanced harvest index, improved resistance properties, increased plant height, and pronounciation of ear weight.     

Untersuchungen zur Ertragsbildung kurz- und langstrohiger Winterweizensorten

Investigations about the yield formation of Winter Wheat Cultivars with Short and Long Straw.
The yield formation of winter wheat cvs with semi-dwarf, short straw and long straw growth habit was investigated over three years in field and glasshouse trials.
The cv with semi-dwarf growth habit had less earbearing tillers and spikelets per ear, an essential lower reduction rate of spikelets and more kernels per spikelet. This cv ranged medium in thousand kernel weight (tkw). Cvs with short straw differed from cvs with long straw through a lower reduction rate of tillers and a lower tkw.
No differences were found in the time of development of generative organs in specific growth phases. Cvs with short straw had advantages in assimilation by means of higher leaf area indices from tiller formation till anthesis and a better light penetration in the canopy due to a more erect leaf orientation. These characters may have been decisive for the higher survival of tillers. The cvs with a long straw however had a higher tkw, properly due to a less compact ear and a higher assimilate gain during kernel filling. Only small differences were found in root growth in favour of the cvs with short straw. The semi-dwarf cv had the shortest roots. The cv "Kanzler" with a long straw had the best drought resistance.     

Erfassung der frischen und trockenen Biomasse und Schätzung der frischen Biomasse von Wintergerste in verschiedenen Regionen Europas mit einem raumgleitergetragenen Radarsensor

The launch of ERS-1, the first operational radar satellite, in 1993, has led to considerable interest in images acquired at radar wavelengths (1–50 cm) as means of gathering information about agricultural crops and their condition. The main advantage of radar systems with respect to optical satellites is that they can acquire images of the earth's surface irrespective of cloud cover, since clouds are transparent at these wavelengths. This is especially important for agricultural applications, where reliably timed images are needed throughout the growing season in order to follow continously the status of the crops as they develop. Multi-frequency polarimetric radar systems represent a convincing evolution of radar systems and their capabilities. The X-SAR/SIR-C radar-instrument, which was flown twice on the space shuttle in April and October 1994, allowed many researchers access to high quality radar images aquired from a space-borne system for the first time. Thus far, the full potential of radar has not been realized, mostly because existing radar satellites such as ERS-1 only aquire information at a single-wavelength and polarization. By restricting the collection of information to a single channel means such images often lack the extra information needed to characterize crops. However, recent studies using multifrequency-radar have shown that vegetation type, structure and condition can be better characterized when data is aquired at several wavelength and polarizations. In order to obtain significant differences in growth stages for identical crop types during the first 10-day long shuttle mission, winter barley fields were chosen along a gradient from southern Italy to southern Germany. These test fields were surveyed coincidentally with shuttle passes over them. One of the main results was that the spread in fresh biomass measured in (g m^?2) between winter barley and maize fields as a function of their different growth stages, could be detected with great precision from the backscatter data. The best parameter for the measurement of winter barley and maize biomass was the ratio HH/VV at L-band. For the extraction of dry biomass in winter barley fields, the cross-polar polarization HV at C-band showed the best results.