Agriculture Reference
In-Depth Information
against weeds, there can be a problem with selection the varieties to organic and other less
intensive crop production systems.
Christensen's study [7] showed no significant correlation between yield and competitive
ability of cereal varieties against weeds, which means that both of these features should be
considered by breeders in selecting varieties for organic farming system. Promising might be
the selection for genotypes with high early nitrogen uptake efficiency amongst those already
recognised as having good coverage and shading ability [4].
The aim of the research was to compare the yields of several winter and spring wheat varieties
cultivated in organic and conventional crop production systems to identify the causes of yield
differentiation in these systems.
2. Material and methods
The study was conducted in 2008-2010 at the Experimental Station of Institute of Soil Science
and Plant Cultivation - State Research Institute in Puławy, Poland (N:51°28', E:22°04) in an
experiment, in which different crop production systems have been compared since 1994. The
experiment was located on a Luvisol, a loamy sand and on a sandy loam. The characteristics
of agricultural practices used in each system were presented in Table 1.
The area of each crop rotation field was 1 ha. Within the field of winter and spring wheat, the
experiment with different varieties was established in completely randomized blocks. Five
modern varieties of common wheat ( Triticum aestivum ssp. vulgare ): Kobra Plus, Bogatka,
Smuga, Tonacja, Ostka Strzelecka and old variety of spelt wheat ( Triticum aestivum ssp. spelta )-
Schwabenkorn were cultivated. Nine spring wheat varieties: Bombona, Vinjett, Parabola,
Tybalt, Nawra, Raweta, Bryza, Żura, Zadra were tested in organic system. In conventional
system 4 varieties of winter wheat: Kobra Plus, Bogatka, Rywalka, Legenda and 4 varieties of
spring wheat: Bombona, Parabola, Tybalt and Vinjett were cultivated. The varieties of common
wheat were sown at a rate of 220 kg grains · ha -1 , spelt wheat - 200 kg of spikelets· ha -1 , spring
wheat - 190 kg grains · ha -1 . In conventional system spring wheat was cultivated in pure stand
whereas in organic system it was sown with undersown crop (common clover - 10 kg
ha -1 +Dutch clover 3 kg ha -1 +meadow fescue 10 kg ha -1 +perennial ryegrass 10 kg ha -1 ). According
to organic agriculture rules, mineral nitrogen fertilizers and chemicals were not used. In winter
wheat canopy weeds were controlled in mechanical way, using a weeder, two or three times
in spring, at tillering stage, whereas in spring wheat mechanical weed control was not applied
due to undersown plants. In conventional farming system chemical plant protection was
applied (Table 1).
High differences in weather conditions were observed during the research period (Table 2).
The growing season of 2007/2008 was characterized by favourable weather conditions for
growth and development of winter wheat and spring wheat. Precipitation slightly higher than
average was well distributed. Suitable thermic and moisture conditions reflected in the
development of dense wheat canopies of large ability to compete with weeds. The spring of
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