Author:
ANNICCHIARICO P.,PIANO E.
Abstract
Six white clover genotypes that were easily distinguishable from each
other on the basis of leaf lamina
marks and morphology were grown at Lodi, Italy, during 1990 and 1991 in dense
swards, under field
conditions and a mowing regime, as (i) pure stands, (ii) a complex mixture of
all genotypes, (iii) binary
mixtures of each genotype with each of two ryegrass varieties, and (iv)
complex mixtures of all clover
genotypes in binary association with each grass variety. The grass components
were of known,
different vigour. The study assessed both intergenotypic and interspecific
interference and related dry
matter yield responses to morpho-physiological traits of the clovers, and
also determined whether a
high level of morpho-physiological heterogeneity conferred a yield
advantage on clover populations.Greater heterogeneity (i.e. a complex mixture of clover genotypes) did
not produce higher clover
yields either in the presence or absence of interspecific interference from
grass; thus, the use of blends
of varieties or the development of varieties with a fairly high degree
of heterogeneity was not
recommended for short-term meadows in environments with relatively low
spatial and temporal
variability. Interactions for yield occurred between clover genotypes and
the presence or absence of
intergenotypic interference (P<0·001), and between clover
genotypes and the presence or absence of
interspecific interference from the grass variety characterized by greater
vigour and aggressiveness
(P<0·01). The variance of the former interaction tended to
be consistently larger than that of the
latter interaction, indicating that competitive effects were greater between
clovers than between the
clover and grass components. A lower Spring [ratio ] Summer yield ratio and taller
canopy tended to confer
a competitive advantage under intergenotypic interference. Relatively
better performance under
interspecific interference was related to higher stolon density, suggesting
that selection for this trait
may increase the general ecological compatibility of large-leaved white
clover types grown with vigorous grass companions.
Publisher
Cambridge University Press (CUP)
Subject
Genetics,Agronomy and Crop Science,Animal Science and Zoology
Cited by
8 articles.
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