PATTERN-ANALYSIS OF THE DIVERSITY OF MORPHOLOGICAL PLANT ATTRIBUTES AND HERBAGE YIELD IN A WORLD COLLECTION OF WHITE CLOVER (TRIFOLIUM-REPENS L) GERMPLASM CHARACTERIZED IN A SUMMER MOISTURE STRESS ENVIRONMENT OF AUSTRALIA
Mzz. Jahufer et al., PATTERN-ANALYSIS OF THE DIVERSITY OF MORPHOLOGICAL PLANT ATTRIBUTES AND HERBAGE YIELD IN A WORLD COLLECTION OF WHITE CLOVER (TRIFOLIUM-REPENS L) GERMPLASM CHARACTERIZED IN A SUMMER MOISTURE STRESS ENVIRONMENT OF AUSTRALIA, Genetic resources and crop evolution, 44(4), 1997, pp. 289-300
Information on the variation available for different plant attributes
has enabled germplasm collections to be effectively utilised in plant
breeding. A world sourced collection of white clover germplasm has bee
n developed at the White Clover Resource Centre at Glen Innes, New Sou
th Wales. This collection of 439 accessions was characterised under fi
eld conditions as a preliminary study of the genotypic variation for m
orphological attributes; stolen density, stolen branching, number of n
odes, number of rooted nodes, stolen thickness, internode length, leaf
length, plant height and plant spread, together with seasonal herbage
yield. Characterisation was conducted on different batches of germpla
sm (subsets of accessions taken from the complete collection) over a p
eriod of five years. Inclusion of two check cultivars, Haifa and Huia,
in each batch enabled adjustment of the characterisation data for yea
r effects and attribute-by-year interaction effects. The component of
variance for seasonal herbage yield among batches was large relative t
o that for accessions. Accession-by-experiment and accession-by-season
interactions for herbage yield were not detected. Accession mean repe
atability for herbage yield across seasons was intermediate (0.453). T
he components of genotypic variance among accessions for all attribute
s, except plant height, were larger than their respective standard err
ors. The estimates of accession mean repeatability for the attributes
ranged from low (0.277 for plant height) to intermediate (0.544 for in
ternode length). Multivariate techniques of clustering and ordination
were used to investigate the diversity present among the accessions in
the co;lection. Both cluster analysis and principal component analysi
s suggested that seven groups of accessions existed. It was also propo
sed from the pattern analysis results that accessions from a group cha
racterised by large leaves, tall plants and thick stolons could be cro
ssed with accessions from a group that had above average stolen densit
y and stolen branching. This material could produce breeding populatio
ns to be used in recurrent selection for the development of white clov
er cultivars for dryland summer moisture stress environments in Austra
lia. The germplasm collection was also found to be deficient in genoty
pes with high stolen density, high number of branches, high number of
rooted nodes and large leaves. This warrants addition of new germplasm
accessions possessing these characteristics to the present germplasm
collection.