Breeding of bread wheat (Triticum aestivum L.) for semi-dwarf character and high yield
K.D. Jamali*, M.A. Arain and M.A. Javed
Nuclear Institute of Agriculture Tando Jam, Sindh, Pakistan
Summary
Lines IN-06-92 and IN-14-92 had the highest grain yields. Line IN-14-92 was comparatively late in days to heading with having higher number of spikelets per spike, higher above-ground biomass production and also increased number of grains per main spike than the check varieties. Individual varietal correlation results suggest that number of grains per spike and spikelet were positively and significantly correlated with main spike grain yield in all the genotypes. Combined correlation results showed that grain weight was negatively and highly correlated with days to heading, number of spikelets and number of grains per spike, however, it exhibited positive correlation with plant height. The important character plot grain yield was not correlated with all the characters under this study except above-ground biomass production.
Key words: semi-dwarfism, agronomic characters, correlation
analysis
Introduction
Semi-dwarf varieties of wheat (Triticum aestivum L.) have been cultivated
in Asia (Japan and Korea) for more than four decades. Their introduction into
Pakistan during 1965 has doubled the yield of wheat crop particularly with the
release of Mexipak variety with the cooperation of CIMMYT Mexico. Universal
acceptance of semi-dwarf wheats followed the pioneering work of Norman Borlaug
whose CIMMYT wheat germplasm features in the pedigree of modern, high-yielding,
semi-dwarf wheat varieties (Gale and Youssefian 1985). The semi-dwarf genotypes
became particularly important with their concurred response to high doses of
chemical fertilizers without lodging. Waddington et al. (1986) who studied more
recent semi-dwarf cultivars (released after 1975), pointed out the importance
of increased kernels per spike and indicated that most recent progress appeared
to raise from increased biomass and not increased harvest index. Allan (1997)
has reported from the studies of near-isogenic lines (NILS) of Nugaines variety
that the semi-dwarf genotypes had mean yields of 22 to 36% greater than the
non semi-dwarf (tall) genotypes. In another genetic backgrounds, yield increases
associated with semi-dwarf genotypes averaged 2 to 16% greater than non semi-dwarf
NILS (Allan 1989). The aim of the present study was to develop semi-dwarf germplasm
with high yield and comparatively better agronomic characteristics for the release
of new varieties.
Materials and methods
The F4.5 lines were each derived from a range of fourteen different crosses during the year 1992 (CIMMYT International Nursery). Four varieties were used as check viz. Sarsabz, Soghat-90, Anmol-91 and Mehran-89. Genotypes were planted in six rows each with the row length of 4.5 meters. The genotypes were grown in a randomized complete block design with four replicates. The data of field experiments were subjected to analysis of variance (Steel and Torrie 1980). Association among the characters were examined by correlation analysis (n=20 for individual varietal correlation, n=72 for combined correlation).