| dc.description | Bread wheat (Triticum aestivum L), the most important cereal crop in the world,
produced extensively in the temperate zones, has now become the second staple
food crop in Bangladesh. Although the country is still a small producer of wheat,
it made spectacular progress in increasing production during post independence to
1985 indicating that the climatic and soil condition of Bangladesh are suitable for
wheat cultivation (Swaminathan, 1986). The wheat area and production in the
country was further increased and reached to the highest peak of 0.85 million
hectares in 1999. The production in that year was 1.9 million tons (Anonymous,
1999). After that, wheat area started decline due to strong competition with high
yielding Boro rice, potato, maize and vegetable crops. In 2009-10, 1.07 million
tons of wheat was produced from an area of 0.37 million hectares, but the yield
was the ever highest 2.9 t/ha (Anonymous, 2010). Current requirement of wheat
in the country is 3.0-3.5 million tons; moreover, wheat consumption is increasing
@ 3% year (Sufian, 2005). In this situation, it is very important to increase
wheat production in the country to reduce huge import costs. | en_US |
| dc.description.abstract | Wheat is the second important cereal crop in Bangladesh and its consumption is increasing day by
day but production is decreasing. Production decrease is mainly due to area reduction for strong
competition with high yielding Boro rice, Maize, Potato and vegetable crops. High temperature at
grain filling stage and Bipolaris leaf blight disease are the major problems of low yield. Besides that,
a new virulent race of stem rust TTKSK (Ug99) identified in Uganda in 1999 has already reached up
to Iran. So, it may comes to Bangladesh also; therefore, the experiment was conducted at the Wheat
Research Centre, Nashipur, Dinajpur with 29 Ug99 tolerant wheat genotypes collected from
International Maize and Wheat Improvement Centre, Mexico with widely adapted variety BARI Gom
21 (Shatabdi) during 2009-2010 to study their variability and select parents for hybridization
programme. There was significant variation for all the thirteen characters studied indicating the
presence of considerable variations for selection. All the genotypes were earlier in heading than
Shatabdi. Many genotypes had higher yields, 1000-grain weight, spikes/m’, harvest index and
agronomic score. Correlation study revealed that spikes/m’, biomass and agronomic score were
positively correlated with yield. Thousand grain weights were also positively and significantly
correlated with plant height, grains/spike and grain filling duration. Waxiness, grain filling duration
and grain yield had high genotypic coefficient of variation coupled with high to moderate heritability
and genetic advance. So, selection on the basis of these characters will be highly effective. Eigen
values of thirteen principal axes and percentage of total variation revealed that first axis accounted
30.69% and first two axes 56.25% variation among the genotypes. Thirty genotypes were distributed
into five clusters with one genotype in group III tol0 genotype in group V. The highest distance from
cluster I was cluster III followed by cluster V. Inter genotypic distance between pairs of genotypes
varied from 0.1014 to 1.1507 indicating the presence of considerable variability in the genotypes. The
highest distance was 1.1507 from Shatabdi to E28 followed by Shatabdi to E30 (1.1068). So,
hybridization of E28 and E30 with Shatabdi will give maximum advantage. Inter-cluster distance was
higher than intra-cluster distance indicating that genotypes of different clusters were more diverse
than those of within cluster. Intra-cluster means for yield, spikes/m’, harvest index and agronomic
score was the highest and heading days was the lowest. All these factors are positive for Bangladesh
condition. So, use of these genotypes in breeding programme will give good output. Spikes/m’,
biomass and harvest index had both vectors positive. So, these characters had the highest contribution
towards the divergence among 30 Ug99 tolerant genotypes. Vector I was positive for heading days,
plant height, grains/spike, 1000-grain weight and grain filling duration. Vector II was positive for
maturity days and grain filling duration. These characters had also good contribution towards the
divergence of the 29 Ug99 tolerant genotypes. | en_US |
