|Keywords (Extracted from title, table of contents and abstract of thesis)
glutenin, wheat (triticum aestivum l.), genetic diversity, food security, afghanistan, pakistan, days to heading, days to maturity, grain filling period, number of productive tillers per plant, peduncle length, flag leaf area, plant height, spike length, number of spikelets per spike, biomass per plant, grain yield per plant, 1000-grain weight, protein percentage, harvest index percentage, growth habit, glume pubescence, awn color, awnedness
Wheat (Triticum aestivum L) germplasm comprising of 143 accessions collected from Afghanistan and Pakistan was evaluated in field for two yeas, 2000-2001 and 2001-2002 at Experimental Farm of National Coordinated, Wheat program, National Agricultural Research Center, Islamabad. Fourteen quantitative traits viz. days to heading, days to maturity, grain filling period, number of productive tillers per plant, peduncle length, flag leaf area, plant height, spike length, number of spikelets per spike, biomass per plant, grain yield per plant, 1000-grain weight, protein percentage, harvest index percentage, and four qualitative traits viz. growth habit, glume pubescence, awn color and awnedness were recorded. Mean, range, standard deviation and coefficient of variation were computed for each quantitative trait to estimate the extent of agro-morphological genetic diversity present in the accessions. Significant amount of genetic variation was observed for days to maturity, grain filling period, number of tillers per plant, peduncle length, plant height, spike length, 1000-grain weight, seed protein percentage and grain yield, whereas spikelets per spike, biomass per plant, harvest index and flag leaf area showed less variation. The magnitude of genetic variation for qualitative traits like growth habit, awn color and awnedness was reasonable, while low amount of variation was observed for glume pubescence, as majority of accessions (9161%) were without glume hairs.
Correlation among the quantitative traits revealed that days to heading and days tomaturity were significantly correlated with protein percentage, and number of productive tillers per plant, and flag leaf area had positive correlation with plant height, whereas plant height showed strong correlation with peduncle length. 1000-grain weight was highly correlated with harvest index but negatively correlated with protein percentage. High correlation coefficient between the years 2001 and 2002 for the average performance of the quantitative traits revealed that there were less environmental effects on the traits over the years suggesting a need to evaluate the wheat accessions in different agro-ecological regions rather than over the years.
The accessions collected from mountainous regions of Afghanistan and Pakistan showed late maturity, were tall statured, had longer peduncle length, more spikelets per spike, medium 1000-grain weight and spike length. Medium performance of the accessions for 1000-grain weight and higher protein percentage. The two complimentary procedures namely Principal Component Analysis and Cluster Analysis were used in this study to describe phenotypic variation among the accessions. The principal components of wheat accessions having greater than I eigen value contributed more than 70% genetic variation. The contribution of genetic diversity by first three PCs was above 60% during both the years. The PC, accounted for 39.79% variation and was positively associated with majority of the traits. The characters, which contributed more positively to PC, were harvest index, grain yield per plant, 1000-grain weight, peduncle length, grain filling period, plant height and biomass per plant. The clustering of accessions on the basis of morphological similarities grouped them into seven clusters in both the years. It was observed that none of the cluster included all the accessions from the same region or adjacent regions. The scatter diagram based on average genetic diversity revealed that accessions from Northern Areas and Baluchistan of Pakistan and greater dissimilarities than those from Punjab, Sindh and AJK regions.
A considerable variation for HMW Glutenin Sub-units was noticed when accessions from each of the seven regions were treated as mega populations. In total 17 different HMW glutenin subunit compositions were found. The frequency of Null and 2+12 alleles was the highest in the entire set of germplasm. During the present study six accessions (PAK 17647, PAK 17336, PAK 16200, PAK 17620, PAK 17627 and PAK 16082) possessing 5+10 allele, which is a known source for good bread making quality, were identified. All the accessions from Sindh were found to possess 2+12 alleles at Glu-Dl, showing poor genetic diversity at this locus.
The present study provides a comprehensive set of database both for the accessions from various regions of Afghanistan and Pakistan. The variation present in the accessions can successfully be used by the molecular biologist and by the breeders for the varietal development program.