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Subject: Plant Breeding and Genetics × Author: Charan Singh × Start date: 2012 × Type: Thesis × Thesis Type: Ph.D ×
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    Genetic enhancement of grain zinc content in high yielding wheat varieties
    (Punjab Agricultural University, Ludhiana, 2016) Charan Singh; Sohu, V.S.
    Two approaches for genetic enhancement of grain zinc content in high yielding wheat lines was pursued under the study. In the first approach high grain micronutrient content from Triticum monococcum and Triticum boeoticum introgressed into tetraploid (T. durum) background served as donors. The recipient parents utilized were hexaploid high yielding wheat varieties of North Western Plane Zone such as DPW621-50, HD2967 and WH1105 along with two gene pyramided version of PBW343 (carrying rust resistance genes Yr10, Yr15, Lr24, and Lr28). A total 1077 progenies (BC2F2) from different cross combinations were generated and evaluated for grain zinc content other agronomic and quality traits. Analysis of variance for augmented block design revealed that genotypes differed significantly for grain zinc concentration (ppm). A set of highly promising 271 progenies with more than 70 ppm grain zinc concentration and 25 progenies with more than 80 ppm grain zinc concentration were identified. The highest grain zinc and iron concentration was observed in progenies of gene pyramided parent PBW698 with introgression from BF22 used as tetraploid donor. The monitoring of previously mapped grain micronutrient QTL in this cross showed the markers identified at diploid level to be non polymorphic. The second approach followed in this study employed grain micronutrient enhancement via positive association of grain micronutrient and protein content with Gpc-B1 gene, originally derived from T. dicoccoides. A back cross RIL population of 94 Gpc-B1 positive lines derived from cross Glupro/3*PBW568 showing wide variation in protein and micronutrient content and several agronomic traits including plant height and thousand grain weight in a two year evaluation experiment was used in a correlation analysis. Analysis of variation and correlation studies showed that the lines which possess high grain protein content, grain zinc and iron concentration were low yielding with less number of grains per spike, bolder grains, earlier maturity and relatively more plant height. It showed that increase in grain protein content was constrained and a compromise of yield and yield components was observed. Further, yield reduction could arise in more than one ways. For instance, there could be reduction in grain per spike as observed in this study or thousand grain weight as indicated by several reports in the literature. In spite of yield-quality trade off commercially useful product-specific lines can be derived. The relatively tall and early but bold grains lines with exceptionally high protein (15-16%) and micronutrient content (70-80 ppm) in the above studied set can be shortlisted as product specific (bread making) high premium cultivar after further testing. In a second set of experiments under this approach, DPW621-50 derivatives with Gpc-B1 gene were evaluated for yield, yield components and grain zinc content. Pooled analysis of variance and correlation coefficient analysis indicated that Gpc-B1 gene was less effective in high yielding DPW621-50 background. This gene moderately enhanced grain protein content and grain zinc and iron concentration in DPW621-50 derivatives with some reduction in thousand grain weight and grain yield. It was seen that the Gpc-B1 gene must be allowed sufficient flexibility of productivity trait combinations for its protein and grain enhancement effects to be manifested.