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Assessment of genetic potential for breeding Gossypium hirsutum L. for saline conditions

Nabi, Ghulam (2010) Assessment of genetic potential for breeding Gossypium hirsutum L. for saline conditions. PhD thesis, University of Agriculture, Faisalabad .

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Abstract

Responses of 50 varieties/lines of Gossypium hirsutum L. to three NaCl salinity levels i.e., control, 10 dS/m and 20 dS/m, were compared at seedling stage. The results revealed that increase in NaCl salinity, after 30 days growth, considerably affected the growth of roots and shoots, but the effect was more pronounced on roots. Based upon absolute and relative salt tolerance, using root length and shoot length data, three varieties/lines i.e., NIAB 78, B 557 and MNH 522 were found to be salt tolerant, and by contrast Qalandri,MNH 147 and BP52NC63 were found to be salt sensitive. The estimates of broadsense heritability of root length was high, suggested that improvement in salinity tolerance in Gossypium hirsutum L. is possible exploiting the existing variation through selection and breeding. Leaves of six selected lines/varieties grown in control, 10 and 20 dS/m were stored separately for one week in micro-tubes in deep freezer. The concentration of Na+ and K+ ions in the sample were measured with the help of flame photometer. Uptake of K+ in relation to Na+ (K+/Na+) was computed.The tolerant cultivars had lower concentration of Na+ and more concentration of K+ and thus K+/Na+ ratio in the leaves was high than sensitive ones. Genetic diversity in species at molecular level provides an accurate estimate of phenotypic diversity.Random amplified polymorphic DNA (RAPD) fingerprinting technique was used to measure the relationship between six selected parents. It was revealed that three varieties NIAB78, MNH522 and B557 clustered in one group (A), and the other three namely Qalandri, MNH147 and BP52NC63 formed the second group (B). For the development of plant material for genetic studies, six parents were crossed according to diallel crossing system to get F1 seeds. The genetic basis of variation found in responses of accessions/lines to 17.5 dS/m, 20 dS/m and control, 30 F1 hybrids and six parents were allowed to grow upto maturity. The data on plant height, number of bolls per plant, boll weight, ginning percentage, yield of seed cotton per plant, total biomass per plant, staple length, fibre strength, fibre finess, Na+ contents, K+ contents, K+/Na+ ratio and proline accumulation were collected. From the data it is shown that all the characters were found to be controlled by additive properties of the genes at low salinity (17.5 dS/m), whilst boll weight and proline accumulation appeared to be affected by non-additive genes under 20 dS/m salinity. Plant height, number of bolls, boll weight, yield of seed cotton, total biomass, Na+, Na+/ K+ and proline accumulation was revealed to be effected by the additive genes. Although cumulative genes effects appeared to be important in controlling variation in salinity tolerance, dominance acted towards greater NaCl tolerance. This data suggests that possibility of breeding Gossypium hirsutum L. does exist in the material.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Varieties, Assessment, Measure, Gossypium, Relationship, Hirsutum, Computed, Saline, Dominance, Polymorphic, Conditions, Crossing, Breeding, Possibility, Exist, Potential, Genetic
Subjects:Agriculture & Veterinary Sciences(a) > Agriculture(a1)
ID Code:6918
Deposited By:Mr. Javed Memon
Deposited On:11 Aug 2011 11:01
Last Modified:11 Aug 2011 11:01

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