Dharminder Pathak

Genetic variation for leaf trichome density and its association with sucking insect-pests incidence in Asiatic cotton

Trichomes on the plant body are known to impart resistance/susceptibility to various insect-pests. An intra Gossypium arboreum F2 population between a trichomeless mutant PAUFL 1 and its wild type counterpart was developed to assess the distribution of trichomes on young and mature leaves, and to correlate the trichome density with the sucking insect-pests incidence. Based on pooled data for the years 2011 and 2012, mean trichome count for 552 F2 plants was found to be 47.52 and 90.09 (on 28.27 mm2) for mature and young leaves, respectively. A range of 0–185 and 0–218 trichomes was observed for mature and young leaves, respectively. Significant positive correlation (r = 0.83*) was obtained between trichome density of young and mature leaves. Higher trichome density was observed on young leaves. A positive association between young leaf trichome density and whitefly population was recorded which indicates that higher trichome density is favourable for whitefly incidence and vice versa. However, no correlation between the trichome density of young leaves and jassid population was observed.

Study of genotype x environment interactions and stability among diverse Gossypium arboreum L. genotypes for yield and related traits under North Western Plains

The present investigation was undertaken with an objective to determine the effect of genotype × environment (GE) interactions and stability on Gossypium arboreum genotypes belonging to different part of country for seed cotton yield and related traits. Seventeen Asiatic cotton genotypes were evaluated in randomized block design at Ludhiana, for two years (2010 and 2011) and at Faridkot for one year (2010). The significant genotypes, environments, genotype × environment interactions were observed for all traits. Stability parameters revealed LD694 and LD902 were most stable and significantly outperforming for most of the traits except halo length where DLsa1001 was ahead. Genotypes developed at Punjab were found to be more stable for most of the traits whereas genotypes from other centers can be used as germplasm for pre-breeding programmes.

Development and characterization of an interspecific Gossypium hirsutum x Gossypium armourianum hybrid

Interspecific hybrid between Gossypium hirsutum (AADD) cv. F 1861 and G. armourianum (DD) Acc. PAU 1 was generated and characterized along with parents at morphological and molecular levels. Female parent (F 1861) had erect growth habit, cream petals, palmate leaves, green stem, cream anthers, hairy stem and leaves; whereas male parent (PAU 1) had spreading growth habit, yellow petals, cordate leaves, reddish green stem, yellow anthers and glabrous plant body. The growth habit, petal colour, leaf shape and size of interspecific F1 hybrid were intermediate. Plant stem colour and hairiness, leaf pubescence and anther colour of G. armourianum Acc. PAU 1 were observed to be dominant as hybrid fully resembled Acc. PAU 1 for these characters. Petal spot was absent in F 1861 and present in PAU 1as well as hybrid. Variable expression of petal spot, anther colour and filament colour was observed in F1. The interspecific F1 hybrid was male-sterile. Significant differences were observed between the pollen size of parents as well as parents and their hybrid. Of the 33 SSR markers polymorphic between the parents, 8 markers unambiguously confirmed the hybrid status of interspecific hybrid. This hybrid may serve as a useful genetic resource for the transfer of cotton leaf curl disease resistance to American cotton.