MARKER ASSISTED RECURRENT SELECTION FOR IMPROVEMENT OF TROPICAL CARROT (Daucus carota L.) FOR NUTRITIONAL QUALITY, NEMATODE RESISTANCE AND VERNALIZATION REQUIREMENT

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Date
2019-08
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University of Horticultural Sciences, Bagalkot
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The present research work was carried out at University of Horticultural Sciences, Bagalkot from 2016 to 2019. A novel breeding scheme, Marker Assisted Recurrent selection (MARS) was designed with an aim to develop an improved carrot variety (Daucus carota L.) for tropical climatic conditions. Considering the overall improvement, both genotypic and phenotypic individual plant selection was carried out for best recombinant from the segregating population. Selection of targeted traits like β-carotene (Y2 and Y-Indel) and reducing sugar (INV) content was done through gene specific markers and nematode resistance (Q1/850 and Q1850Rev2LB) by linked markers but phenotyping for non-targeted root traits. A population C2 has been developed by four diverse founder parents UHSBC- 14, 17, 23-1 and 42-1-1 that are superior in one or two traits. At the end of 3rd recurrent selection cycle genetic gain for total soluble salts (TSS) was 1.30 Brix, 2.00mg/100g of β-carotene, 0.54% increment in total sugar content over earlier two cycles and reducing sugars like glucose and fructose were 0.13%. Power marker analysis revealed the genetic constitution of targets traits in the population. It was observed there was a complete homozygosity (F=1.00) and nil gene diversity (He=0.00) for Y2, Y-indel and INV markers. But for nematode resistance heterozygosity was observed for Q1/850 (0.283) and Q1800Rev2Lb (0.205) and expected heterozygosity was 0.328 and 0.184 respectively. These two markers can be fixed and enrich the population with desirable alleles by next generation of recurrent cycle. The C2 population was superior over founder parents and previous two cycles of population for root weight (96.10 ±6.45g), root diameter (32.37 ±2.43mm), phloem width (0.79 ±0.04cm) as revealed by paired t-test for unequal variances. MARS has shown its effectiveness for both high and low heritable traits with least influence of environment.
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