Variability in vegitable amaranth (Amaranthus dubius Mart.ex Thell.) for yield, quality and resistance to leaf blight

Abstract

The experiment entitled "Variability 111 vegetable amaranth (Amaranthus Dubius Mart.ex Thell.) for yield, quality and resistance to leaf blight" was conducted at College of Agriculture, Vellayani during the period 2000-2002. The experiment was carried out using 32 diverse accessions of A. dubius and the variety 'Arun' (A. tricolor) as the susceptible check. The objectives were to assess the variability 111 A. dubius germplasm for yield, quality and reaction to biotic stresses, to locate superior genotypes and to confirm the resistance of the accessions to R. so/ani. The ploidy level of the accessions were ascertained by counting the chromosome number. The accessions were grown In the field In RBD with three replications. Analysis of variance of the observations showed significant di fference among the accessions for all the characters. The yield obtained in the range 155.94 (AD 34) to 464.80 g (AD 30). The leaf / stem ratio was in the range 0.93 to 2.48. AD 34 showed late bolting and AD 3 early bolting. The range of values for the quality characters were 9.03 to 23.00 per cent for protein, 5.67 to 15.67 per cent for fibre, 4331.50 to 8915.96 I.U. for vitamin A, 0.62 to 3.8.5 per cent for oxalate and 0.25 to 1.09 per cent for nitrate. AD 34 was organoleptically superior compared to others. All the accessions of A. dubius were free from natural leaf blight incidence. 'Arun' the susceptible check showed PDr of 68.10. To confirm the resistance, artificial inoculation of the accessions was done by raising them in pots in CRD with four replications. Fourteen were immune, 15 were highly resistant and three were moderately resistant. The check variety' Arun' was highly suscepti ble. The accessions AD 14, AD 16 and AD 28 were free from white rust infection. Others showed PDI range 5.77 to 29.39. Sixteen accessions showed minimum infestation of leaf webber with score 1.00. The highest score was 3.00 (AD 11). Higher P'C'V and GeV for most of the characters revealed greater variability. The range of heritability was 67.41 to 99.99. High heritability along with high genetic gain was observed in all the characters. Plant height, stem girth, length of leaf lamina, leaf width, number of branches and days to 50 per cent bolting had positive genotypic correlation with yield. Leaf / stem ratio was negatively correlated. Plant height and leaf width showed high direct effect on yield in path analysis. The accessions AD 30, AD 23 and AD 22 were ranked superior based on the selection index value. The accessions were catalogued morphologically usrng the simplified descriptor developed from IPGRI descriptor. AD 23 is the best compared to AD 30 considering nutritional value, resistance to leaf blight and high organoleptic score. This can be recommended for cultivation in leaf blight endemic areas. The accession AD 28 was found to be resistant to leaf blight and white rust and also with minimum infestation of leaf webber. By crossing AD 23 and AD 28 desirable traits from both can be brought into one.