Characterization and evaluation of landraces of Amaranthus (Amaranthus spp.)

Abstract

The research project entitled “Characterization and evaluation of landraces of amaranth (Amaranthus spp.)” was carried out at the Department of Olericulture and the Department of Plant Biotechnology, College of Agriculture, Vellayani during 2004-2005. The objective of the study was to morphologically catalogue the landraces using the modified descriptor developed from the standard descriptor for amaranthus by IPGRI, to estimate the genetic parameters for different traits in the germplasm for identifying superior lines based on growth, yield, quality and pest and disease resistance and to characterize the landraces using molecular techniques (RAPD analysis). Thirty four accessions for amaranthus were collected from various sources and grown in the field in RBD with three replications. Analysis of variance showed significant differences among the accessions for all the characters evaluated. The yield obtained ranged from 51.67 g (Am13) to 387.22 g (Am 91) and leaf/stem ratio varied from 0.53 (Am 22) to 2.38 (Am 77). The range of values for quality characters were 1269.94 to 4655.54 g 100 g-1 for -carotene, 54.88 to 151.22 mg 100 g-1 for vitamin C, 0.67 to 3.57 per cent for protein, 0.62 to 2.08 per cent for oxalate and 0.04 to 1.62 per cent for nitrate. Incidence of biotic stress ranged from 0 (Am 89 and Am 91) to 2.0 (Am 14 and Am 77) for leaf blight and 0.63 (Am 42) to 2.07 (Am 78) for leaf webber. High PCV and GCV values were obtained for yield characters. Heritability ranged from 38 to 97 per cent. High heritability with high genetic advance was seen for yield and quality characters. All the morphological characters except days to 50 per cent bolting had positive correlation with yield. Leaf blight and leaf webber incidence exhibited negative correlation with yield. Total leaf weight had the maximum direct effect on yield in path analysis. The 34 accessions were split into ten clusters by using D2 statistic. A maximum number of nine accessions were noted in cluster II. Four clusters (Clusters VII, VIII, IX and X) were found to have only one accession each. A maximum intercluster distance of 3097.77 was seen between clusters II and III and intracluster distance was maximum in cluster III. Morphological cataloguing of the landraces based on 20 characters using modified descriptor revealed distinct variations among the accessions for most of the characters. Out of the 34 accessions involved in the study, 27 were selected for RAPD analysis. Screening was done using 38 primers out of which 25 produced amplification. A total of 77 bands were produced out of which 40 per cent (31 bands) were polymorphic and the rest were monomorphic (46 bands). Four primers viz., UBC-17, UBC-18, UBC-23 and OPE-14 gave high level of polymorphism and were chosen for PCR amplification. Maximum polymorphism was seen in case of UBC-23 and maximum number of scorable bands were obtained for UBC-17. The primers gave 39 scorable bands (9.75 bands per primer). The overall similarity coefficients ranged from 0.07 to 0.81. The 27 accessions got divided into two main clusters. The first cluster had nine members and included the three A. hypochondriacus and five A. dubius accessions. A single A. tricolor accession, Am 47 was also seen in this cluster. The second cluster was comprised of the remaining 18 A. tricolor accessions. This distribution revealed the distinct genetic variation between the three different species of amaranthus. It was also evident that the genetic divergence was much higher in A. tricolor compared to the other two species. This higher variation should be exploited to the maximum possible extent in future crop improvement programmes. Using more number of primers for RAPD analysis will make it possible to get more accurate results and this will help in the identification of reliable markers.