No abstract

Lentil (Lens culinaris Medikus) is an important source of protein for people in developing countries. Aphanomyces root rot (ARR) has emerged as one of the most devastating diseases affecting lentil production. In this study, we applied two complementary quantitative trait loci (QTL) analysis approaches to unravel the genetic architecture underlying this complex trait. A recombinant inbred line (RIL) population and an association mapping population were genotyped using genotyping by sequencing (GBS) to discover novel single nucleotide polymorphisms (SNPs). QTL mapping identified 19 QTL associated with ARR resistance, while association mapping detected 38 QTL and highlighted accumulation of favorable haplotypes in most of the resistant accessions. Seven QTL clusters were discovered on six chromosomes, and 15 putative genes were identified within the QTL clusters. To validate QTL mapping and genome-wide association study (GWAS) results, expression analysis of five selected genes was conducted on partially resistant and susceptible accessions. Three of the genes were differentially expressed at early stages of infection, two of which may be associated with ARR resistance. Our findings provide valuable insight into the genetic control of ARR, and genetic and genomic resources developed here can be used to accelerate development of lentil cultivars with high levels of partial resistance to ARR.

Land use (LU) dynamics and its relation to the accelerated soil erosion phenomenon in two broad geomorphic divisions of the Panchnoi River basin of Northeast India have studied. The present study was based on the Revised Universal Soil Loss Equation (RUSLE). To measure the impact of the LU dynamics on soil erosion, the basin was divided into two broad geomorphic divisions, i.e., plain zone and hilly zone, and the rate of soil erosion has been estimated separately for both of the geomorphic divisions. It has been found that in the plain zone, LU dynamics significantly accelerated soil erosion-from 0.52 ton/ha/yr in 1990 to 0.94 ton/ha/yr in 2015. Similarly, the vegetation density decreased significantly in the mountainous and hilly zone as the mean Normalized Difference Vegetation Index (NDVI) value changed from 0.45 in 1990 to 0.35 in 2015, which accelerated soil erosion from 12.06 ton/ha/yr to 18.30 ton/ha/yr from 1990 to 2015. The study indicates that soil erosion may give rise to a severe environmental as well as economic problem in the Panchnoi river basin, which may trigger issues related to the soil fertility of the basin area.

Maize inbred lines were evaluated by using line × tester method involving 11 lines and 3 testers for grain yield and its components through estimation of general combining ability (gca) and specific combining ability (sca) effects. Highly significant genotypic differences were observed indicated wide range of variability present among the genotypes. The crosses with high sca effect for grain yield were evolved from high × low general combiner parents which reveled additive × dominance type of gene action. The cross combinations 9MS4-1 × L22, 9MS4-1 × L486, 9MS4-2 × L431, 9MS4-11 × L486 and 9MS4-15 × L431 with high positive sca effect having high mean values might be used for obtaining high yielding hybrids. The information on the nature of gene action with respective variety and characters might be used depending on the breeding objectives.

Genetic diversity of 27 chickpea genotypes was studied through Mahalanobis D2 and Principal Component analysis. The genotypes under study fall into five clusters. The cluster II contained the highest number of genotypes (11) and Cluster I contained the lowest. Cluster I produced the highest mean value for number of pods per plant. The inter cluster distances were much higher than the intra cluster distances. Cluster V exhibited the highest intra cluster distance while the lowest distance was observed in cluster I. The highest inter cluster distance was observed between cluster I and II while the lowest was between cluster III and V. Considering all the characters, it was suggested that the genotypes BD6549, BD6603, and BD6548 could used as parents for future breeding programs to develop high yielding varieties of chickpea. DOI: http://dx.doi.org/10.3329/bjar.v37i1.11184 Bangladesh J. Agril. Res. 37(1): 129-136, March 2012