Bal K. Joshi

Diversity Analysis of Tomato Cultivars Based on Coefficient of Parentage and RAPD Molecular Markers

Genetic diversity analysis provides information on the genetic base of the gene pool of released genotypes. The objectives of this study were to assess the diversity of tomato cultivars and breeding lines released from North Carolina State University based on their coefficient of parentage (COP) and RAPD markers, and to estimate the contribution of ancestors to these tomato cultivars and breeding lines. The COP analysis revealed that a single ancestor Walter constituted 25.17% of the North Carolina tomato gene pool followed by Blazer (11.57%) and Fla. 2153 (6.29%). Walter was used in developing 30 lines, whereas Blazer and Fla. 2153 were used in developing 29 lines each. The highest COP value (0.828) was between Summit and Monte Verde, indicating that they were the most similar lines. Similarity coefficients based on the RAPD molecular markers ranged from 0.461 to 0.935, with an average of 0.77. The similarity coefficient of NC3Grape with NCEBR8 was the lowest (0.461), whereas it was the highest (0.935) between NC1CS and NC946. On the basis of molecular data, first and second principal components accounted for 78% and 3.3% of the total variation, respectively. A significant positive correlation (r = 0.19, p = 0.04) existed between two similarity matrices based on the RAPD and the pedigree. This information may be useful for selecting the parents in breeding programs, particularly to widen the genetic base for designing future breeding strategies.

Diversity in proso millet (Panicum miliaceum L.) landraces collected from Himalayan mountains of Nepal

Proso millet (Panicum miliaceum L.) is one of the oldest cereal grains cultivated in the north-western part of Nepal. Not a single proso millet variety has been released so far for cultivation in Nepal. To assess the genetic diversity of proso millet conserved in the National Agriculture Genetic Resources Centre, 42 accessions of proso millet were characterized in Khumaltar (1360 m a.s.l.), Lalitpur in 2015 that were collected from the Humla (1900–2800 m a.s.l.) and Jumla (2300–2600 m a.s.l.) districts of the Western Himalayas of Nepal. Seven quantitative and nine qualitative traits were recorded using standard descriptors. The accessions were found to be diverse using Shannon–Weaver diversity indices (H′) for the quantitative traits of days to heading and maturity, plant height, panicle length, panicle exertion, flag leaf length and grain yield, whereas low diversity was observed for the qualitative traits of leaf sheath colour, flag leaf angle, grain shape, and grain colour, and no diversity was observed for leaf pubescence. The accessions were grouped in five clusters where an accession in Cluster-5 and six accessions in Cluster-4, all from Humla, were found to be high-yielding, early-maturing and of taller plant height. In contrast, 4 accessions in Cluster-2 (3 from Jumla) were low-yielding, late-maturing and of shorter plant height. Accessions H237, H176, H311, H489, H490, H643 and H653, all from the Humla district, performed better in the preliminary evaluation. Although these accessions could be used for future breeding to develop climate-resilient varieties, the genebank could employ an innovative method of using participatory diversity kits to promote farmer selection for immediate benefits.

GGE Biplot Analysis of Tomato F1 Hybrids Evaluated Across Years for Marketable Fruit Yield

Genotypes are generally evaluated in multi-environments to determine their consistent performance across locations and years. Several techniques are available to conduct such valuations. We used GGE biplot technique to understand the genotypic and genotype × year interaction in tomato (Solanum lycopersicum L.). Five F1 hybrids of tomato were evaluated from 2003 to 2008 in North Carolina for total marketable fruit yield. Significant (P < 0.05) genotype × year interaction indicated the necessity of further analysis to select the genotype that had high yield and stability across years. ‘Mountain Fresh’ was the best hybrid as far as yield and stability across years were concerned, followed by ‘Crista’; ‘Mountain Glory’ was highly unstable for marketable fruit yield. We concluded that ‘Mountain Fresh’ could be considered an ideal hybrid that can also be used as control for evaluation of other F1 hybrids. Close association between field performance and GGE biplot findings indicated that GGE biplot is a useful tool to graphically visualize the high-yielding and stable genotypes across years.