Bhanwar Singh

Genetic combining ability for concentration of mineral elements in cabbage head (Brassica oleracea var. capitata L.)

Brassica vegetables are important source of dietary nutrition. However, information on the genetic combining ability of mineral elements such as iron, zinc, copper, manganese, potassium and calcium or their types of genetic effects (i.e. additive or non-additive) is scarce but important as it influences the selection of parents and breeding approaches to be adopted for improvement of nutritional quality of cabbage. Therefore, an attempt was made to estimate combining ability in a linexa0×xa0tester (5xa0×xa011) mating design for minerals. Significant mean square for linexa0×xa0tester interaction was observed for all minerals under study indicating the prevalence of non-additive variance; while less than unity value of σgca2 /σsca2 ratio for iron, zinc, manganese, potassium and calcium accumulation indicate predominance of non-additive gene action. The parents 83-2, Pride of Asia, Pusa Mukta, Red Cabbage and MR-1 were found good general combiners for four mineral elements. The general combining ability effects of the parents for various minerals revealed that none of the parents excelled for all the minerals suggesting the need for multiple crossing approaches. The cross 83-1xa0×xa0AC-1019 (Poorxa0×xa0Poor general combiner) exhibits desirable significant specific combining ability effects for all six minerals might be due to presence of high magnitude of non-additive especially complementary epistatic effects which can be utilize for commercial exploitation of heterosis. This study shows clearly that specific combining ability is more important than general combining ability for predicting hybrid combinations for high mineral content in cabbage head.

Hybrid chlorosis in wheat × rye crosses

Fourteen accessions of rye when crossed to Triticum aestivum cv. C 306 (Ne1ne2ch1Ch2) yielded chlorotic F1 hybrids and six accessions involved in hybrid combination with the same tester produced normal F1 hybrid plants. Two rye accessions, namely, EC 179188 and EC 143825 when crossed to the wheat lines HD 2329 (ne1Ne2ch1Ch2) and NI 5439 (ne1ne2ch1Ch2) also produced chlorosis. The hybrids between T. macha and two rye accessions produced normal plants. Variable degrees of chlorosis were observed among different wheat × rye F1 hybrids. It is suggested that the rye accessions producing chlorosis in combination with wheat cvs. C 306, HD 2329 and NI 5439 (all Ch2-carriers) carry one of the complementary genes for chlorosis. Gene symbol Chr1 is proposed for the chlorosis gene of rye.

Effect of cytoplasm and cytoplasm-nuclear interaction on combining ability and heterosis for agronomic traits in pearl millet {Pennisetum glaucum (L) Br. R}

Cytoplasmic male sterility (CMS) is considered an efficient genetic tool in pearl millet hybrid breeding. Of the several CMS sources available in pearl millet, A1 is the only CMS widely exploited to produce commercial hybrids in India. To explore the possibility of using alternate CMS sources, we studied the cytoplasmic effects of different CMS sources on agronomic characters in pearl millet. Five CMS (A) lines representing A1, A2, A3, A4 and A5 cytoplasms, their respective maintainer (B) lines and eight restorer (R) lines were used to generate 40 Axa0×xa0R and Bxa0×xa0R experimental crosses. The experimental material was evaluated at two different locations in India. Analysis of combining ability and heterosis revealed that A4 and A5 cytoplasms had desirable effects for earliness. The A5 CMS was found to be particularly promising, as compared to other CMS sources for improving grain yield. The study also indicated that the cytoplasmic effects on general combining ability (GCA) for various agronomic characters were largely non-significant. However, cytoplasmic effects on specific combining ability and heterosis were found to be modulated by cytoplasmic-nuclear interactions and influenced by the environmental conditions. The study also demonstrated the advantage of utilizing diverse male-sterile and restorer combinations in maximizing the productivity as well as for genetic and cytoplasmic diversification of hybrids in pearl millet.

Genetic diversity analysis of elite pearl millet inbred lines using RAPD and SSR markers

Pearl millet [Pennisetum glaucum (L) R Br] is one of the widely grown cereal crops in the arid and semi-arid regions of Africa and India. We undertook a study to ascertain the genetic diversity in 21 elite inbreds (parental lines of 13 pearl millet hybrids in India) using 20 Random Amplified Polymorphic DNA (RAPD) and 21 Simple Sequence Repeat (SSR) markers. Based on Polymorphism Information Content (PIC) and unique banding profiles, 6 RAPD primers OPD12, OPA16, OPB6, OPA19, OPB5 and OPB1, and 3 SSR markers Xpsmp2208, Xpsmp2223 and Xpsmp2220, were found to be highly discriminative. The PIC values ranged from 0.28 to 0.48 for the RAPD and from 0.24 to 0.60 for the SSR markers. Cluster analysis and principal component analysis of the combined dataset of RAPD and SSR markers indicated moderate genetic divergence among the elite pearl millet germplasm, besides unraveling the genetic relationships among the male sterile lines and the restorers.

GENETIC VARIABILITY, INHERITANCE AND CORRELATION FOR MINERAL CONTENTS IN CABBAGE (BRASSICA OLERACEA VAR. CAPITATA L.)

Abstract Brassica vegetables are important sources of dietary minerals. However, information on the inheritance and correlation for content of mineral elements such as iron, zinc, copper, manganese, potassium, and calcium in cabbage, which is essential if the quality of this vegetable is to be improved through breeding, is not available. Therefore, the experiment was set up with seventy-one cabbage genotypes including cultivars, germplasm and F1 hybrids grown in field. Mineral composition of the genotypes tested differed highly significantly indicating the presence of adequate amount of variability. A high heritability (>80%) accompanied by high genetic advance as percentage of mean (>40%) for uptake and accumulation of Fe, Zn, Cu, Mn and Ca indicates the predominance of additive gene, which could be improved by hybridization followed by selection breeding approach. Nevertheless, heterosis breeding would be an imperative in increasing the K content in cabbage heads as indicated by non-additive gene action for K accumulation having high heritability (>80%) and low genetic advance as percentage of mean (<30%). Moreover, both additive and non-additive genes were responsible for individual head weight. A positive correlation for Fe, Zn and Mn contents with other minerals will help in simultaneous selection of mineral elements. Nevertheless, major yield contributing ‘head weight’ was negatively correlated with minerals content and emphasized the selection of smaller head size to maintain the higher minerals content in tissues of cabbage heads. Hence, assessing the heritability, inheritance and correlation for minerals would be useful in the developing mineral-rich and productive genotypes.

Genetic analysis of apical lethality in Triticum aestivum L.

Investigations were carried out to determine the nature and number of genes governing apical lethality (apical death) in a number of intervarietal crosses of wheat. Genetic analysis of data in segregating generations of the cross WR95/HW2041 and its reciprocal cross revealed that WR95 carries a recessive gene that leads to the death of certain individuals when combined with another recessive gene derived from HW2041. The phenomenon, which is denoted here as “apical lethality”, is controlled by two complementary recessive genes coming together from two different parents in certain F2 individuals. The gene symbols apd1 in WR95 and apd2 in HW2041 are proposed for these genes of apical lethality, respectively. Uniculms observed in the F2 generation are heterozygous (apd1apd1Apd2apd2) and, therefore, the uniculmness trait does not breed true. Of the wheat genotypes tested, the gene apd2 was found to be present in CL983, CL1019, Lok-1, HW2041, HD2329, HW2011, WH147, HW2042, HW2047, WR196, WR544, WR798 and WR936, while the remaining genotypes, including some of the exotics such as Atila, carried both Apd1 and Apd2 in the homozygous condition.