Morphological and reproductive characterization of nascent allotetraploids cross-compatible with cultivated peanut (Arachis hypogaea L.)

Peanut improvement is limited by a narrow genetic base. However, this obstacle can be circumvented by incorporating phenotypic variability from wild, diploid Arachis species through interspecific hybridizations. In this study, four allotetraploid interspecific hybrids IpaCor4x (A. ipaensis × A. correntina), IpaDur4x (A. ipaensis × A. duranensis), IpaSten4x (A. ipaensis × A. stenosperma), and ValSten4x (A. valida × A. stenosperma) were created and morphologically characterized through the following parameters: flower count, flower size, flower banner pigmentation, leaf area and weight, leaf hairiness, main stem height, internode length, percent of reproductive nodes, biomass, 100 pod weight, and 100 seed weight. For every trait, except for flower banner absorption at 380 nm, at least one or more allotetraploids differed from the cultivated peanut control. In general, these allotetraploids had a greater production of flowers during the growing season, larger flowers, larger and hairier leaves, taller main stems, longer primary laterals, longer internodes, lower percentage of reproductive nodes, heavier plant body masses, and smaller seeds and pods. This phenotypic diversity can be utilized directly in ornamental and forage breeding, while for oil and food crop breeding, this diversity will likely need to be selected against while desirable traits such as disease and insect resistance and abiotic stress tolerances derived from the wild diploid species are maintained.

Independent segregation of qualitative traits and estimation of genetic parameters and gene action for some quantitative traits in guar (Cyamopsis tetragonoloba L. Taub.)

Current study was undertaken to elucidate the inheritance qualitative traits namely, flower colour and leaf hairiness in two F2 populations comprising of 194 and 99 individuals with reference to yield and agronomic traits along with genetic parameters. The violet colour of flowers and leaf hairiness were dominant over white flower and smooth leaves, respectively. The 2-test revealed independent single gene inheritance for both the traits with joint segregation ratio of 9:3:3:1 in F2. Except for no. of pods per cluster and pods per plant, both parents (Smooth 25 and HG2-20) exhibited significant (p less then 0.05) differences for traits under investigation. A higher estimate of phenotypic coefficient of variance (PCV) than genonotypic coefficient of variance (GCV) was recorded for all the characters except test weight and clusters on branches. The heritability ranged from 24.36% (seeds per pod) to 92.32% (clusters on branches). Gene action as per skewness indicated that both duplicate and complementary interactions were playing role in the development of various traits, whereas, inheritance analysis as per kurtosis suggested that traits were oligogenic. Eventually, it can be concluded that high GCV, appearance of transgressive segregants and involvement of fewer major genes in defining the quantitative traits including yield, provided an opportunity for their genetic improvement.

Selection for Some Functional Markers for Adaptability of Helianthus argophyllus × Helianthus annuus Derived Population under Abiotic Stress Conditions

Abiotic stresses including drought are major crop production constraints. However, specific functional phenotypic markers induce resistance against these stresses. Therefore, a study was initiated to study the variability, inheritance and selection of epicuticular waxes (EW) and leaf hairiness (LH) along with low cell membrane injuries (CMI) within F2 populations derived by crossing H. annuus×H. argophyllus lines. These traits have been shown to be associated with drought tolerance of Helianthus argophyllus and thus study aims to introgress these traits in Helinathus annuus. The studied parent populations showed contrasting values of the traits. The drought susceptible line CMS-14 and CMS-20 showed lower epicuticular waxes (0.79, 0.69 mg g−1), leaf hairiness (0.75, 1.53) and higher cell membrane injury (40.90, 55.76 %) respectively while drought resistant line Argo 1802 and 1806 showed higher epicuticular waxes (2.28, 3.18), leaf hairiness (3.71, 3.80) and lower cell membrane injury (14.22, 21.54 %) respectively. The F1 hybrids had mean values of the three studied parameters i. e. epicuticular waxes (1.50 mg g−1), cell membrance injury (32.54 %) and leaf hairiness (2.74) in the range of parent lines, but some of F2 individuals extend beyond this range (Parents and F1s). The two-step selections maintained high variability especially of LH for set of F2 individuals (H. annuus CMS-20×H. argophyllus 1806). Simultaneous selection of F2 individuals with high values of LH or EW with low CMI was possible. The selected plants were further studied for narrow leaf, high fertility and silver canopy color. Selected material was promoted as the candidate of inbred line. Plant (F4) having introgressed traits (silver canopy) showed lower yield (19 %) than green leafed plants (53 %) and commercial hybrids under drought stress (63 % and 53 %). The study could help to increase the abiotic stress tolerance, minimize the yield losses under drought stress and increase functional diversity within sunflower.

Evaluation of the Genetic Variation of Cowpea Landraces (Vigna unguiculata) from Western Cameroon Using Qualitative Traits

Characterization of the genetic diversity and analysis of the genetic relationship between accessions of a crop species is a key step in breeding superior cultivars. The main objective of the hereby study was to determine the genetic variation between 30 cowpea accessions collected throughout the eight divisions of the Western Region of Cameroon using qualitative traits. Phenotypic variation of these accessions was evaluated using diversity indices and cluster analyses. A total of twenty qualitative traits were used for the study. Fifteen of them (75%) were polymorphic, displaying each at least two phenotypic classes. The monomorphic characters were growth pattern, leaf color, leaf hairiness, plant hairiness and pod hairiness, each with only one phenotypic class. Results showed a relatively significant level of genetic diversity among the studied cowpea accessions. Overall, the average of the observed and effective number of phenotypic classes per qualitative trait were Na = 2.350 and Ne = 1.828 respectively. The Nei’s genetic diversity and the Shannon weaver diversity index were He = 0.369, ranging from zero (monomorphic trait) to 0.655 (growth habit) and H’ = 0.609, ranging from zero (monomorphic trait) to 0.996 (seed crowding), respectively. The dendrogram constructed from the twenty qualitative traits revealed 05 accessions clusters with the number of accessions in each cluster varying from one to eleven. Information obtained from this study is likely be useful for future cowpea breeding program.