The Genetic Stability in the Plant

The plant breeder is interested in introducing genotypes with good performance under different environmental conditions. The response of these structures to changes in the environment and the consequent instability in their traits when grown in different environments is to determine the superior ones and to estimate the overlap between the genotypes and the environment from the important criteria, therefore, the performance of the genotype is tested in different locations and seasons to determine the stability of the varieties.

Genetic Performance of Inbred and Hybrids of Maize Under Irrigation Interval

A field experiment was carried out using four inbred lines of maize BK112, Inb17, ZP607 and Zm6, as they were entered into half-diallel cross-breeding program in the fall season 2019, and 10 genotypes (6 crosses + 4 parents) were obtained according to the second Griffing method, the first model, in the spring season of 2020, the behavior of these inbreds and their hybrids were evaluated with three irrigation intervals with the aim of obtaining one or more distinct hybrids of pure strains derived from maize Zea mays L. under the irrigation interval and the study of hybrid vigor. The experiment was carried out in the fields of a farmer in Anbar Governorate, using the RCBD randomized complete block design (split – plot) with three replications. The irrigation interval (4, 8 and 12) days occupied the main plots, while the inbred and hybrids occupied the sub-plots. The results of the statistical analysis showed a significant effect of genotypes on the studied traits. The studied hybrids Zm6 × ZP607 were distinguished by their weight of 300 grains and the grain yield (85.83 g and 186.70 g) respectively. The plants grown under the irrigation interval 4 days outperformed the grain yield of the plant by giving it the highest yield of 156.03 g. It did not differ significantly with the 8-day irrigation interval, while the yield decreased significantly at the 12-day irrigation interval with a decrease of 120.8% and 120.5% than the 4 and 8 irrigation treatments, respectively. It was also found that the interaction was significant and reached the highest grain yield with an irrigation interval of 8 days, 224.0 g. The hybrid Zm6 × ZP607 gave the highest positive hybrid vigor for individual plant yield, which was 119.24%, 126.72% and 166.05% for the irrigation interval of 4, 8 and 12 days, respectively. Therefore, the plant breeder can use the characteristics of the yield components as selection guides with the superior hybrids in yield and the strength of the hybrid.

​Generation Mean Analysis for Seed Yield and Its Contributing Traits in the Inter-varietal Cross of Blackgram [Vigna mungo (L.) Hepper]

Background: Blackgram is being cultivated as an indispensable pulse crop and a rich source of vitamins and minerals. Though the requirement for blackgram is high, the productivity is low. The ultimate aim of any plant breeder in a crop improvement program is to increase seed yield/ productivity. With this background, the current study was focused to investigate genetic variability/effects on important yield and its contributing traits of blackgram. Methods: The research material comprised of P1, P2, F1, F2 and F3 obtained from a cross between CO 6 and LBG 17 varieties in blackgram. Observations on nine biometrical traits were recorded from all these five populations for generation mean analysis. By employing Mather and Jinks (1971) scaling test of C and D, the suitability nature of the simple additive-dominance model can be identified. Following Hayman (1958) perfect fit solution, the mean of five generations (P1, P2, F1, F2 and F3) was utilized to calculate five parameters. Result: Fitted genetic model revealed as important yield and yield contributing traits governed by dominance and epistasis in this study, it indicates the selection may be postponed to later generations with greater homozygosity.

A Central Role for Genetics in Plant Biology

This article describes my involvement in the development of genetics as an essential tool in the integrated study of plant biology. My research comes from a strong background in plant genetics based on my education as a plant breeder at Wageningen University and collaborations with plant physiologists and molecular geneticists in Wageningen and the wider scientific community. It initially involved the isolation and physiological characterization of mutants defective in biosynthesis or mode of action of plant hormones, photoreceptors and traits such as flowering time in both Arabidopsis and tomato. I also generated a genetic map of Arabidopsis. Subsequently, the exploitation of natural variation became a main area of interest, including the molecular identification of underlying genetic differences. The integration of various disciplines and the adoption of Arabidopsis as a main model species contributed strongly to the impressive progress in our knowledge of plant biology over the past 40 years.

Gene Action Studies in Cowpea Inbreds and Hybrids with Varying Levels of Heterosis

Background: Cowpea is an important pulse crop grown worldwide that fits well in a variety of cropping systems. Improvement in yield and related characters along with reduced duration are desirable traits in this crop. The study of heterosis reveals the type of gene action involved which enables the plant breeder to adopt suitable breeding methodology for its improvement. Methods: The present investigation was carried out with 10 parent partial diallel design to analyse the gene action and estimate of heterosis with respect to nine yield related traits in cowpea.Result: Highly significant variances observed for all the traits indicated that hybrids and parents were different from each other for the traits under study and that variability in the breeding materials was attributed to additive and non-additive gene effects. Perusal of the data revealed significant positive heterosis for all yield related traits and significant negative heterosis for days to 50% flowering indicating earliness. Among the twenty five crosses studied, VS9 x VS43, VS24 x VS45 and VS44 x VS47 had significant heterosis for maximum number of characters. Both gca and sca variances were significant for all the characters indicating both additive and non-additive gene actions controlling the various traits. The additive variance was much higher than dominance variance for the characters days to 50% flowering, pod length, pod breadth, pod weight, pods per plant and cluster, pod yield per plant, seeds per plant and length of harvest period suggesting the preponderance of additive gene action.

Selection of pepper genotypes for ornamentation based on ideotype

Peppers of the Capsicum annuum species are the most suitable for use in ornamentation, for having characters that confer aesthetic value, for being easy to cultivate and for good adaptability in pot. Despite the great variability that exists, in Brazil few commercial varieties are used for this purpose. It is of interest to the plant breeder, an ideotype that contains all the characteristics of interest for commercialization. The aim of the present study is to evaluate and select C. annuum genotypes, with potential for ornamentation that most closely resemble the proposed ideotype. 14 quantitative traits and seven qualitative traits were evaluated in 29 C. annuum genotypes, in a completely randomized design with five replications. The cultivar Calypso was used as an ideotype for presenting desirable characters to the ornamental pepper market. Nine genotypes were selected as the most similar to the Calypso ideotype (ideotype), with the potential to be used in future crossings between them and / or with the ideotype.

Response of Some Watermelon Accessions to a Puerto Rico Strain of Zucchini yellow mosaic virus

One of the most important members of the Potyviridae is Zucchini yellow mosaic virus (ZYMV). It affects watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] as well as other cucurbits in most parts of the world. Although several genotypes have been reported as having resistance to ZYMV, differential responses to ZYMV strains are known to occur. Using a Puerto Rico strain of ZYMV (ZYMV-PR, GenBank accession number MN422959), we tested the response of 11 genotypes [PIs from the U.S. Department of Agriculture (USDA) National Genetic Resources Program] previously reported as having resistance to this virus. In two greenhouse trials, the first three leaves of seedlings of each genotype were mechanically inoculated with ZYMV-PR. An enzyme-linked immunosorbent assay (ELISA) was done on each seedling’s fourth leaf and symptom severity was rated on the first, third, fifth, and seventh leaves. There were significant genotype × trial interactions for most variables, but some genotypes performed consistently in both trials. All seedlings of PI 537277 tested negative for ELISA (absorbance < 0.200) across both trials. PI 537277, PI 595200, PI 595201, and PI 595203 were generally among the accessions with the lowest symptom severity scores. Overall, symptom severity correlated poorly with ELISA readings. But all plants of PI 537277, and most plants of PI 595201 and PI 595203, had low ELISA readings and low severity scores. Despite having low severity scores, PI 595200 was among the genotypes with the highest ELISA readings in trial 2. For the plant breeder, the most useful genotypes are those that exhibit reduced severity as well as low ELISA. PI 537277, PI 595201, and PI 595203 met those criteria in this study. Of these three accessions, PI 595203 would be the most useful in a breeding program because it has shown resistance to the Puerto Rico, Florida, and China strains of ZYMV.