Dose Of Mutagen Research Articles

Effect of Gamma Irradiation and Ems on Germination and Survival of Okra (Abelmoschus esculentus L.) cv Arka Nikita

The present investigation was devised to observe different doses of chemical and physical mutagen on the germination and survival percentage of okra variety Arka Nikita. Seeds of okra variety Arka Nikita were treated with different doses of gamma rays and EMS. The experiment was laid out in Randomized Complete Block Design (RCBD) with thirteen treatments and three replications. It was clearly observed that germination and survival percentage decreased with increase in doses of gamma rays and EMS. Results revealed that among different treatments, treatment T1 (Control) recorded maximum germination (85) and survival per cent (98.82) and observed dose-dependent reduction in biological factors such as germination and survival, the LD50 values for gamma rays and EMS were 0.4% and 60 kR, respectively.

Impact of electron beam and ethyl methane sulphonate on chlorophyll mutations in rice genotypes ASD 16 and Norungan

Induced mutagenesis facilitates the creation of novel gene combinations within a plant genome, preserving its basic structure. This study investigates the impact of electron beam radiation and ethyl methane sulphonate (EMS) on chlorophyll mutations in rice genotypes, ASD 16 and Norungan. The seeds were irradiated with five different doses of electron beam and EMS during rabi 2021-22. The M1 generation was assessed for seedling survival, seedling height and spikelet fertility followed by an identification of chlorophyll mutants in the M2 generation. At specific mutagen doses, ASD 16 and Norungan exhibited the genotypic difference for chlorophyll mutants. Various chlorophyll mutations, such as albino, chlorina, xantha, striata, viridis, albomaculata, alboviridis and xanthoviridis were observed. ASD 16 was more sensitive to both mutagens, while Norungan showed a broader response. EMS proved to be a more effective in inducing mutations than the electron beam. Lower and moderate mutagen doses demonstrated higher efficiency indicating the importance of optimizing mutagenic conditions. This study illuminates the significance of chlorophyll mutants genetic makeup varietal differences. The strong and diverse response observed in Norungan underscores its suitability for mutation breeding programmes. These findings contribute to the efficient utilisation of mutagenesis in improving rice traits providing practical implications for elevating crop quality and promoting genetic diversity in rice cultivation.

Comparison of Mutations Induced by Different Doses of Fast-Neutron Irradiation in the M1 Generation of Sorghum (Sorghum bicolor).

Sorghum is an important C4 crop with various food and nonfood uses. Although improvements through hybridization and selection have been exploited, the introduction of genetic variation and the development of new genotypes in sorghum are still limited. Fast-neutron (FN) mutagenesis is a very effective method for gene functional studies and to create genetic variability. However, the full spectrum of FN-induced mutations in sorghum is poorly understood. To address this, we generated an FN-induced mutant population from the inbred line 'BTx623' and sequenced 40 M1 seedlings to evaluate the mutagenic effects of FNs on sorghum. The results show that each line had an average of 43.7 single-base substitutions (SBSs), 3.7 InDels and 35.15 structural variations (SVs). SBSs accounted for approximately 90.0% of the total number of small mutations. Among the eight treatment groups, FN irradiation at a dose of 19 Gy generated the highest number of mutations. The ratio of transition/transversion ranged from 1.77 to 2.21, and the G/C to A/T transition was the most common substitution in all mutant lines. The distributions of the identified SBSs and InDels were similar and uneven across the genome. An average of 3.63 genes were mutated in each mutant line, indicating that FN irradiation resulted in a suitable density of mutated genes, which can be advantageous for improving elite material for one specific or a few traits. These results provide a basis for the selection of the suitable dose of mutagen and new genetic resources for sorghum breeding.

Impact of Gamma Irradiation on Biochemical and Physiological Characteristics of Black Rice

Rice (Oryza sativa L.) is a fruit caryopsis, well known for its high calorific value and presence of high antioxidant phytochemicals such as flavonoids and anthocyanins. Further exposure of crops to different doses of physical mutagens is useful to give insight into development of quality traits for plant breeding. So, the objective of the present study was to analyse the effects of gamma irradiation on black rice seeds that were exposed to different radiation doses and to evaluate the irradiation effect on physiological and biochemical characteristics of plants. Variations were observed among different doses from non-enzymatic antioxidant activities that showed the increasing flavonoids, phenolics and carotenoids accumulation from low to high doses. A high dose irradiation releases, high amount of H2O2 as compare to O2- indicating the involvement of enzymatic antioxidants as a defence mechanism. An inverse relation was shown between peroxidase and catalase enzyme and concentration of Superoxide dismutase also increased with increasing doses. To know the level of stress on cellular metabolism, total proline and malon dialdehyde accumulation was estimated and both showed positive results for increasing doses. In case of measurement of photosynthetic parameters, chlorophyll concentration increased from 50 Gy to 100 Gy and decreased from 150 Gy to 200 Gy due to peroxidation of membrane. Significant effect was not observed in the concentration of soluble sugar among various doses. Thus, the present study, was useful to isolating effective dose (50Gy, 100 Gy) that may contribute towards advancement of qualitative traits for future breeding purposes.

CORRELATION COEFFICIENT AND REGRESSION ANALYSIS OF SOME ECONOMIC TRAITS IN GARDEN PEAS AFFECTED BY CHEMICAL AND PHYSICAL MUTAGENS

Garden pea (Pisum sativum L.) is one of the most vegetable legume crops grown in Egypt through the winter season. In order to develop high-yieldinggenotypes in this legume crop available genetic wealth is very essential. Therefore, genetic variability induced by mutagenic agents in plant growth traits and their contribution towards seed yield may be used as a criterion for yield improvement in garden peas. The overall objective of this study was to estimate the extent of association between plant growth traits with the doses of mutagenic agents through correlation and regression analysis. One germplasm of garden pea, as well as seven doses of mutagenic agents in addition to the control, were used in this study. The experiment was carried out in a randomized complete block design with three replications in the Agri-Farm of Genetic Department inside the campus of Mansoura University. Analysis of the correlation coefficient revealed that the amount of correlation coefficients appeared very close between plant fresh weight, chlorophyll b with the mutagenic doses. Meanwhile, plant dry weight, leaf area developed per plant andtotal chlorophyll concentration exhibited a positive correlation with mutagenic doses that induced new genotypes in garden peas. Therefore, these traits may be considered the most reliable traits that respond to mutagenic agents which can be used as indicators for new genotypes induced which related to effective improvement in the growth and yield of garden peas through mutation breeding.

Identification of Mutants in Groundnut (Arachis hypogaea L.) induced through Sodium Azide

The present investigation was carried out to determine the mutagenic effect of Sodium Azide on morphological traits of Kadiri-6, Gujarat Gold, Haritha Andhra and Kadiri Amaravati (Arachis hypogaea L.) in M2 generation. Pre-soaked seeds were treated with different concentrations w/v (0.1, 0.15, 0.20, 0.40) of sodium azide for 17 hrs at room temperature. The experiment was carried out with four doses of mutagen (sodium azide) for four different varieties along with their respective controls in the Randomized block design with three replications. The observation of growth parameters of both M1 & M2 mutants of Kadiri-6, Gujarat gold, Haritha Andhra and Kadiri Amaravati showed a significant variation in different traits such as germination percentage, survival percentage, seedling height, days to maturity, days to flowering, number of sterile plants, plant height at maturity, number of pods per plant, sound mature kernels and kernel yield per plant. Most of the traits decreased with an increase in the concentration dosage of sodium azide. The result of the study shows that sodium azide majorly affected the above-mentioned traits, it has significant influence on all the traits under study.

Comparative Analysis of Physical and Chemical Mutagenesis in Chrysanthemum cv. 'Candid': Assessing Genetic Variation and Breeding Potential.

In this study, we developed a mutagenesis protocol specifically designed for chrysanthemum cv. "Candid" in order to introduce genetic variation. By subjecting chrysanthemum shoots to different doses of physical and chemical mutagens, we successfully generated a total of 24 mutants, each with unique genetic compositions. We observed that the mortality rate was lowest when the shoots were exposed to 10 Gy gamma irradiation and 1.00% EMS. To assess the diversity and relatedness among the mutants, we employed RAPD and SSR markers. The combination of these markers allowed us to construct a dendrogram that effectively categorized the mutant population into distinct clusters based on the specific mutagen treatments. Interestingly, the mutants induced by 10 Gy gamma irradiation exhibited greater genetic diversity in terms of flower colors. On the other hand, mutants created with 1.00% EMS displayed a higher level of variation and yielded more viable mutants. To determine the optimal markers for studying genetic diversity, we analyzed the polymorphic information content (PIC) of different markers. Among the tested markers, OPA-07 (RAPD) and JH47 (SSR) showed the highest PIC values, indicating their effectiveness in capturing genetic variability within the mutant population. Conversely, the PIC values of OPD-07 and JH20 demonstrated the lowest among the markers tested. Our results revealed a percentage of polymorphism ranging from 81.81% to 100% for RAPD markers and 66.66% to 100% for SSR markers. These findings indicate that physical mutation induced by 10 Gy gamma irradiation can be clearly distinguished from chemical mutation induced by EMS at concentrations of 1% and 0.75% in chrysanthemum cv. "Candid.″ Overall, this study provides valuable insights into the genetic composition of the generated mutants and highlights their potential for enhancing chrysanthemum-breeding programs. The identified markers, particularly, OPA-07 and JH47, can serve as valuable tools for future studies aimed at exploring and exploiting the genetic diversity within the chrysanthemum population.

ОЦЕНКА ГЕНОТОКСИЧЕСКОГО ВОЗДЕЙСТВИЯ МИТОМИЦИНА С НА ПРИМЕРЕ APOE НОКАУТНЫХ МЫШЕЙ

BACKGROUND Mitomycin C (MMC) has a wide spectrum of genotoxicity, including inhibition of DNA synthesis, clastogenesis and mutagenesis. As an immediate-action clastogen requiring exclusively intracellular reductive activation, MMC initiates efficient DNA cross-linking. Most studies are aimed at studying single-stage acute effects, which are caused by high doses of mutagen. In turn, there are no or very few studies aimed at studying the chronic effects of MMC. Polychrome red blood cells have been accepted as a suitable target for the evaluation of micronuclei in both acute and cumulative injury. The in vivo micronucleus test is well established as a standard assay for assessing genotoxicity at the chromosomal level of mouse erythrocytes. THE AIM OF THE STUDY To create a chronic genotoxic effect of mitomycin C without lethal outcome in ApoE knockout mice while selecting the optimal dose of MMC. MATERIALS AND METHODS The study design included 6 groups of ApoE-/- mice, two doses of MMC with a concentration of 0.1 and 0.5 mg/kg, one-time and three-time administration. To assess genotoxicity, 1000 polychrome erythrocytes (PCEs) extracted from the bone marrow of a mousefemur were counted on each sample, and PCEs with micronuclei were identified. RESULTS This study aimed to find the optimal dose of MMC that has a clear genotoxic effect and does not lead to death in an ApoE knockout mouse model. With a single injection, PCEs with chromosomal damage were more common (more than 2 times; p < 0.05) in groups of mice with MMC administration (0.1 and 0.5 mg/kg; 0.39 % and 0.26 %, respectively) compared to the control group (0.15 %). We also found that the frequency of occurrence of PCEs with micronuclei in groups of mice with MMC dose of 0.1 and 0.5 mg/kg (0.36 % and 0.47 %, respectively) and three-time administration exceeded this indicator in mice from the control group (0.2 %). CONCLUSION The present study on the determination of the optimal dose of mitomycin C provides further evidence that 0.1 mg/kg is the threshold value for genotoxic effects caused by MMC. An increase in the frequency of micronucleated immature red blood cells in animals exposed to a mutagen is an indicator of induced structural or numerical chromosomal aberrations. Our results further suggest that careful selection of MMC dose is critical. Dose-response studies in rodents can provide useful information on mechanisms and dose selection for long-term toxicity studies.

Effect of Different Levels of EMS on Chrysanthemum (Dendranthema grandiflora L.)

Chrysanthemums are widely cultivated and have a significant market value due to their popularity as ornamental plants and their traditional medicinal uses. The global chrysanthemum market includes various segments, such as cut flowers, potted plants, and medicinal products. Therefore, the present investigation was carried out with title at the Department of Horticulture, Naini Agricultural Institute, Sam Higginbottom University of Agriculture Technology and Sciences, Prayagraj, Uttar Pradesh during the Winter-2022-23 with a view to determine the effect of different doses of EMS mutagen application on chrysanthemum variety Sunburst cushion for its growth quality and to work out the economics of various treatments. Under this experiment, overall, 7 treatment was prepared by soaking planting material in different doses of EMS mutagens prepared for five hours each, Treatments comprised of T0 (Control), T1 (0.5% EMS mutagen), T2 (0.75% EMS mutagen), T3 (1.0% EMS mutagen), T4 (1.5% EMS mutagen), T5 (1.25% EMS mutagen), and T6 (2.5% EMS mutagen). The current study found that the use of EMS mutagen at lower concentration had a significant positive impact on the survival, growth, and development of chrysanthemums. Among the treatments tested, T1 showed the most favorable results in terms of leaf width, leaf length, stem length, number of flowers per plant, early flowering. T1 was composed of 0.5% EMS mutagen.

Assessment of Bio-physiological damages and cytological aberrations in cowpea varieties treated with gamma rays and sodium azide.

The assessment of mutagen induced biological damage forms an important study in determining the mutagenic potency and genotypic sensitivity, a vital aspect in mutation breeding programs. A prior assessment of lethal dose (LD50), mutagen induced biological damage (alterations in bio-physiological traits and frequency of cytological aberrations) is a prerequisite for determining an optimum mutagen dose in a successful mutation breeding experiment. Therefore, in a multi-year project of mutation breeding, two widely cultivated varieties of cowpea viz., Gomati VU-89 and Pusa-578, were treated with gamma (γ) rays and sodium azide (SA) doses. The results reflected a proportionate increase in bio-physiological damages with the increase in mutagenic doses and caused a substantial reduction in mean seed germination and seedling height. Different cytological aberrations such as cytomixis, univalents, chromosome stickiness, precocious separation, unequal separation, bridges, laggards, disturbed polarity, dyads, triads, and polyads were observed in both varieties. All the mutagen doses induced a broader spectrum of cytological aberrations with varying frequencies.

Field assessment of yield and its contributing traits in cowpea treated with lower, intermediate, and higher doses of gamma rays and sodium azide.

Across the globe, plant breeders of different organizations are working in collaboration to bring preferred traits to crops of economic importance. Among the traits, "high yielding potential" is the most important as it is directly associated with food security and nutrition, one of the sustainable development goals. The Food and Agriculture Organization acknowledges plant breeders' role and efforts in achieving local and global food security and nutrition. Recognizing the importance of pulses and increasing pressure on food security, the United Nations General Assembly declared 2016 the "International year of Pulses" owing to their preferred traits such as climate change resilience, wide adaptability, low agriculture input, and protein- and nutrient-rich crops. Keeping all these developments in consideration, we initiated an induced mutagenesis program by treating cowpea (Vigna unguiculata L. Walp.) with different doses of gamma rays and sodium azide aiming to enhance the yielding potential of an otherwise outstanding variety viz., Gomati VU-89 and Pusa-578. We noticed a substantial increase in mean values of agronomic traits in putative mutants raised from seeds treated with lower and intermediate doses of mutagens. Statistical analysis such as correlation, path, hierarchical clustering analysis (HCA), and principal component analysis (PCA) were used to assess the difference between mutagenized and control populations. A significant and positive correlation of yield with yield-attributing traits was recorded. However, among all the yield attributing traits, seeds per pod (SPP) depicted the maximum direct impact upon yield, and therefore, working on this trait may yield better results. A widely used PCA revealed 40.46% and 33.47% of the total variation for var. Gomati VU-89 and var. Pusa-578, respectively. Cluster analysis clustered treated and control populations into separate clusters with variable cluster sizes. Cluster V in the variety Gomati VU-89 and cluster V and VI in the variety Pusa 578 comprised of putative mutants were higher yielding and hence could be recommended for selection in future breeding programs. We expect to release such mutant lines for farmer cultivation in Northern parts of India depending on the performance of such high-yielding mutant lines at multilocations.

Mutagenic effectiveness and efficiency of ethyl methane sulphonate (EMS) mutagen in linseed (Linum usitatissimum L.)

Induced mutation study was carried out to study the mutagenic effectiveness and efficiency ofthe mutagen ethyl methane sulphonate (EMS) in two genotypes of linseed, Him Alsi-2 and Kangra Local. On the basis of survivalpercentage in M1 generation under lab conditionsthe LD50 dose for both genotypes was estimated. Only three doses (one higher and one lower dose to LD50) were selected for raising M2 generation. Effects of these concentrations were studied on various morphological characteristics. Mutagen EMS was effective and efficient in producing chlorophyll and viable macromutations in M2 generation. Three types of chlorophyll mutants i.e. albina, xantha and radina were observed. Different types of alterations in seed color, seed texture, flower shape and plant type were observed. The macromutations although are not very useful for plant breeding but help in determining the effective mutagen doses and have also known to play an important role in evolution. EMS concentrations showing maximum effectiveness and efficiency in both varieties were different indicating varietal sensitivity towards EMS.

Mutation induction in aromatic Joha rice of Assam for improvement of morpho-agronomic traits through M1 to M3 generation

Purpose The popular Joha rice cultivar Kon Joha, cultivated throughout the state, was used to induce mutations. Kon Joha is short-grain aromatic rice with excellent cooking quality. The cultivar is tall and late maturing with an average yield of less than 2 tons ha−1 and is susceptible to lodging Materials and methods The investigation through M1 to M3 generation aimed at improving the morpho-agronomic traits of the popular Joha rice cultivar Kon Joha. The experiments were carried out during the Sali season (winter rice) from 2017 to 2019 at Instruction-cum-Research (ICR) Farm of Assam Agricultural University, Jorhat (Assam). Dry uniform seeds of Kon Joha were subject to irradiation with 100–400 Gy of gamma rays from a 60Co source. The M1 generation used a randomized complete block design with four replications during Sali 2017. A total of 5998 M1 plant progenies were subject to screening in the M2 during Sali 2018. The M3 included 662 morpho-agronomic variants raised in the plant rows during Sali 2019, and 66 mutants were confirmed. Results The M1 of Kon Joha registered a reduction in germination, seedling height, pollen/spikelet fertility and plant survival at 400 Gy. All the traits showed highly significant differences among the doses in the M2 generation. The shift in trait means was in both directions as influenced by the genotype and mutagen dose. The 66 mutants exhibited significant differences for all traits in the M3 generation. Fifty mutants were shorter than the parent Kon Joha. The GCV and PCV estimates were high (>20%) for grain yield, biological yield, productive tillers, filled grains, and average panicle weight. All the traits except panicle length exhibited high heritability coupled with high genetic advance, suggesting the predominance of additive gene action and the effectiveness of simple selection. Grain yield showed a significant positive correlation with plant height, panicle length, filled grains, spikelet fertility, the average panicle weight and harvest index in the mutant population. Conclusions Thus, mutation induction in Kon Joha proved useful in inducing desirable changes in plant architectural traits. The study further emphasized the short stature high yielding mutants with strong aroma for wide-scale testing in the state.

Comparative effects of caffeine and lead nitrate on the bio-physiological and yield associated traits of lentil (Lens culinaris Medik.)

Lentil belonging to the fabaceae family is a proteinaceous cool-season legume consumed across the world. However, lentil is low yielding with a narrow genetic base compared to other grain legumes such as chickpea, faba bean, and cowpea. In the present study, we intended to investigate the effect of two different mutagens viz., caffeine and lead nitrate on the bio-physiological and agronomical traits of lentil. Unlike other mutagens like ethyl methanesulphonate, sodium azide, and hydrazine hydrates very little is known about the mutagenic potency of caffeine and lead nitrate. The results revealed contrasting effects as lower doses of caffeine-induced a substantial increase in mean values of physiological and agronomical traits whereas both lower and higher doses of lead nitrate negatively impacted the agronomical traits of lentil. Among the mutagen doses, 0.1% caffeine was most efficient in inducing a substantial increase in mean values of bio-physiological and quantitative traits. The present study also revealed the successful conduct of induced mutagenesis in lentil and present a protocol that could be followed in future breeding programs aimed at increasing the yielding potential of legumes.

Assessment of Mutagenic Sensitivity and Lethal Dose of EMS in Papaya (Carica papaya L.) variety CO 7

Background: Mutagenesis is the process through which an organism’s genetic makeup is irreversibly altered. The objective of this study was to determine the optimal ethyl methanesulfonate (EMS) dosage to create desirable genetic variations in the papaya variety CO 7. Methods: The pre-soaked papaya seeds were exposed to five different concentrations of EMS (0.2%, 0.4%, 0.6%, 0.8% and 1.0%) for three hours. Non-treated seeds were used as a control. Data was recorded for germination per cent, seedling survival per cent, seedling length, girth, number of leaves, leaf length and width, petiole length and girth. Result: A declining trend in germination and growth of seedlings with the increase in EMS doses was observed. The probit curve analysis based on the seed germination percentage revealed that the LD50 value was found to be 0.55% EMS which was fixed as an optimal dose for large-scale mutagenesis experiments in papaya variety CO 7. The R2 value ranged from 0.73 to 0.99 and the growth reduction percentage (GR50) varied from 0.69 to 1.16 for different seedling traits studied. Since the optimization of mutagen dose would be expected to create desirable mutations with nominal biological damage, this study might assist further mutagenesis experiments in papaya.

Comparison of effectiveness and efficiency of electron beam over gamma rays to induce novel mutations in mungbean (Vigna radiata L. Wilczek)

Induced mutation is very useful in mungbean as it is having less natural genetic variation. The present study was conducted to induce variability through induced mutation, compare efficiency and effectiveness of gamma rays with electron beam on the basis of physiological changes in M1 generation; mutation frequency, spectrum of mutant phenotype and efficiency to produce novel mutations in M2 generation. Seeds of mungbean variety TM 96–2 were irradiated with doses of 200, 300, 400 and 500 Gy gamma rays and electron beam. On the basis of M1seedling growth, the effective mutagen dose (Growth Reduction Dose 50 i.e. GR50) was 440 Gy of gamma rays and 470 Gy of electron beam for TM-96–2. In M2 generation, electron beam treatments were found to induce greater frequency of chlorophyll mutations than gamma rays. The frequency of total mutants in electron beam (1.967) was found to be higher than gamma rays (1.343) along with mutation spectrum. The highest mutation spectrum was observed in 200 Gy dose of electron beam followed by 200 Gy gamma rays. Four novel mutants viz., four primary leaves in 400 Gy gamma rays, lanceolated leaves in 200, 300 and 500 Gy electron beam, yellow pod and yellow seed coat colour in 200 Gy treatment of electron beam were identified and isolated. Desirable mutants like early and synchronous maturity, large seed size and long root with drought tolerance were identified and isolated in different doses of both gamma rays and electron beam which were found true breeding in subsequent generations. Mutagenic efficiency of electron beam was higher in 200 and 400 Gy treatment as compared to same doses of gamma rays, while it was less than gamma rays in 300 and 500 Gy treatments. Mutagenic effectiveness was found to be highest in 200 Gy dose of electron beam which was more than twice that of the same dose of gamma rays.

Exploring the Relationship between Yield and Its Attributing Traits in the Induced (M2) and Recurrent Irradiated (RM2) Population of Finger Millet (Eleusine coracana L. Gaertn) Using Path Coefficient Analysis

Mutation breeding has evolved as an efficient tool for creating novel variability. Induced mutagenesis is the method of treating the base material only once, whereas recurrent mutagenesis involves subjecting the first generation (M1) to another dose of mutagen for creating extensive spectrum of genetic variations in the population. Path coefficient analysis in the induced and recurrent irradiated population measures the strength of relationship between yield attributing traits and grain yield, both directly and indirectly. The present investigation was undertaken during Kharif, 2019-20 at the K block, GKVK, University of Agricultural Sciences, Bangalore. The two genotypes of finger millet viz., GPU 28 and KMR 204 have undergone single and recurrent irradiation with different doses of gamma rays (300Gy, 400Gy) and EMS (0.1%) at Bhaba Atomic Research Centre, Mumbai. Observations were recorded for 9 quantitative traits viz., days to 50% flowering, plant height, productive tillers plant-1, ear head plant-1, fingers ear-1, finger length, panicle weight plant-1(g), test weight (g) and grain yield plant-1 (g). The studies on path analysis revealed that panicle weight and test weight established positive and direct effect towards grain yield in the induced population of finger millet. Similarly, in the recurrent irradiated population with gamma rays panicle weight, test weight, finger ear-1, 50% flowering, ear plant-1 and finger length showed direct positive effect for grain yield whereas in the recurrent irradiated population with EMS panicle weight followed by test weight, fingers ear-1, plant height, productive tillers plant-1, finger length and 50 % flowering exhibited direct positive effect for grain yield. Henceforth, direct selection based on grain yield and its attributing traits would benefit in developing high yielding variety in the crop improvement programme of finger millet.

Ameliorations of Gamma Radiations on Chlorophyll Spectrum and Morphological Characteristics of Peas

Aims: we aimed to investigate the chlorophyll spectrum and morphological characteristics of Pea under the influence of gamma radiations.
 Methods: The experimental material comprised three pea genotypes viz; Arkel, Kashi Nandini, and PSM-3. Mature and well-filled seeds were irradiated with 150 and 200 Gy doses of gamma rays, and six treatments with three control were laid into randomized block design at Research Farm, Krishi Vigyan Kendra during the spring of 2018-19.
 Results: The highest frequency of chlorophyll mutation was recorded in PSM-3 at 150 Gy and the lowest in Kashi Nandini at 200 Gy. The widest spectrum of chlorophyll mutation with seven different mutants was recorded in the PSM-3 at a 150 Gy dose. With an increase in the dose of gamma rays, there was a decrease in the mutation frequency in all the varieties.
 Conclusions: Gamma rays at a rate of 150 Gy were the best for increasing the mutation frequency and they can be used for the induction of desirable mutations in peas. The obtained results confirm that the high potency of the selected mutagenic doses induced a high phenotypic diversity in the treated population and the isolated distinct mutants were of great economic, as well as academic interest for future breeding on peas. The seeds derived from the control and treated populations should be advanced to further generations, to release more variability for quantitative traits which will favor better selection.

Efficiency of gamma irradiation and ethyl methane sulphonate in inducing variations in Jasminum auriculatum Vahl.

Vegetatively propagated crops like Jasminum auriculatum have a constraint in genetic variation due to a narrow genetic base that restricts the insights in any crop breeding programme. Mutation breeding is a potential tool that directs a way to create desirable variation effectively in vegetatively propagated crops. The optimum dose of mutagen is the one which produces the maximum frequency of mutation in turn the variation, with minimum killing. The aim of the present paper unveils the Lethal Dose (LD50) and the growth reduction dose (GR50) for both Gamma irradiation (GI) and Ethyl methane sulphonate (EMS) for the ecotype ‘Muthu Mullai’ of Jasminum auriculatum. These parameters of GR and EMS treated cuttings were analysed by considering the GR50 values of the mortality rate (57%, 48%), survival percentage (12.479Gy, 13.268mM), shoot length (18.59Gy, 18.28mM), root length (20.39Gy, 18.17mM), number of leaves (22.29Gy, 17.47mM), number of sprouts (22.97Gy, 16.17mM), vigour index (10.43Gy, 11.05mM), leaf length (21.61Gy, 19.90mM) and leaf width (19.2Gy, 16.17mM). The LD50 value was 12.479 Gy for GI and 13.268 mM for EMS treatment. The GR50 for different growth parameters ranged from 14.93 to 22.9 Gy for GI and 1.05 to 19.9 mM for EMS treatment. The mutagenic efficiency and effectiveness were 214.96 and 89.36 for GI and 48.66 and 33.77 for EMS treatment, respectively. These doses can be used for generating considerable variation, which can be put to use in future crop improvement programmes for Jasmine.

Changes on mutant pot chrysanthemums (Dendranthema × grandiflora Tzelev.)

Chrysanthemum (Dendranthema x grandiflora Tzvelev) is one of the most important ornamental plants in the world that has the richest mutant varieties with numerous colors. The objective of this study is to determine the effective mutagen dose (EMD50) for creating variations by gamma irradiation. It is aimed to get a mutagenesis protocol that could develop new mutants in pot chrysanthemums. To determine the EMD50, rooted cuttings of brownish-red color ‘Brandevil’ variety were irradiated by gamma radiation at 0, 10, 20, 30, 40, 50 Gray (Gy) doses. According to the shoot lengths, EMD50 was calculated as 27 Gy. The mutation frequency was calculated as 4.8%. Some changes were observed for flower numbers per plant, plant heights and widths, shapes and colors of both flowers and leaves. The color changes varied from brownish-red to yellow and orange. Two different colors appeared in the same pot at some genotypes as well as form changes of flowers. The similarity of the mutants was determined by the hierarchical cluster dendrogram involving five groups. Various colors were obtained for leaves and flowers. Remarkable mutations of the selected mutants were multiplied by tissue culture.