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Theses

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1983 - 19895
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Subject: Botany × End date: 1989 × Start date: 1980 ×
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Now showing 1 - 5 of 5
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    ThesisItemOpen Access
    Genetic studies in red gram (eafanui caiaixL)
    (Department of Agricultural Botany, College of Horticulture, Vellanikkara, 1988) Radhakrishnan, V V; KAU; Narayanan Namboodiri, K N
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    ThesisItemOpen Access
    Genic manipulations in sweet potato adopting induced mutations
    (Department of Agricultural Botany, College of Agriculture,Vellayani, 1989) Suma Bai D I; Krishnan Nair N
    An experiment was conducted at the Department of Agricultural Botany, College of Agriculture, Vellayani during 1987-1989 for genetic manipulations in sweet potato through gamma ray induced mutagenesis for increased variability and to isolate out genotypes having wider adaptability and better performance. Stem cuttings of 8 to 10 cm length bearing two nodes each, taken from fifteen sweet potato varieties were used for radiosensitivity analysis. Gamma irradiation was done by a 60 Co gamma cell unit installed in the Radio Tracer Laboratory of Kerala Agricultural University, Trichur. The material was subjected to exposure of 2-10 kR at intervals of 2 kR. The chosen dose rate was 0.162 MR/h. The direct effect of doses on the material was assessed on the basis of days to start sprouting, days to complete sprouting, sprouting percentage, vine length, branch and tuber number and weight of tubers per vine. The exposures above 4 kR caused lethality in the majority of the varieties and hence comparative analysis for ratiosensitivity was assessed at the 2 kR level. The gamma ray exposed population started sprouting late. The days taken for completion of sprouting were also more in all the varieties. Gamma rays, in addition, reduced the sprouting percentage. The percentage lethality varied depending on variety. The vine length and number of branches per vine also varied from variety to variety. They were found to be comparatively less in treated population. The tuber number and weight of tubers per vine were found to be significantly increased by gamma irradiation at 2 kR. Based on the above observations the fifteen varieties were classified into three, viz. low, medium and high radiation sensitive categories. Induced mutagenesis was done in continuation with the radiosensitivity analysis using three varieties, each selected from the low, medium and high radiation tolerant groups. The planting materials selected for gamma irradiation included fresh cuttings, rooted cuttings and rooted tubers which were exposed to radiation at a range of 500 – 2500 r, at 500 r intervals. The dose rate was 0.162 MR/h. The irradiated materials along with the control were planted on the subsequent day. In vM1 generation the direct effect of gamma rays was assessed based on days taken to start sprouting, days taken to complete sprouting, sprouting percentage, lethality on the 30th day of planting and at harvest, vine length, branch number per vine, fresh weight of vine, tuber number per vine, weight, length, girth and volume of tuber and tuber yield per vine. From vM1 plants 3-4 noded cuttings were taken from the basal, middle and top portions for raising vM2 generation. VM3 and vM4 generations were also raised in the same manner. In vM2, vM3 and vM4 generations the yield parameters were analysed in detail. Classification of the phenotypes and frequency analysis were also done. The salient findings of the experiment are the following: There was a delay in sprount initiation and for completion of sprouting caused by gamma ray exposure. A decrease in sprouting percentage and an increase in lethality were noticed under higher levels of exposures. Similarly a reduction in vine length and branch number per vine were found at higher exposures. The fresh weight of vine was reduced and the tuber number increased at higher exposures. There was an increase in mean tuber weight, length, girth, volume and tuber yield per vine at higher exposures. All the exposures and the different modes of treatment induced phenotypic variants both in negative and positive directions. Positive variants were in higher frequency in later generations. Irradiation of rooted cuttings was found to be more economical or beneficial compared to fresh cuttings and rooted tubers. The study enabled to isolate out two promising types, one each from S5 and Bhadrakalichuvala. These mutants outyielded the control and are being multiplied by vine cuttings for farm trials in different agroecological milieus of the State.
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    ThesisItemOpen Access
    Cytotoxic and clastogenic effects of some insecticides in allium cepa, L
    (Department of Agricultural Botany, College of Horticulture, Vellanikkara, 1983) Jayaprakash Naik, B; KAU; Vijayakumar, N K
    In the present investigation, the cytotoxic and clastogenic effects of three very commonly used insecticides, namely, aldrin, carbofuran and phorate were tested in Allium cepa, L., a test system. Four concentrations of each insecticides were used for the study. These concentrations were fixed taking into consideration of their field dose of application in insect control. The treatment periods fixed were 12, 24 and 48 hours. The mitotic index was computed from 4000 cells and indices of each division phases were also computed. The chromosome abnormalities were scored from about 100 to 150 cells of each phases in each treatments. Aldrin was found to be drastically mitodepressive compared to carbofuran and phorate. While phorate increased mitotic index in the lowest dose, carbofuran showed only marginal reduction. However, both the compounds reduced mitotic index in higher doses and the field doses. Aldrin exhibited a dose and period responsiveness, while carbofuran and phorate could not with regard to mitotic index. The study also revealed that aldrin is an effective toxicant on both genetic material and proteins. The various chromosome abnormalities noticed were stickiness, bridges, laggards, blurred chromosome borders, chromatin bridge, micronuclei, non-orientation of metaphase, precocious movement in anaphase, chromatin bodies, irregular anaphase, star metaphase, strays, beaked nuclei, break, C-metaphase and unequal nuclei in their decreasing order of occurrence. Unlike aldrin, carbofuran and phorate could not induce anomalies to a significant level in the lowest doses tried, 0.0075 and 0.02 per cent respectively. Chromosome bridge being the most frequent abnormality found in carbofuran, which was followed by stickiness and laggards. The frequency of abnormalities found in field and higher doses were more or less same. Phorate, on the other hand showed linear relationship in inducing chromotoxicities with respect to concentrations and period of treatment. The major types of abnormalities recorded were bridges, breaks and stickiness. The results showed that all the insecticides tried were capable of affecting the genetic material as well as protein, but to different degrees depending on concentrations. It can be tentatively concluded that they cannot be considered completely safe at the field dose of application on the cellular constituents of the organism. The results call for extensive testing of these chemicals in other test systems also.
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    ThesisItemOpen Access
    Genetic variability and correlation studies in cocoa
    (Department of Agricultural Botany, College of Horticulture, Vellanikkara, 1983) Gregory, Zachariah; KAU; Kumaran, K
    Investigation on the generic variability and correlation studies in cocoa were undertaken in the Department of Agricultural Botany, College of Horticulture, Vellanikkara during the period from July 1980 to August 1981 in a well established cocoa garden at Alpara in Trichur district, to elucidate information on the extent of variability and the degree of association existing among the 26 important plant, pod and bean characters, in a group of 135 cocoa tress, variety Forastero. Considerable variability was noted among all the characters of the sexually reproduced population of cocoa trees. Number of flowers per unit length on the trunk, number of pods per tree per year, weight of pod, volume of pod and wet weight of beans per pod showed maximum variability. Shell percentage and seed index manifested considerable variability among the bean characters. Phenotypic coefficient of variation (P.C.V.), genotypic coefficient of variation (G.C.V.) and heritability were estimated for 7 pod and bean characters. Both (P.C.V.) and (G.C.V.) were highest for attributes such as thickness of pod husk, number of beans per pod and weight of pod. Moderately high heritability was observed for weight of pod, thickness of pod husk and number of germinated beans. Volume of beans showed the lowest heritability. Yield from trees was found to be positively correlated with 6 of the characters studied, while number of germinated beans per pod and pod value were negatively correlated with yield. Out of the eight characters, pod value had the maximum contribution to yield. Number of pods per tree per year was found strongly associated with yield. Seed index and trunk girth also were positively and significantly correlated with yield. Phenotypic (rp) correlations among seven characters indicated that number of beans per pod was positively correlated with weight of pod. Positive correlations were also established between volume of beans and wet weight of beans per pod. Among the seven characters observed for genetypic (rg) correlations, wet weight of beans showed positive correlation with diameter of the pod and pod weight. Positive phenotypic as well as genotypic correlations were established in the case of wet weight of beans per pod with number of beans per pod and volume of beans. Number of beans per pod in turn, showed positive correlation with weight of pod at both levels. From the present studies it was evident that characters like diameter of pod, wet weight of beans per pod, number of beans per pod, number of germinated beans per pod, volume of pod, volume of bean, pod value, number of cushions on trunk, trunk girth, number of pods per tree per year and seed index have direct influence on the yield of cocoa. These traits can be considered while selecting cocoa trees for using in breeding programmes.
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    ThesisItemOpen Access
    Induced mutations in cowpea
    (Department of Agricultural Botany, College of Agriculture, Vellayani, 1989) Mini, V; KAU; Vijayagopal, P D
    Seeds of cowpea ( vigna unguiculata) cultivar kuruthola-payar were subjected to induced mutagenesis using four doses of gamma rays (10 to 40 krad) and four doses of EMS (0.5 to 2.0 per cent) and their effects in the M1 and M2 generations were studied. The germination percentage was observed to decrease prgogressively with the increase in dose of both mutagens although the reduction was more drastic with EMS. Reduction in survival percentage was observed with increase in the dose of gamma rays and EMS. The growth of shoot and root and plant height were reduced by both the mutagens, although gamma rays showed greater shoot inhibition and EMS showed greater root inhibition. The pollen fertility as well as seed fertility decreased linearly with increase in doses of both the mutagens. Chlorophyll chimeras were observed only in the 30 krad and 40 krad gamma ray treatments. Morphological variations noticed included plants with alterations in the number, size and shape of leaflets. The chlorophyll mutation frequency estimated on M2 progeny row basis showed an increase with increasing doses of gamma rays, except in the 40 krad treatment, which showed a slight decrease. In the case of EMS, maximum mutants were observed at the lowest dose. The chlorophyll mutation frequency estimated on M2 seedling basis showed dose-dependence. The frequencies of the different types of chrolophyll mutants did not show any dose-relationship. The segregation ratio of chlrophyll mutants was higher for EMS than gamma irradiation. The viable mutation frequencies did not show any definite relationship with the doses in both the mutagen treatments. The mutagenic effectiveness in inducing chlrophyll mutations was high at the lowest dose of both mutagens. On the basis of lethality, 20 krad of gamma rays was the most efficient, while on the basis of injury and sterility, 10 krad was the most efficient. With EMS, the 0.50 per cent treatment was the most effective as well as the most efficient treatment on the basis of lethality, injury and sterility. The mutagenic efficiency in inducing chlorophyll mutations was higher for gamma rays with respact to lethality and injury, while on the basis of sterility, EMS proved to be more effcient than gamma rays.