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Theses

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19894
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Subject: Plant Breeding × End date: 1989 × Start date: 1989 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Potential for drought tolerance in cowpea
    (Department of Plant Breeding, College of Agriculture, Vellayani, 1989) Magie, Mereena; KAU; Sreekumar, S G
    A research programme was carried out at the department of plant breeding, College of Agriculture, Vellayani, Trivandrum during 1988 with sixteen varieties of cowpea for studying the potential for drought tolerance. The date on twentysix characters and soil moisture percentage in different plots were collected and subjected to analysis of variance/covariance. The genetic variability and correlations were estimated for the characters contributing to drought tolerance, yield and its components. The path analysis was conducted using yield as the effect and seven components contributing to drought tolerance as causes. Analysis of variance for twentysix characters revealed that significant differences existed among varieties for all the characters except for root spread at vegetative period. The analysis of variance for soil moisture percentage showed no significant difference among experimental plots indicating uniform soil moisture status in all the plots. High genotypic coefficient of variation, moderate to high heritability and high genetic advance was shown by characters such as leaf area index at vegetative, flowering and harvest periods, number of pods per plant, hundred grain weight, and proline content. Harvest index also had moderately high heritability and genetic advance. This indicates the reliability of the above components during selection programmes for the improvement of yield. Grain yield per plot showed positive genotypic correlation with leaf area index at vegetative and flowering period, root spread at harvest period, number of pods per plant, root/shoot ratio at vegetative period, grain filling period, and plant height at maturity. Path analysis revealed that harvest index and leaf area index at vegetative period had maximum positive direct effect on yield. Based on the studies on variability, correlation and path analysis it can be concluded that a plant type. Suited to drought conditions should be early flowering with deep and wide spread root system, high root/shoot ratio and leaf area index at vegetative period, low proline content, few number of stomata, long grain filling period and medium duration resulting in the production of more number of pods per plant and high harvest index. The cowpea varieties UPC-124, DPLC-198 and DPLC-216, satisfying the above plant type can be considered as drought tolerant.
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    ThesisItemOpen Access
    Potential for drought tolerance in greengram
    (Department of Plant Breeding, College of Agriculture, Vellayani, 1989) Anitha, A R; KAU; Sreekumari, Amma J
    A research programme was carried out at the Department of Plant Breeding, College of Agriculture, Vellayani, during October to December, 1988 with an objective of evaluating the potential for drought tolerance in greengram through esimation of genetic variability, correlation of yield with component characters and the direct and indirect effects of different components on yield. Twenty varieties of greengram were evaluated under open conditions without any irrigation adopting a randomized block design replicated thrice. Data on twenty characters were recorded and subjected to analysis of varience and covariance. The genotypic and phenotypic coefficient of variation, heritability in the broad sense, genetic advance and genotypic and phenotypic correlations were estimated. Path analysis was conducted with yield per plant as the effect and seven component characters as the cause.
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    ThesisItemOpen Access
    Potential for drought tolerance in blackgram (Vigna Mungo L. Hepper)
    (Department of Plant Breeding, College of Agriculture, Vellayani, 1989) Sudha Rani, S; KAU; Ramachandran Nair, N
    An investigation was carried out in the Department of Plant Breeding, College of Agriculture, Vellayani to evaluate the drought tolerance potential of twenty genotypes of blackgram under moisture stress situation. The variability present in the population was studied and a selection index was worked out to identify desirable genotypes from undesirable ones. The varieties were evaluated for yield, yield components and other drought tolerant parameters in a field trial in Randomised Block Design with three replications. The varieties tested showed significant difference for most of the drought tolerant parameters. Genotypic coefficient of variation was maximum for free proline content of leaves and minimum for days to first flowering. Days to maturity, grain-filling period and hundred seed weight exhibited high heritability indicating lesser environmental influence on these characters. Moderate to high heritability and appreciable genetic advance was recorded by leaf area, root/shoot ratio and free proline content of leaves. The correlation study has revealed that leaf area, free proline content of leaves, root spread, number of pods per plant, number of grains per pod, hundred seed weight and grain size showed positive correlation with grain yield. Days to first flowering, days to maturity and grain-filling period were found to be negatively correlated with grain yield. A selection index based on yield, yield components and drought tolerant parameters like leaf area, grain- filling period, root/shoot ratio and free proline content of leaves was found to be relatively more efficient than direct selection for yield. Based on index values, five genotypes were found to be drought tolerant. It can be concluded from the present study that an ideal plant type in blackgram for drought prone area should have early maturity, moderate leaf area, fewer number of stomata, short to medium grain-filling period, high root length and spread and moderate number of pods having maximum grain number and size.
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    ThesisItemOpen Access
    Combining ability, gene action and heterosis in sesame
    (Department of Plant Breeding, College of Agriculture, Vellayani, 1989) Elizabeth George; KAU; Sverup John
    Evaluation of six parents and fifteen hybrids of sesame were undertaken in the uplands of Vellayani for combining ability, gene action and heterosis. The six parents were chosen from twentythree sesame verities based on their general performance, which were then crossed in all possible combinations, excluding reciprocals, to get fifteen hybrids. Eleven characters, which included yield and yield attributes were studied. Significant differences were observed among the twentyone treatments for all the characters studied, except for days to mature. Combining ability analysis was carried out based on Method 2 under Model I as suggested by Griffing (1956). The variance due to specific combining ability was significant and higher in magnitude than general combining ability variance for all the characters. It was seen that the varieties S.8 and VS.27 were the best general combiners and the cross combinations CO.1 x VS.27, VS.27 x K.1 and CO.1 x S.8 were the best specific combinations for yield and yield attributes. The important yield attributes and yield were conditioned by significant g.c.a and s.c.a variances suggesting the importance of additive and non-additive gene action in combining the inheriance of these characters. Non- additive gene action was found to be predominant for all the characters studied. Heterosis percentage was calculated over mid, better and check parental values. Positive heterosis was noticed for all the characters in general and maximum vigour was manifested for the characters capsule number per plant and seed yield. Heterosis in seed yield was reflected through heterosis in yield components. In the present study, a near perfect positive correspondence was observed between s.c.a and the extent of heterosis. The varieties S.8 and VS.27 and the cross combinations CO.1 x VS.27, VS.27 x K.1 and CO.1 x S.8 can be further exploited while framing future breeding programmes.