Browsing by Author "Lekha Rani, C"

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Characterisation and genetic improvement in rose (Rosa spp.) through mutagenesis
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2017) Brunda, S M; Lekha Rani, C
Compatibility studies in monopodial orchids
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2003) Ninitha Nath, C; Lekha Rani, C
A research programme "Compatibility studies In monopodia! orchids" was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 2001-2003 with the objective of undertaking intra and intergeneric hybridization and in vitro embryo culture in monopodial orchids. Twelve monopodial orchid genotypes comprising of six mono generic and six bigeneric hybrids were selected as parents after initial evaluation. They were evaluated adopting completely randomized design with six replications. Analysis of variance revealed significant differences for almost all the characters studied. Genotypic and phenotypic coefficients of variation were high for number of aerial roots, leaf area and width of leaf. Characters like number of aerial roots, width of leaf, leaf area and number of flowers per inflorescence had high heritability coupled with high genetic advance. Significant positive inter-correlation at genotypic and phenotypic levels was observed for length of flow'er and width of flower with number of leaves per cane, number of aerial roots, number of spikes per cane, length of inflorescence and length of scape. The 12 parental genotypes were crossed in all possible combinations (144) after preliminary studies on floral biology. A total of 116 crosses were done including 50 crosses, 54 reciprocals and 12 selfs. Incompatibility reaction was noticed at different stages ranging from flower abscission before the onset of any visible post pollination change to instances where seeds geminated but aborted in culture. A total of 58 combinations attempted succumbed to incompatibility at these different stages from pollination to deflasking. Harvestable green capsules were obtained from 58 combinations and they were inoculated in MS half strength basal medium. Percentage capsule yield ranged from 8 to 38 in the various hybrid combinations. Percentage filled seeds ranged from 18 to 76 in the various combinations. Capsules from twelve combinations did not contain seeds and seeds from ten combinations did not germinate on inoculation. Protocorms of developing seedlings from twelve combinations aborted at various stages of in vitro development. The remaining 24 cross combinations were taken through three to four subculture passages. Seedlings having 2-3 leaves and 2-4 roots were deflasked. Significant differences among the combinations were observed with respect to number of days taken for germination initiation, number of days taken for development of protocorms, chlorophyll, first leaf and first root primordia and for deflasking. Significant differences in seedling morphology were observed among the 24 hybrid combinations at deflasking with respect to all the seven vegetative characters studied.
Estimation of induced variability in chillies
(Department of agricultural botany , College of agriculture Vellayani, Trivandrum., 1985) Lekha Rani, C; Krishnan Nair, N
Genetic analysis of drought tolerance in rice (Oryza sativa L.)
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2017) Patil Krantikumar Haunsajirao; Lekha Rani, C
Genetic analysis of yield and its components in fodder teosinte (Euchlaena mexicana L. Schrad)
(Kerala Agricultural University, 2000) Suma Bai, D I; Lekha Rani, C
Ten fodder tcosintc types were evaluated in a randomized block design with three replications during Kharif 1995 at the College of Agriculture, Vellayani under AICRP on Forage Crops. Genetic analysis of fodder yield and its components revealed that plant height recorded high genotypic coefficient oi' variation, herilability and genetic advance indicating that selection based on this character will result in improving fodder yield. Highest genotypic correlation was observed between green fodder yield and dry matter yield. Leaf number per plant and plant stand recorded highest positive genotypic correlation with green fodder yield.
Genetic evaluation of F2 generation for yield and water stress tolerence in upland rice
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2018) Ivy Mary Rajan; Lekha Rani, C
Genetic improvement through induced mutation in dahlia (dahlia variabilis desf.)
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2017) Manu, R; Lekha Rani, C
Genetic variability in Chinese potato (solenostemom rotundifolius (poir) J K Morton) for yield and nematode tolerance
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2019) Ankitha, M O; Lekha Rani, C
The present study entitled “Genetic variability in Chinese potato (Solenostemon rotundifolius (Poir) J.K. Morton) for yield and nematode tolerance” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 2017-2019, with the objective to identify high yielding Chinese potato genotypes having nematode tolerance. Chinese potato is a minor tuber crop of the tropics in which heavy yield loss occurs due to root knot nematode infestation. The study comprised of two experiments. In the first experiment thirty accessions of Solenostemon rotundifolius (Poir) J.K. Morton, collected from ICAR - CTCRI Sreekariyam, local markets and farmers’ fields of major coleus growing tracts were evaluated for yield and nematode tolerance under field condition. These accessions were evaluated in Randomized Block Design (RBD) with thirty treatments and three replications during August 2018- January, 2019. Analysis of variance was conducted for all the thirteen characters studied. For all characters except for point of tuberization and susceptibility to nematode infestation, ANOVA revealed significant differences among all the genotypes evaluated. The genotype Kenichira local (T17) recorded the highest tuber yield plant-1 (295.37g) followed by CP9 (261.67g), Suphala (258.10g) and CP 8 (254.05g) which were on par whereas the lowest yield of 123.32g was recorded by Thottamkulam local (T10). Minimum days to flowering, maximum number of tubers plant-1 and maximum harvest index were observed for the genotype Kenichira local (T17). High genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were observed for tuber yield plant-1 and harvest index. Thus, selection for these characters would result in improvement of the genotype. High heritability coupled with high genetic advance was observed for number of tubers plant-1, tuber girth, tuber volume, average tuber weight, tuber yield plant-1, biological yield and harvest index. These characters, if selected for, would improve over generations. Tuber yield plant-1 was significantly and positively correlated with number of tubers plant-1, tuber girth, average weight of tubers and harvest index both at genotypic and phenotypic levels. So an improvement in these characters would enhance the tuber yield plant-1. Path coefficients were found out using tuber yield plant-1 as the dependent character and other correlated characters as independent variables. Path analysis revealed that number of tubers plant-1, average weight of tubers and days to flowering had positive direct effect on tuber yield plant-1. Mahalanobis’ D2 statistics was employed to study genetic divergence among the 30 genotypes which were grouped into ten clusters on the basis of relative magnitude of D2 values using Tocher’s method. Cluster I accommodated maximum number of genotypes and in sequence Clusters were having 7, 4, 4, 3,4, 3, 2, 1, 1 and 1genotypes respectively. The maximum inter-Cluster distance was observed between Clusters IV and VII. No close correspondence between geographical distribution and genetic divergence was observed. The second experiment was pot culture study for varietal reaction to root knot nematode. The same thirty genotypes evaluated in experiment I were raised in Completely Randomized Design with three replications during July, 2018 to September 2018. All the pots were artificially inoculated with second stage juveniles of Meloidogyne incognita obtained from pure culture, at the rate of 1000 juveniles plant-1. Nematode characteristics in both soil and root samples were studied. Maximum nematode population in soil was found in the genotype T8 (Parassala local 2). Root-knot index was calculated for each genotype based on scoring method suggested by Heald et al. (1989). According to this scoring method, the genotypes having 0-25 root knots per five gram of root was categorized as resistant. Fifteen genotypes were found to be in the category resistant. The genotype T11 (Pattambi local) showed highest mean values for number of larvae, root knot count, number of females and number of egg masses per five g root. The results of the current study showed the presence of wide range of variability in the thirty Chinese potato genotypes. Characters such as number of tubers plant-1 and average weight of tubers had positive significant correlation and direct association with tuber yield plant-1. Considering superior yield with nematode resistance, Kenichira local ranked first. It was followed by Suphala, CP8 and Edayur local. Kenichira local, CP 28 and Edayur local can be forwarded for further yield trials for variety development.
In vitro multiplication and molecular characterization of selected dendrobium hybrids
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2006) Rahana, S N; Lekha Rani, C
Intra and inter generic hybridization and molecular charatrization in monopodial orchids
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2008) Beena Thomas; Lekha Rani, C
Intra and interspecifif hybridization in dendrobium spp.
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2002) Lekha Rani, C; Mercy, S T
An investigation on "Intra and interspecific hybridization in Dendrobium spp." was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, during 1998-2001 with the objective of developing new hybrids of Dendrobium with novel, commercial cutflower qualities for the export market. Fourteen genotypes of Dendrobium comprising of nine commercial varieties, three semi- commercial varieties and two species were selected as parents after initial evaluation. The parental genotypes differed significantly with respect to all the 21 characters studied. High heritability combined with high GCV and genetic advance were observed for length of inflorescence, length of scape, number of flowers per inflorescence and number of nodes per cane. Significant positive inter-correlation in all pair-wise combinations at genotypic and 'phenotypic levels was observed between seven characters viz., number of leaves per clump, height of cane, leaf area per cane, age at first flowering, cane to flower first, vase life and length of inflorescence. The 14 parental genotypes were crossed in all possible combinations (196) after preliminary studies on floral biology, anthesis and pollination. Six combinations could not be attempted as the flowering seasons of the genotypes concerned did not synchronise. A total of 1696 2 pollinations were done covenng 190 (88 crosses + 88 reciprocals + 14 selfs) combinations. Pollinated flowers/immature capsules from 106 combinations abscised at different stages. Green capsules were harvested from 84 combinations. Capsules from three combinations did not contain seeds and seeds from five combinations did not germinate on inoculation. Protocorms/developing seedlings from seven combinations aborted at various stages of in vitro development. Seedlings from 69 combinations were deflasked and transplanted. Two combinations failed to get acclimatized. Progeny from 67 (62 crosses and five selfs) combinations were established successfully in the green house. The levels of incompatibility reactions were grouped under nine heads ranging from flower abscission before the onset of any visible post pollination change to failure of hybrid seedlings to get acclimatized to the ex vitro green house conditions. A total of 123 combinations attempted succumbed to incompatibility at these different stages. Percentage capsule yield ranged from 8 to 33 in the various hybrid combinations. Percentage filled seeds ranged from 10.79 to 75.93 and percentage seed germination ranged from 8.00 to 70.73. The basal medium MS half strength was the best for early germination and rapid in vitro development as compared to MS quarter strength and MS, KC and VW full strengths. The effects of growth hormones, organic additives, sucrose and charcoal on in vitro seed germination and seedling growth were studied and the best concentrations were identified. Transplanting into the humidity chamber under conditions of high relative humidity (85-95%) and controlled irrigation resulted in 94 per cent survival after four weeks. The best among the potting media tried 3 was broken tiles + charcoal + Soilrite (2:2:1), favouring high survival and well balanced post transplantation seedling growth. The 67 hybrid combinations differed significantly with respect to all the eight vegetative characters studied at 1.5 to 2.0 years after transplanting. A partial diallel established with 18 cross combinations revealed the gca effect of P3 to be beneficial for number of shoots per clump, as it was positive and significant. Non additive gene action was responsible for character expression, as dominance variance was higher than additive variance. Sixteen hybrid combinations flowered, recording significant differences for all the 12 floral characters studied. Economic heterosis, relative heterosis and heterobeItiosis of the hybrid combinations were studied for all vegetative and floral characters recorded. Considerable vegetative vigour, earliness and increase in the size of flowers and inflorescences were registered by the hybrid combinations. From the 16 flowering combinations, about 40 promising hybrids were identified. Based on three important criteria viz., novelty, distinctiveness and uniformity of the floral characters, 25 out of these 40 new hybrids were selected. These hybrids show the potential for development into new, indigenous commerical varieties.
Micropropagation of dendrobium hybrids
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2004) Sivamani, S; Lekha Rani, C
Standardisation of protocol for the rapid in vitro propagation of Dendrobium hybrids was attempted. The studies were carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 2002-2004. Different explants such as immature leaf segment, stem nodal segment and inflorescence axis were used. The effect of different basal media such as MS (full, half and quarter strength), VW (full strength) and KC (full strength) on these explants was studied. The effect of different levels of plant growth substances such as IAA, NAA, Kinetin and BA and different levels of CW on PLB development and plantlet growth was studied. Plant growth substance IBA along with AC was tried for in vitro rooting of microshoots. Among the various explants tried, stem nodal segment responded well showing early PLB differentiation. Since leaf segment and inflorescence axis did not respond even after 45 days of inoculation, they were abandoned and stem nodal segment explant alone was carried forward for further trials. Out of the different basal media tried with stem nodal segment explant, VW medium exhibited early culture establishment and rapid PLB development. Different levels of the hormone combination, BA and NAA tried showed that BA 2.0 mg l-1 + NAA 2.0 mg l-1 responded with the earliest plantlet development, but number of shoots produced was more in BA 8.0 mg l-1 + NAA 8.0 mg l-1. Combination of BA and IAA at different levels showed that BA 2.0 mg l-1 + IAA 4.0 mg l-1 produced plantlets in a minimum number of days. Number of shoots was maximum in BA and IAA each at 8.0 mg l-1. In the combination of KIN and NAA tried at different levels earlier plantlet development was observed in 2.0 mg l-1 each of the auxin and the cytokinin and the number of shoot produced was highest in 8.0 mg l-1 each of KIN and NAA. Among the different levels of KIN and IAA combination tried, 4.0 mg l-1 each of KIN and IAA was found to be the best for rapid plantlet development. Number of shoots produced was highest in the combination KIN 6.0 mg l-1 and IAA 2.0 mg l-1. Out of the three different levels of CW tried, CW 200 ml l-1 was observed to be the best in terms of early plantlet development and the production of more number of shoots. In vitro rooting of microshoots was the best in half strength MS medium supplemented with IBA 2.0 mg l-1. Addition of AC did not produce any significant effect on root development.
Stability analysis and molecular characterization of F1 hybrids in brinjal (Solanum melongena L.)
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2018) Kavishetti Vinay, Vishwanath; Lekha Rani, C
Stability analysis helps in assessing genotype × environment interaction in order to identify stable genotypes in large multi-environment trials. Therefore the present study entitled “Stability analysis and molecular characterization of F1 hybrids in brinjal (Solanum melongena L.)” was carried out to evaluate ten hybrids along with one check across four locations. The locations selected for trials were College of Agriculture, Vellayani and farmer’s fields at Thiruvalla, Sadanandapuram and Kayamkulam in Kerala. The trial seasons were kharif (2015- 16) and summer (2016-17). The objective was to study the performance of superior hybrids over different locations and seasons from heterotic crosses of brinjal and to confirm the hybridity using SSR markers. Randomized block design with four replications was employed. Stability and adaptability of yield and yield attributing characters of hybrids were analysed by Eberhart-Russell model (1966). Pooled analysis of variance revealed significant differences among the genotypes, environments and genotype × environment interaction for all the characters studied. The indication was that the hybrids responded differently to changes in the environment. Promising hybrids were identified on the basis of stability parameters viz., overall mean, regression coefficient (bi) and deviation from regression (S2di). In kharif season, the hybrid Wardha local × Palakurthi local was observed to be stable and widely adapted to all environments for days to first flowering, number of fruits plant-1, fruit weight, fruit length, fruit girth, calyx length, yield plant-1, yield plot-1 and plant height. The hybrid Wardha local × Swetha was identified as stable with regard to fruit weight, yield plant-1 and yield plot-1. The hybrid Wardha local × Vellayani local was identified as stable for favourable environments with regard to fruit length, yield plant-1 and yield plot-1. The hybrid Surya × Vellayani local was found stable for poor environments with regard to days to first flowering. Stability analysis for the summer season crop also revealed the hybrid Wardha local × Palakurthi local as stable across all environments with respect to days to first flowering, days to first harvest, number of fruits plant-1, fruit weight, fruit length and yield plant-1. Swetha × Vellayani local hybrid was stable across all environments with regard to days to first harvest, fruit weight, fruit length, calyx length, yield plant-1, yield plot-1 and plant height. The hybrid Surya × NBR-38 was found stable with respect to yield plant-1, yield plot-1 and plant height for favourable environments. Qualitative characters viz., total phenols, total sugars and vitamin C content and biotic stress traits viz., shoot and fruit borer infestation and bacterial wilt incidence were recorded for the eleven hybrids in kharif and summer season in all four locations. On the basis of overall mean performance of hybrids, results illustrated that the hybrid Swetha × Vellayani local recorded the highest values for total phenols and the hybrid NBR-38 × Vellayani local recorded the lowest values. Total sugar content was highest in Wardha local × Swetha and NBR-38 × Selection Pooja and lowest in Surya × NBR-38. The hybrid Neelima and Swetha × Vellayani local recorded higher quantity of vitamin C and NBR-38 × Vellayani local and NBR-38 × Selection Pooja recorded the lowest values. The hybrids Wardha local × Palakurthi local, Swetha × Vellayani local and Neelima recorded minimum infestation of shoot and fruit borer and was found resistant to bacterial wilt also. Hybrids and their parental lines were characterized using SSR markers. Among the four markers studied, three markers viz., emb01M15, eme08D09 and CSM31 were found to be polymorphic among the parental lines of respective hybrids viz., Surya × NBR-38, Surya × Vellayani local, NBR-38 × Selection Pooja, Swetha × Vellayani local, Wardha local × Swetha, Wardha local × Palakurthi local, Palakurthi local × Vellayani local and NBR-38 × Vellayani local which could be used for ensuring the genetic purity of respective parental lines and hybrids. F2 families viz., Wardha local × Palakurthi local, Wardha local × Swetha, Wardha local × Vellayani local and Swetha × Vellayani local were selected on the basis of yield performance from F1 for further evaluation. F2 populations revealed that family Wardha local × Palakurthi local and Wardha local × Vellayani local were superior in yield performance and yield attributing characters. The present investigation revealed that the hybrids Wardha local × Palakurthi local and Swetha × Vellayani local were stable and widely adapted over different locations and seasons and the hybridity was confirmed with the SSR markers, emb01M15 and eme08D09.