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Open Access
Biotic agents for the management of American serpentine leaf miner, Liriomyza trifolii(Burgess) (Diptera:Agromyzidae)
(Department of agricultural entomology, College of horticulture, Vellanikkara, 2014) Jyothi Sara, Jacob; KAU; Maicykutty P, Mathew
A study on “Biotic agents for the management of American serpentine leaf miner, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae)” was carried out at the Department of Agricultural Entomology, College of Horticulture, K.A.U., Vellanikkara during 2011-2013 with the objectives of collection and identification of indigenous natural enemies and to assess the pathogenicity of the entomopathogens to explore the feasibility of utilizing them for its management. Surveys were conducted in the vegetable fields for the collection and identification of natural enemies associated with L. trifolii in three districts, namely, Thrissur, Ernakulam and Kottayam from January to March, 2011. The surveys revealed the occurrence of nine species of hymenopteran parasitoids. The per cent parasitism varied from 10.96 to 58.99 per cent among the crops surveyed. Three species of eulophids, namely, Cirrospilus acadius Narendran, C. brevicorpus Shafee & Rizvi and Aprostocetus sp. as well as the braconid, Toxares sp. are new reports for India. Among the parasitoids, Closterocerus spp. were the dominant group followed by Chrysonotomyia sp. All parasitoids were solitary, larval endoparasitoids except Toxares sp. which was larval-pupal in nature. One species each of small ants (Formicidae) and a dipteran fly (Dolichopodidae) were observed as predators on L. trifolii. In the study, no entomopathogens were observed from L. trifolii. Considering the level of pesticide consumption in vegetable crops that undermine the potential of insect parasitoids and also that no entomopathogens could be observed during the survey, it was decided to evaluate entomopathogenic nematodes (EPNs) as biocontrol agents against L. trifolii. Isolation of EPNs from 72 soil samples from Thrissur, Ernakulam and Kottayam districts yielded four isolates of Steinernema carpocapsae. Bioefficacy studies carried out on these four isolates along with Steinernema bicornutum and Heterorhabditis indica showed that S. carpocapsae Isolate - 1 had the lowest LC 50 , LC 90 and LT values indicating their higher effectiveness against the maggots of the pest. 50 Pot culture study conducted to compare the potential of S. carpocapsae Isolate - 1 with other treatments showed that azadirachtin 1 EC at 0.005% was the most effective causing 84.51 per cent mortality to the maggots of L. trifolii. This was followed by the foliar application of H. indica at 32 infective juveniles (IJs)/ maggot which caused 18.98 per cent mortality. Application of Beauveria bassiana at 1×10 7 spores/ ml was not effective. In the field evaluation, fipronil 5 SC at 0.002% was found to be the most effective treatment for controlling L. trifolii followed by azadirachtin 1 EC at 0.005%. Compatibility of the IJs of the S. carpocapsae Isolate - 1, S. bicornutum and H. indica was studied with ten commonly used insecticides in the laboratory by direct exposure method. Chlorantraniliprole 18.5 SC at 0.005% was found to be the most compatible insecticide with S. carpocapsae isolate - 1 causing only 0.17 per cent mortality to IJs at 72 hours after treatment (HAT). Quinalphos 25 EC at 0.05% and chlorpyriphos20 EC at 0.05% were highly incompatible, causing 96.17 and 92.87 per cent mortality of the nematodes. Dimethoate 30 EC at 0.04% was the most compatible insecticide with S. bicornutum and caused only 0.60 per cent mortality at 72 HAT and was followed by azadirachtin 1 EC at 0.005% with 0.78 per cent mortality to the IJs. Quinalphos 25 EC at 0.05% caused 99.93 per cent mortality at 72 HAT. Heterorhabditis indica was compatible with all insecticides except quinalphos 25 EC at 0.05% which was moderately toxic resulting in 39.6 per cent mortality. The virulence, pathogenicity and multiplication of the survived IJs were not affected by the insecticide treatments. Parasitoids and EPNs were observed as potential candidates for the management of L. trifolii. Hence future studies on the bio-ecology and mass production of dominant parasitoids and standardization of methods to improve the efficacy of EPNs are suggested for the successful control of L. trifolii in polyhouses as well as in the field.
Open Access
Cryopreservation of chethikoduveli (Plumbago rosea L.) and assessment of genetic fidelity of regenerated plantlets using molecular markers
(Department of Plant Biotechnology, College of Agriculture, Vellayani, 2014) Anand, Vishnu Prakash; KAU
Investigations on “Cryopreservation of Chethikoduveli (Plumbago rosea L.) and assessment of genetic fidelity of regenerated plantlets using molecular markers” were carried out at the Department of Plant Biotechnology, College of Agriculture, Vellayani during 2011-2013. Plumbago rosea var. Agni plants were collected from AMPRS, Odakkali, Ernakulam and maintained at the Department of Plant Biotechnology, College of Agriculture, Vellayani as source of explant during the course of the study. The objectives of the present study was to standardise cryopreservation protocol by encapsulation dehydration technique for long term conservation of P. rosea and genetic fidelity assessment of plantlets recovered and regenerated from cryostorage using molecular markers. The project was carried out in two phases viz., in vitro regeneration and in vitro conservation by cryopreservation of P. rosea. In vitro regeneration protocol was optimised for P. rosea var. Agni. Various steps of in vitro regeneration viz., surface sterilization, axillary shoot proliferation, in vitro rooting and acclimatization and planting out has been standardised. For surface sterilizing, single nodal explants (3-4 cm long) were subjected to fungicide treatment with 0.1 per cent carbendazim 50 per cent W. P. (for 30 min) followed by aseptic sterilisation dip with absolute alcohol. Further, the explants were surface sterilised with 0.2 per cent mercuric chloride (for 5 min) which gave 100 per cent survival without any contamination. Enhanced release of axillary buds from single nodal explants, with maximum shoot proliferation (5.28 shoots/culture) was obtained in the medium, MS + BA 1.5 mg l-1 + IAA 1.0 mg l-1. The best response (10.67 roots/culture) of in vitro rooting of plantlets was obtained in the medium, MS + NAA 1.0 mg l-1. In vitro rooted plants gave a maximum survival rate of 76 per cent and 72 per cent, when planted out in potting media consisting of red soil and coir pith (3:1) and red soil and coir pith (2:1) supplemented with VAM respectively at 25 per cent shade. In cryopreservation studies, preconditioning treatment (sucrose 0.5 M for 7 days) recorded maximum shoot proliferation (2.67 shoots/culture) when nodal segments with single axillary bud were cultured on MS + BA 1.5 mg l-1 + IAA 1.0 mg l-1 medium. Among different encapsulation treatments, maximum shoot proliferation of (2.31 shoots/culture) was obtained in beads formed with sodium alginate 2.5 per cent and calcium chloride 100 mM, when cultured on the medium, MS + BA 1.5 mg l-1 + IAA 1.0 mg l-1. Pre-culture medium supplemented with sucrose 0.5 M for 3days gave maximum shoot proliferation (3.44 shoots/culture) when cultured on the medium, MS + BA 1.5 mg l-1 + IAA 1.0 mg l-1. A desiccation duration of 5 h at 18.13 per cent moisture level was found to be most effective giving 66.67 per cent survival and 62.50 per cent regeneration on thawing and culturing on the recovery medium MS + BA 1.5 mg l-1 + IAA 1.0 mg l-1. The beads when stored in liquid nitrogen for different duration and cultured on recovery medium did not show any significant variation with respect to survival per cent. RAPD markers were tried to study the genetic fidelity of the regenerated plantlets from encapsulated and cryopreserved axillary buds. Six primers were screened and RAPD banding patterns of the cryoregenerated plantlets and control plants were compared. Polymorphism was not found with any of the primers tested. RAPD profiles of cryoregenerated plantlets were identical to those of the control. The in vitro regeneration protocol optimized included surface sterilization of single node cuttings with 0.2 per cent HgCl2 for 5 min, axillary shoot proliferation in MS medium supplemented with BA 1.5 mg l-1 and IAA 1.0 mg l-1, in vitro rooting in MS medium supplemented with NAA 1.0 mg l-1 and planting out in potting medium, red soil and coir pith (3:1). The protocol for encapsulation dehydration technique of cryopreservation was standardised for the axillary buds of P. rosea with preconditioning in semi solid MS medium supplemented with sucrose 0.5 M for 7 days, encapsulation using sodium alginate 2.5 per cent and calcium chloride 100 mM followed by pre-culture in liquid MS supplemented with sucrose 0.5 M for 3 days and 5 h dehydration (MC 18.13 %), rapid freezing in LN for at least 2 h and recovery in the medium MS + BA 1.5 mg l-1 + IAA 1.0 mg l-1. The cryopreservation protocol using encapsulation-dehydration technique standardised could be utilised for long-term conservation of P. rosea.
Open Access
Management of bitter gourd mosaic by enhancing host resistance
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2015) Ashwini, K N; KAU; Vimi, Louis
Bitter gourd (Momordica charantia L.) is one of the important vegetable crops that occupy a pivotal position among fruit vegetables, particularly in south India. The fruits of this crop which have high commercial value and are being used for culinary preparations and various medicinal preparations. In spite of the economic importance of this vegetable, the research work carried out on protection of crop from viral disease is quite scanty. In many case, cent per cent mosaic incidence was recorded in the crop resulting in substantial economic loss. So the present study was focused on screening of bitter gourd accessions and management of bitter gourd mosaic by enhancing host resistance using defense inducers. The three different viruses causing mosaic in bitter gourd are cucumber mosaic virus (CMV), potyvirus and bitter gourd distortion mosaic virus (BDMV). As these viruses causes mixed infection in field, the separation of individual viruses was carried out using systemic indicator host plants. For separation of CMV and potyvirus, systemic indicator host plants used were cosmos and papaya respectively. BDMV was separated by white fly transmission. The pure cultures of viruses were maintained on the susceptible bitter gourd variety Preethi. The symptoms developed by different viruses were recorded under natural and artificial conditions were recorded CMV produced mosaic specks, yellow-green mosaic patches, leathery leaves and downward rolling of leaf margin. Symptoms of potyvirus infection were vein clearing, puckering, malformed leaf with reduced leaf size and rugosity. BDMV infection produced mosaic, puckering, leaf distortion, hairy growth on leaves and vines with reduction in leaf size and internodal length. For the screening of bitter gourd accessions against CMV and potyvirus, potassium phosphate buffer pH 7.0 was found to be the most suitable buffer. Among 22 accessions screened, three accessions viz., TCR 285, TCR 39 and TCR 53 were highly resistant to CMV; one accession Biliagala was highly resistant to potyvirus and 11 accessions viz.,TCR 285, TCR 39, TCR 493 ,TCR 416, TCR 492, TCR 494,TCR 380, TCR 202 and TCR 149, Green long and Biliagala were highly resistant to BDMV. The field experiment was undertaken with the objective of management of bitter gourd mosaic by using defense inducers. The three different defense inducers viz., salicylic acid 25 ppm, barium chloride 0.1% and Pseudomonas fluorescens 2 % were evaluated on the moderately resistant cultivar white long and susceptible variety Preethi. The mosaic symptom was recorded after 51 days of sowing in salicylic acid treated plants and after 40 days of sowing in control. A time gap of 5-10 days after spray of defense inducer was required for development of resistance in plants. The lowest disease severity was observed in cultivar White long treated with salicylic acid. The highest yield was recorded in Preethi treated with Pseudomonas fluorescens.
Open Access
Heterosis breeding in sesame (Sesamum indicum L.).
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2011) Gayathri, G; KAU; Dijee, Bastian
The study entitled ‘Heterosis breeding in sesame (Sesamum indicum L.)’ was undertaken at the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara. The objectives of the study were to collect and evaluate different genotypes of sesame for morphological traits and yield attributes, to identify useful parents producing heterotic crosses and developing hybrids in sesame. The study also intended to develop male sterile lines in sesame through interspecific hybridization with Sesamum malabaricum. Sesamum indicum and Sesamum malabaricum accessions were collected from Kerala and Tamil Nadu and evaluated for their morphological traits. Wide range of variation was noticed for characters like plant height, number of days to flowering and seed yield per plant which contributed maximum to genetic divergence. The genotypes studied were grouped into six clusters. High genotypic coefficient of variation (GCV) was recorded for number of capsules per plant, plant height, seed yield per plant and number of branches per plant. High heritability with high genetic advance as per cent of mean was recorded for number of days to flowering, plant height, number of branches per plant, number of capsules per plant and seed yield per plant. This indicates that the characters are governed by additive gene effects and selection for these traits will be effective. Association analysis revealed that seed yield per plant was correlated to plant height, number of capsules per plant and number of days to flowering. Path coefficient analysis indicated maximum positive direct effect by number of capsules per plant, capsule length, plant height and 1000 seed weight on seed yield per plant. In order to develop hybrids, fourteen parents were selected based on the per se performance of the genotypes. They were crossed in line X tester mating design. Forty eight hybrid combinations obtained were raised in the field along with the parents and evaluated for their heterosis and combining ability effects. Parental genotypes AVTS-06-5, AVTS-06-10, IVTS-06-12, KYM-1, Tilak and TMV-6 were identified as high combiners based on general combining ability (gca) effects. Two combinations viz. AVTS-06-5 X KYM-1 and IVTS-06-12 X TMV-3 had significant values of per se performance, specific combining ability (sca) effects and standard heterosis for seed yield per plant. They can be evaluated for their hybrid vigour over locations and seasons. The crosses AVTS-06-5 X TMV-3, AVTS-06-5 X TMV-6 and TCR 3279A X KYM-1 have been identified as potential cross combinations for isolation of promising segregants as the parents involved in these crosses had high significant gca effects for seed yield per plant but the hybrids recorded non significant sca effects. Interspecific hybridization between S.malabaricum and S.indicum was attempted to develop male sterile lines. Seed set was noticed in three interspecific hybrids which failed to germinate due to embryo abortion. Hence these embryos were rescued and raised in vitro to obtain the hybrids.
Open Access
Provenance evaluation of acacia mangium wild for growth and wood traits
(Department of Tree Physiology and Breeding, College of Forestry,Vellanikkara, 2015) Ringyao, Jajo; KAU; Santhoshkumar, A V
A provenance evaluation of A. mangium was conducted in 14 year old plantation at Livestock Research Station, Thiruvazhamkunnu, to understand the variation in growth and wood traits among the provenances. Ten provenances and one local seed source was used for the trial. The provenances had high survival percentage (77.44%), but did not differ significantly between provenances. Significant differences between provenances were found in tree height, while they were on par for DBH, volume, tree form and branching habit. The provenances of Kuranda, Arufi Village, Upper Aramia, Oriomo, Balimo and Binaturi were taller than the rest. Heritability of growth attributes was highest for height (63%). Morphometric traits of seeds were found to be significantly different between the provenances. Arufi Village provenance was found to be better than the other provenances for the traits. Seed weight and seed width were found to be strongly correlated with seedling height. Variation in germination energy, germination value and germination period were also significantly different between provenances. Lake Murray provenances showed the best performance in most of the parameters studied for germination. No significant differences between provenances were observed for germination capacity. Germination parameters are under moderate to high genetic control. Significant differences were noticed among the progenies of the provenances in height, while they did not differ in terms of collar girth and RGR. The provenances differed significantly in physical properties of wood, but not in mechanical properties. The provenances differed significantly for heartwood only at the base, while basic density was significantly different at all the height levels. Density was significantly and positively correlated with fiber length and slenderness, but negatively with fiber diameter and fiber wall thickness. The variations in fiber morphology between the provenances were also found to be significant. However, runkel ratio, flexibility and rigidity coefficient did not differ significantly between the provenances. Wood properties of the provenances were under strong genetic control. Based on the study, Tully-Mission Beach, Arufi Village, Kuranda, Upper Aramia, Lake Murray and Binaturi provenances can be recommended for growing under Kerala condition.
Open Access
Evaluation of physiological cost and subjective assessment of existing coconut climbing devices
(Department of Farm Power Machinery and Energy, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2015) Hameeda Bindu, Vahab; KAU; Bini, Sam
At present there are different models of coconut climbing devices available in the market. Most of the climbing devices safety and efficiency aspects are not being studied and needs to be comparatively evaluated and modified. In this study five coconut climbing devices were selected, those are Sit and climb type (TNAU model), Standing type (Chemberi model), KAU coconut palm climber (developed at KCAET), Kerasureksha (Model developed at ARS, Mannuthy) and CPCRI model coconut climbing device. Pertinent anthropometric dimensions of human subjects with reference to the dimensions and positions of the functional components of coconut climbing devices was identified and 35 different body dimensions useful for the design or redesign of coconut climbing devices were recorded by following standard anthropometric procedure. Ten subjects (five each for men and women) were selected, conforming to statistical requirements of anthropometric dimensions. The selected ten subjects were screened for normal health through medical and bio-clinical investigations which includes Electro Cardio Graph (ECG), blood pressure and bio-clinical analysis. Selected ten subjects were calibrated in the laboratory by indirect assessment of oxygen uptake. The relationship between the heart rate and oxygen consumption of the subjects was found to be linear for all the subjects. Then energy cost of operation of the selected coconut climbing devices were computed by multiplying the oxygen consumed by the subject during the trial period with the calorific value of oxygen as 20.88 kJ lit-1. Energy cost is comparatively less for KAU coconut palm climber with other models. Mean energy cost of male subjects during the operation of KAU coconut palm climber is 23.16 kJ min-1 and female shows 25.73 kJ min-1. Variation of heart rate and energy cost of both male and female for selected five models were statistically analyzed. Female subjects are significantly differed in both heart rate and energy cost on different coconut climbing devices and all the female subjects showed minimum heart rate while operating KAU coconut palm climbing device. But male subjects are shown any significant difference for both heart rate and energy cost. But they shows comparatively less heart rate for KAU coconut palm climbing device. The oxygen uptake in terms of VO2 max was minimum for KAU coconut palm climber (58.53 per cent) while it was 65.22 per cent for Sit and climb type (TNAU model) for male operators. Similarly for female subjects, minimum for KAU coconut palm climber (74.30 per cent). Sit and climb type (TNAU model) is difficult in operation compared with other devices. Major discomfort was happened in left thigh, right thigh, left foot and right foot. Based on these results it was found that KAU coconut palm climber and Kerasuraksha coconut climbing device were identified as more suitable for climbers than other climbing devices. Seating unit of Kerasuraksha coconut climbing device and pedal unit of KAU coconut palm climber were ergonomically comfortable for the climbing operator and developed a new model by incorporating the constructional behavior of both KAU coconut palm climber and Kerasuraksha coconut climbing device. Energy expenditure of new model for male is decreased by the rate of 10.8per cent when compared to Sit and climb type (TNAU model and with KAU coconut palm climber it is comparable. In the case of female subjects, Energy cost of new model was decreased by 7.8 per cent with Kerasuraksha coconut climbing device and 6.2 per cent with Sit and climb type (TNAU model) and it is comparable with KAU coconut palm climber. Mean VO2, VO2 max and work pulse of new model is 1.10, 58.16 per cent and 69.70 beats min-1 for male and for female it is 1.22, 73.45 per cent and 81.10 beats min-1 respectively. These values are comparatively less than value of other five models. The time required for climbing new model was 65.01 sec for male subjects which are less than other five selected coconut climbing devices and same trend for female also. The setting time of the new model was 65 sec while for KAU coconut palm climber it was 150 sec. Time was reduced by 56.67 per cent compare to KAU coconut palm climber
Open Access
Technology assessment of plant protection practices of economically dominant crops in homegardens
(Department Of Agricultural Extension, College Of Agriculture, Vellayani, 2015) Sujitha, P S; KAU; Seema, B
The study entitled “Technology assessment of plant protection practices of economically dominant crops in homegardens’' conducted in the Thiruvanathapuram district of Kerala state covering 100 homegardens having an area more than 25 cents were selected from five Agroecological units (AEU) viz.. Southern coastal plains, Southern central laterites, Southern high hills, Southern central foothills and Southern laterites. Twenty operational homegardens from each of the five panchayats belonging to the selected AEUs were chosen making the total sample size to 100 respondents. Delineation of economically dominant crops in homegardens, levels of adoption of selected KALJ plant protection practices, technology need assessment, constraints in adoption of plant protection practices and suggestions as perceived by the farmers were the major objectives of the study. The independent variables selected through judges rating were age, education, occupation, effective homegarden area, family size, farming experience, information source utilization, rational orientation, extension participation, knowledge, evaluative perception on sustainability of plant protection practices and economic motivation. The independent variable selected was adoption of selected KAU plant protection practices. The economically dominant crops identified were coconut, banana, tapioca, pepper, vegetables, yams and colacasia and arecanut respectively in the homegardens. The overall level of adoption of selected plant protection practices showed that majority (70%) of the respondents had medium level of adoption followed by 16% having high level and 14% low level of adoption. The adopter category curve delineated for the overall adoption showed that 45% of the respondents fell under early majority followed late majority (21%), laggards (16%), early adopters (14%), with no innovators. Differences in adopter categories were observed for different crops. Age, information source utilization and extension participation were found to have significant positive relationship with the dependent variable adoption of selected plant protection practices of KAU. In coconut, banana, tapioca and arecanut ease in operation was perceived as the most preferred plant protection criteria in homegardens. The result showed that 45% of the farmers found the preferred KAU plant protection practices to be useful however only 40% of the respondents felt it effective. Of the 17 ITK plant protection practices, four were specific to vegetables and banana each. Two were specific to plant protection of coconut and six of general practices. Major constraints identified were, plant protection chemicals not effective in their recommended dosage, followed by climatic influence on pest and incidence and non availability of plant protection chemicals. Suggested refinement in plant protection technology as perceived by the homegarden farmers were in generating of ecofriendly and organic plant protection measures that are suitable for homegardens followed by timely availability of plant protection inputs and generation of more pest and disease resistant varieties.
Open Access
Impact of heat and nutritional stress on the growth and reproductive performance of bucks
(Academy of Climate Change Education and Research, Vellanikkara, 2015) Abdul Niyas, P A; KAU; Girish Varma, G
A study was conducted to assess the combined effect of heat stress and nutritional restriction on growth and reproductive performances in Osmanabadi Bucks. Twenty four adult Osmanabadi bucks (average body weight (BW) 16.0 kg) were used in the present study. The bucks were divided into four groups viz., C (n=6; control), HS (n=6; heat stress), NS (n=6; nutritional stress) and CS (n=6; combined stress). The study was conducted for a period of 45 days. C and HS bucks had ad libitum access to their feed while NS and CS bucks were under restricted feed (30% intake of C bucks) to induce nutritional stress. The HS and CS bucks were exposed to solar radiation for six hours a day between 10:00 h to 16:00 h to induce heat stress. The data was analyzed using repeated measures analysis of variance. Both C and HS groups showed significantly higher (P<0.01) body weight and body condition scoring (BCS) as compared to restricted feeding groups (NS and CS). The allometric measurements also were significantly (P < 0.01) lower in restricted fed groups (NS and CS) as compared to ad libitum fed groups in CS bucks as compared to other groups (C and HS). Among the scrotal measurements, Scrotal circumference afternoon (SCA) and scrotal length afternoon (SLA) differed significantly (P<0.05) between the groups. The highest semen volume (P<0.01) was recorded in C group bucks as compared to other groups. The significantly (P<0.05) higher mass motility and progressive motility was recorded in C group bucks. However, both mass motility and progressive motility did not differ between the stress groups (HS, NS and CS). The highest plasma GH (P<0.01) was recorded in CS group and the lowest in rest all the groups (C, HS and NS). The highest plasma testosterone level was recorded in C group and the lowest in rest all groups (HS, NS and CS). The interaction between treatment and experimental days significantly (P<0.01) influenced body weight, BCS, allometric measurements, scrotal circumference, left testicular length and width, right testicular width, semen volume and growth hormone concentration. The higher expression of testicular Heat Shock Protein 70 (HSP70) Messenger Ribonucleic Acid(mRNA) was reported in HS goats. Testicular section showed significant changes for different stresses. The highest loss of spermatid density indicating decreased spermatogenesis was recorded in CS followed by HS and NS 109groups compared to C group. It can be concluded from this study that when nutrition is not compromised Osmanabadi bucks were able to withstand heat stress. This is evident from the non-significant difference on various growth and reproductive parameters studied between C and HS groups. Further, the study also revealed that Osmanabadi bucks possessed superior adaptive capability to combined stresses simultaneously. This is evident from the significant interaction of treatment and experimental days on majority of the parameters studied.
Open Access
Combination breeding for high protein cowpea (Vigna unguiculata L. Walp)
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2015) Sarath, P S; KAU; Jiji, Joseph
Cowpea (Vigna unguiculata L. Walp) is one of the most important legume crops grown in India. It is a versatile pulse crop owing to its nutritional value, weed smothering nature, drought tolerant characters, soil restoring properties and multi-purpose uses. Protein deficiency has been reported to be one of the main nutritional problems in the developing world. About one billion people are reported to be suffering from protein deficiency and malnutrition worldwide. Studies have revealed that protein content in cowpea grain ranges between 18 to 40 per cent depending on the genotypes. Identifying high yielding varieties of cowpea with high protein content will not only contribute to food security and alleviate poverty but could also contribute to the alleviation of protein deficiencies. Review on the earlier research pointed to poor emphasis on the genetic improvement of cowpea for improved protein content. Hence, the present study was envisaged to combine the high protein trait with high yielding genotypes. The study was grouped under three experiments, i) Evaluation of cowpea genotypes, ii) Hybridisation of the selected genotypes in line x tester design, iii) Evaluation of F1 hybrids. The experiments were conducted at College of Horticulture, Kerala Agricultural University, Vellanikkara during 2014-2015. All the crop management practices were followed as per KAU (2011). Evaluation of cowpea genotypes revealed that there was wide variability for all the traits studied except branches per plant among bushy and semi trailing types of cowpea. In trailing type, variability was observed for plant height, number of pods per plant, pod weight grain yield per plant and seed protein content. Among the twenty two genotypes evaluated, ten genotypes that exhibited a protein content of above 25 per cent were selected for hybridization programme. The selected genotypes (Vellayani Jyothika, Bhagyalakshmi, Anaswara, Kanakamony, Lola, Vyjayanthi, AV-5, PKB-3, PKB-4 and Sharika) were hybridized in line x tester (6 x 4) design. High magnitude of phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), heritability and genetic advance was observed for plant height, grain yield per plant and length of pods were observed in parents and hybrids suggesting scope for genetic improvement of these traits through selection. Seeds per pod and protein content exhibited low PCV and GCV but high heritability and low genetic gain, indicating that these traits were governed by non-additive gene action and therefore breeding method other than simple selection is required. Combining ability analysis revealed that higher magnitude of specific combining ability (SCA) variances than the general combining ability (GCA) variances for the traits like pods per plant, length of pod, test weight, grain yield per plant and seed protein content indicating preponderance of non-additive gene action in the inheritance of these traits. Higher estimates of GCA variances over SCA variances for plant height, days to flowering, days to first harvest, days to last harvest, pod-weight and seeds per pod implies the preponderance of additive gene action in controlling these traits. The hybrids were ranked based on mean value, sca effects and estimates of heterosis for the traits like days to flowering, pods per plant, seeds per pod, test weight, grain yield per plant and protein content. Four hybrids with the lowest scores were selected. Hybrids H2 (Vellayani Jyothika x PKB-3), H10 (Anaswara x PKB-3), H11(Anaswara x PKB-4) and H12 (Anaswara xSharika) were found to be the most promising. The transgressive segregants with high yield and protein content can be identified on further evaluation of the segregating population from the above hybrids

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