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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
Invitro propagation in ashoka : saraca asoca (Roxb.) de wilde.
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2011) Brindha Devi, I; KAU; Sreenivasan, E
Asoka (Saraca asoca) is an important medicinal and ornamental tropical tree currently facing the threat of extinction due to overexploitation of trees occurring in forests and other natural habitats. Unscientific and destructive extraction of bark from trees has lead to acute shortage of raw bark by ayurvedic industries. Hence, the International Union for Conservation of Nature and Natural Resources (IUCN) has listed this species under ‘globally vulnerable’ category. It is also enlisted among the 36 threatened and endangered medicinal plants of India. It is considered as the sacred tree of buddhists and Hindus. Literally the term ‘asoca’ means ‘sorrow-less’ and the tree is believed to remove the grief and unhappiness. The tree has immense medicinal properties. Its bark is considered as the primary medicinal part. Due to its acute short supply compared to its demand, various development and research activities are being prioritized to conserve, utilize and improve this species. It is mainly propagated by seeds. Due to heterozygous and cross pollinated nature of the species, it never gives a true to type progeny. Therefore the present study was undertaken to standardize the technique of in vitro propagation of Saraca asoca. Standardization of suitable explants, surface sterilization procedures and culture establishment protocol, Induction of multiple shoots and Elongation of root, hardening and planting out are the major objectives of the study. Nodal segment, Internodal segment and shoot tip were the three explants tried. Various surface sterilization procedures were tried using Chloramphenicol, ethyl alcohol, 0.1% mercuric chloride and combination of ethyl alcohol and mercuric chloride in various concentration and duration, using nodal segments as explant. Surface sterilization using 70% ethyl alcohol for 3 minutes followed by 0.1% mercuric chloride for minutes proved to be the best, which gave the maximum survival percentage of 80. The next part of the study was standardisation of suitable explants for culture establishment. Among the three explants, Nodal segments gave maximum response of 60 per cent in ½ MS medium with BAP 0.5mg/l. This was followed by shoot tips in the same medium, which gave 10 per cent response. Internodal segments did not respond in any of the media used. Standardisation of basal media for culture establishment was done using nodal segments as the explants. Three media supplemented with BA 0.5 mg.l-1 were tried viz. MS, Half strenght MS, Woody plant media. Among the three, ½ MS media was identified as the best basal medium followed by MS medium. No response was seen in WPM medium. Culture establishment as well as Shoot bud initiation was attempted in ½ MS and MS media with various growth regulator combinations. Maximum response of 60 per cent was obtained in ½ MS medium containing BAP 0.5 mg/l followed by 30 percent in the same medium containing BAP 1.5 mg/l. There were no response with 2,4-D. The response obtained was callusing in all cases. Induction of multiple shooting was tried in ½ MS medium supplemented with BAP, and Kn alone as well as combinations of BAP, IAA at various concentration. Here highest response of 30 per cent of single shoots was recorded in ½ MS media containing BAP 0.5 mg/l. Response was in the form of single shoot. The single shoots with a mean length of about 1.5mm after one week of growth was obtained. With BAP 2.0 mg/l, single shoots were produced in about 5% of cultures within 54 days. Effect of Kn in various concentration ranging from 0.5 to 2.0 mg/l was found to be low in shoot induction. The maximum length of shoot of about 1.6 cm was recorded in combination of BAP 0.5 mg/l and IAA0.5 mg/l. Various combinations of IAA and IBA at different concentrations were tried for rooting of in vitro shoots. However there was no response in any of the combinations tried.
Open Access
Variability in asoka (Saraca asoca(Roxb.) de wilde)
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2010) Vidhu Francis, Palathingal; KAU; Radhakrishnan, V V
Asoka (Saraca asoca) is a sacred tree among the Buddhists and Hindus. It is called sorrow-less tree as it removes the grief. The tree has immense medicinal properties. Its bark is mainly used for correcting uterine problems. The well-known Ayurvedic preparations of asoka bark are Asokarishtam and Asokaghrutham. Due to over exploitation of this tree for its bark, this has now become almost extinct. The International Union for Conservation of Nature and Natural Resources (IUCN) has listed this species under ‘globally vulnerable’ category. It is also enlisted among the 36 threatened and endangered medicinal plants of India. Due to its acute short supply compared to its demand, various development and research activities are being prioritized to conserve, utilize and improve this species. Therefore the present study was undertaken to assess morphological variations in existing germplasm and to study the reproductive biology of S. asoca. Collection of seeds and evaluation of seed and seedling traits, evaluation of therapeutical components and molecular characterisation of asoka were the other objectives of the study. Variability studies for morphological traits of asoka indicated that height of plant and stem girth have high correlation with bark yield as well as higher direct effect. These traits can be used for identifying better genotypes for higher bark yield. In discriminant function analysis, the selection index involving height of plant along with bark yield constituted for selection criteria among asoka genotypes. Using this selection index, accessions IC566463, IC566489, IC566488, IC566482 were selected as better accessions for higher bark yield. The 43 accessions maintained in germplasm of asoka at AICRP on M&AP were grouped into two major clusters based on morphological traits. These clusters further formed 6 clusters. Accession IC566488 grouped alone in one cluster indicated that this accession was different from all other accessions. In all the other 5 clusters, accessions from Thrissur was included. This indicated that accessions did not follow geographical distributions. Some of the accessions from Thrissur may have relationship with accessions from other districts. Reproductive biology of asoka was studied. It indicated that the reproductive traits like floral biology, anthesis, pollen morphology, its viability have variability among eight trees studied in KAU campus. Among the eight trees studied, ‘KAU8’ have better reproductive traits compared to the rest. Preliminary studies were carried out in pollination system and agents for pollination in asoka. The studies indicated that ants may be one of the pollinating agents. Seed and seedling behaviour of asoka were studied on seeds collected from 80 trees located in different districts of Kerala. Seed breadth, seed volume, height of plant and stem girth were identified as selection traits for better seedlings. Hence at seed stage, bigger sized seeds with higher seed volume will result into better seedlings. Vigorous seedlings is produced from tall seedlings with higher stem girth and in mature plants for higher bark yield, height of plant and stem girth can be selection traits. Thus the selection parameters were worked out in three stages in asoka. Based on seed and seedling selection parameters, OKL4, OKL2 from Odakkali, KKL2 from Kottakkal and TVM2 from Thiruvananthapuram were selected as better mother plants for higher bark yielding accessions. The biochemical constituents (phenol and tannin content) imparting medicinal properties were estimated among the different age groups of asoka. Both phenol and tannin contents were higher in bark compared to flower and leaves. About 50 per cent of therapeutical constituents are available in flowers and hence at non destructive level, flowers of asoka can be substituted for bark. The trees KAU8, KAU7, KAU6 and among the accessions IC566474, IC566467 and among the seedlings VKA6, VKA7, VKA8, KMK3 indicated higher phenol and tannin content compared to rest. Molecular characterisation among the selected asoka accessions representing the different districts of Kerala were studied. RAPD analysis was attempted among ten accessions selected. Dendrogram was constituted based on pooled RAPD data. The ten selected accessions were grouped into two major clusters as done in morphological grouping. In grouping at molecular level, the accession IC566488 kept apart as a single group indicating the same trend at its morphological level.The clustering pattern based on molecular characterisation did not follow geographical distribution of accessions.
Open Access
Cross compatibility analysis for production of hybrids in anthurium andreanum linden
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2010) MadhuKumar, K; KAU; Mayadevi, P
The present study, ‘Cross compatibility analysis for production of hybrids in Anthurium andreanum Linden’ was undertaken to identify suitable parents with commercial qualities and to determine the cross compatibility among the selected parents in anthurium. The present investigation was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during the period 2006-2009. The analysis of variance revealed significant variation among the 40 genotypes for the eighteen characters studied. This reveals the high genetic potential for the improvement in this crop. Variability studies indicated high phenotypic and genotypic coefficients of variation for the characters for anthocyanin content, pollen fertility, leaf size/leaf area, spathe size and spadix length. The high heritability coupled with high genetic advance values were found for characters plant height, leaf size/leaf area, internodal length, spathe size, total anthocyanin content, spadix length, inclination of candle with spathe, number of flowers per spadix, life of spadix, days to initiation of female phase, days to inter phase, duration of male phase, pollen fertility and pollen size. These characters are therefore controlled by additive gene action and amenable to genetic improvement through selection. Pollen fertility estimated using acetocarmine method indicated that most of the genotypes had low fertility values. Liver Red had the highest pollen fertility of 43.01 per cent followed by Lady Jane (36.14 per cent). Pollen emergence was low in the months from March to June, during which the average maximum and minimum temperatures were relatively high. Pollen emergence was highest during October to December months. A study of six qualitative characters such as colour of young leaf and petiole, spathe colour, spathe texture, candle colour and type of inflorescence axis also showed considerable variation among the genotypes studied. Plant height was found to have highly significant positive phenotypic and genotypic correlation with leaf size/leaf area, internodal length, total Anthocyanin content, spadix length, number of flowers per spadix and life of spadix. Number of flowers per spadix had significant positive genotypic correlation with plant height, leaf size/leaf area, internodal length, spathe size, spadix length, total anthocyanin content, life of spadix, pollen fertility and pollen size. Spadix length had significant positive genotypic correlation with plant height, leaf size/leaf area, internodal length, spathe size, number of flowers per spadix, life of spadix and pollen size. Days to initiation of female phase exhibited significant negative correlation with plant height, leaf size/leaf area, spadix length and pollen fertility. The environmental correlations were absent for almost all pairs of characters except for number of leaves/spadices per plant with spathe size. Path analysis revealed that spadix length, plant height, leaf size and life of spadix had high positive direct effect on number of flowers per spadix. Mahalanobis D2 analysis clustered the 40 genotypes into seven clusters. The maximum number of genotypes (17) were included in Cluster I, followed by cluster II (7), cluster III (5), cluster IV (5) and cluster V (4). Clusters VI and VII had one genotype each. Maximum divergence was shown between the Clusters II and VI, while the minimum divergence between clusters I and II. The intracluster distance was highest for the Cluster II. Among the 13 characters considered, life of spadix contributed maximum towards divergence followed by days to initiation of female phase. Grouping of genotypes into different clusters did not reflect the geographical origin of the varieties. Selection index analysis revealed that genotype Liver Red attained the maximum selection index value followed by PR x LR and PR x DT (1) and the minimum estimates were recorded for Rembolina, W x LJ and Corolix. The grouping of genotypes by selection indices followed almost the same pattern as their clustering pattern in the D2 analysis. Intervarietal hybridization was done to analyse the cross compatibility between 15 genotypes based on the percentage of candles bearing fruits, fruit set and seed germination. A total of 127 crosses were attempted based on the availability of receptive spadices and fresh pollen, out of which 80 were found to be successful. In almost all cross combinations the percentage of candles bearing fruits ranged from 50 to 100 per cent. Among the 15 genotypes, the maximum percentage of candles bearing berries was obtained for PR x OG (90.00 per cent) followed by AW (66.67 per cent) and PR x LR (65.00 per cent). The lowest value 5 per cent was obtained for Esmeralda and 11.11 per cent for Dragon’s Tongue. The number of fruits per candle ranged from 5 in Esmeralda x (PR x OG) to 85 in (PR x OG) x (OG x DT). The crosses LR x DT, (OG x DT) x (PR x OG), LR x FR and (PR x OG) x DT also recorded higher number of fruits per candle. The average number of fruits per candles was highest for Liver Red and lowest for Esmeralda. The percentage of fruit set was below 50 per cent for all the crosses. The lowest and highest percentage of fruit set was observed for Ceasor Violet and ‘Liver Red respectively. The berries obtained from different cross combinations took 4.5 to 7 months to mature. Most of the crosses had a high percentage of single seeded berries compared to double seeded berries except for the cross FR x LR. Among single seeded berries maximum seed size was for AW x (PR x OG). In a berry largest seed among the two seeded berries were observed for the crosses AW x (PR x OG) followed by [(PR x LR) x (PR x DT (2)]. The number of days taken for germination varied from four to nine days. The seeds obtained from most of the crosses showed germination except three crosses i.e., DT x LR, (KR x LR) x LJ and Esmeralda x (PR x OG) did not germinate at all. Percentage of germination was lowest in [PR x DT (2)] x LJ and highest in (PR x LR) x C. Seedlings of 57 out of 73 crosses that germinated survived for more than four months. The seedling survival percentage ranged from 38.46 per cent in LJ x (PR x OG) to 81.25 per cent in (KR x LR) x DT. The highest average survival was recorded by Liver Red and lowest was recorded for the genotype Lady Jane. Compatibility parameters estimated based on the performance of the fifteen genotypes as pollen parents. Highest percentage of candles bearing fruits was shown by PR x OG followed by Fla Red, Dragon’s Tongue and PR x LR. Lowest percentage were recorded for Flirt and KR x LR. Number of fruits per candle was the highest for the genotype PR x DT (2) followed by PR x OG, Dragon’s Tongue and Acropolis white. In Lady Jane, Flirt and KR x LR the number of fruits were relatively lower. Higher percentage fruit set was observed for the genotypes Dragon’s Tongue while it was lowest in Lady Jane. Percentage of seed germination was the highest for Fla Red and lowest for Lady Jane. Scoring of the compatibility reactions based on the percentage of fruiting candles, fruit set and seed germination on a scale ranging from zero to nine. After scoring the different genotypes, the crosses with highest compatibility score was for the crosses (PR x OG) x (OG x DT), (PR x LR) x C, FR x DT, AW x (PR x OG), (OG x DT) x (PR x OG), (PR x LR) x (PR x OG),PR x DT (2) x (PR x OG), (OG x DT) x LR, LJ x LR, (PR x OG) x DT, (PR x OG) x LR, (PR x OG) x (PR x LR) and (PR x LR) x FR. So these were the most compatible crosses. The performance of the variety as female parent was found to be different from its performance as male parent. The female parents PR x OG, PR x LR, Lady Jane, OG x DT and PR x DT (2) got the high varietal scores. Among male parents PR x OG, DT, OG x DT, FR and PR x LR got the high varietal scores. So PR x OG, OG x DT and PR x LR could be judged as the best male as well as female parents. Among the seedlings of the successful crosses maximum number of days for maturity of leaves was taken by the cross LJ x (PR x LR) and the least number of days was taken by C x (PR x OG). Number of leaves ranged from 4.50 in DT x FR to 6.33 in [(PR x OG) x (OG x DT)]. The leaf area was maximum for the cross LR x FR and it was minimum for LJ x (PR x OG). The colour of young leaf showed a range from brown to reddish brown to greenish brown to green. The colour of petiole also varied from brown to reddish brown to greenish brown to green.
Open Access
Genetic analysis of yield and leaf curl virus resistance in chilli (Capsicum spp.)
(Department of Plant Breeding, College of Agriculture, Vellayani, 2010) Anandhi, K; KAU; Abdul Khader, K M
Pepper fruits (Capsicum spp.) are among the most consumed vegetables as fresh green or red and dried whole or ground forms in the world for its pungency. Leaf curl virus is an important biotic stress transmitted by the vector, Bemisia tabaci. Controlling the vector can be the only way to manage the disease and results in only partial control of disease. The incidence of disease is more in summer season and makes the cultivation uneconomical. There is an immediate need to develop leaf curl resistant varieties especially for summer cultivation. Hence the present investigation was undertaken at the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 2007-2009 with the objective of estimating the combining ability, heterosis and gene action involved in the inheritance of yield and leaf curl virus resistance. Five resistant C. frutescens accessions Mangalapuram Local, Thavanur Local, Kayamkulam Local, Mavelikkara Local and Nenmara Local were crossed in L x T pattern with three high yielding susceptible varieties Jwalamukhi, Jwalasakhi and Vellayani Athulya and 15 F1s were produced and evaluated along with the parents in randomized block design. Analysis of variance revealed highly significant genotypic difference for all the characters studied. The observations recorded were plant height (cm), number of branches, number of days to first flowering, plant spread (cm), duration of flowering (fruiting span), number of fruits per plant, fruit length (cm), fruit width (cm), pedicel - fruit ratio, fruit colour at intermediate stage, green fruit yield per plant (g), average fruit weight (g), number of seeds per fruit, hundred seed weight (g), duration of crop, vector population and virus disease scoring. Higher estimates of PCV and GCV were recorded for vulnerability index and green fruit yield per plant. High heritability coupled with high genetic advance were exhibited for days to first flowering, duration of flowering, number of fruits per plant, green fruit yield per plant, number of seeds per fruit, duration of crop and vulnerability index. Combining ability analysis showed that the line Mavelikkara Local and Nenmara Local were alone good general combiners for fruit yield along with leaf curl resistance. Four hybrids viz., Mavelikkara Local x Jwalasakhi, Nenmara Local x Vellayani Athulya, Kayamkulam Local x Jwalamukhi and Thavanur Local x Jwalamukhi exhibited significant sca effect for fruit yield. Considering per se performance, standard heterosis and sca effect two hybrids Mavelikkara Local x Jwalasakhi and Nenmara Local x Vellayani Athulya were found to be superior. Generation mean analysis was carried out using six-parameter model. Six generations viz. P1, P2, F1, F2, B1, B2 were built up among the crosses Mavelikkara Local x Jwalasakhi and Nenmara Local x Vellayani Athulya. Presence of additive, dominance and epistatic interaction for all the characters indicated that hybridization or recombination-breeding programme can be followed for future breeding.
Open Access
Epidemiology and management of black rot of cauliflower in plains of kerala
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2011) Lakshmi Prasanna, S; KAU; Ravi, S
The present study “Epidemiology and management of black rot of cauliflower in plains of Kerala” was taken up at Department of Plant Pathology, College of Horticulture, Vellanikkara and Agriculture Research Station, Mannuthy during 2009-2011 with an aim to study the epidemic factors influencing the incidence, development and severity of black rot caused by Xanthomonas campestris pv. campestris in plains of Kerala and to conduct field studies on its management. The pathogen was isolated from the leaves and curds of cauliflower showing typical symptoms of the disease, on PSPA medium. The colonies of the isolate were yellow in colour, circular, slimy and smooth convex with entire margin. Studies on morphological, cultural and biochemical characters confirmed the bacteria as Xcc. Various types of viz., chlorotic lesion, V shaped lesions, vein blackening; necrosis and vascular discoloration were produced by the pathogen. The symptoms were initially localized and later became systemic and stunting of plants was noticed due to systemic infection. Progression and severity of the disease was studied by inoculating the plants at five days interval starting from 10 days after transplant (DAT) up to 60 DAT. Cauliflower plants of all age group were found to be susceptible to this disease. But, young plants were succumbing to death due to infection. As the age increased there was gradual decrease in the systemic infection. Plant mortality also decreased with the increase in age at which they got infected. Sixteen cauliflower varieties were screened for black rot disease under field conditions. The incidence, calculated as A- value (AUDPC), varied from 0.53 to 12.81. These varieties were grouped in to four categories based on the scale; 0-resistant, 0-3 moderately resistant, 3-5 moderately susceptible and >5 susceptible. Out of sixteen varieties, none was found to be resistant, eight were found to be moderately resistant, two were moderately susceptible and remaining six were susceptible. An attempt was made to formulate a score card for this disease for easy observation and which has a bearing on the yield. The actual area of infection in the leaf at 10, 25 and 40 days old plants were correlated with yield and a equation y=389.061+3.371(10 DAT)-0.986(25 DAT)-2.391(40 DAT) was obtained. Three system of score card were formulated and their relationships with the yield were re-correlated statistically and three additional equations were arrived. The equation two was comparable with the original equation and that score card can be better adopted as it showed 95 per cent similarity to the original, where scale 1 and 3 showed 77.5 and 90.1 per cent similarity respectively. An attempt was made to determine the role of weather parameters on incidence of this disease. The weather factors such as maximum temperature and sunshine hours were positively correlated prevailing to the observation on 9th day and average of 7, 8 and 9 days. Similarly average of 4, 5, 6; 5, 6, 7 and 6, 7, 8 days were positively correlated with only sunshine hours. A partial multiple regression equation is also derived for predicting the disease incidence. Such correlation studies have to be conducted for at least five years consecutively to arrive at a better prediction model. Initial in vitro evaluations were done to identify the chemicals, botanicals and bioagents to be carried to the field. Field trail showed that garlic extract 10 per cent, tetracycline 250 ppm and Pseudomonas fluorescens were best treatments against Xcc.
Open Access
Morphological and biochemical characterization of aromatic rice(Oryza Sativa L.) cultivars of Wayanad district of Kerala
(Department of Plant Breeding and Genetics, College of Horticulture,Vellanikkara, 2010) Sumalatha, T V; KAU; Elsy, C R
The present study was undertaken in the Department of Plant Breeding and Genetics and in the Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Ve!!anikkara and at RARS, Ambalavayal during 2008-2010 with an aim to characterize the aromatic rice cultivars of Wayanad district, based on morphological, nutritional and biochemical studies. Gandhakasala and Jeerakasala are two popular and traditional non-Basmati aromatic ricecultivars of Wayanaddistrict, Kerala. In Wayanad Gandhakasala is cultivated in an area of 327 ha, while Jeerakasala in 22 ha. Based on grain characters 10 samples of Gandhakasala and two samples of Jeerakasala were selected for characterization. Deepthi (WND.3) was used as check variety. Among morphological studies, qualitative characters like leaf bladepubescence, . panicle exsertion, spikelet awning, awn colour, lemma and palea pubescence and seed . . coat colour showed variation and hence these can be used as morphological markers to distinguish aromatic genotypes among themselves and with Deepthi. Straw coloured short and partial awns were the characteristic feature' of Jeer aka sa I a grains, while awns were absent i!1 Gandhakasala and Deepthi. Aromatic genotypes exhibited well exserted panicles and white seed coat colour whereas Deepthi showed moderately welIexserted . . panicles and red seed coat colour. Mean performance of aromatic genotypes indicated that ligule length, grain length, grain breadth, 1000 grain weight, days to 50 per cent heading, milling recovery and maturity days provided a good base for selection. Jeerakasala genotypes took more days to 50 per cent heading and to maturity than Gandhakasala genotypes and Deepthi . . In general Gandhakasala genotypes had lesser 1000 grain weight with a mean value of 13.78 gm compared to Jeerakasala (19;82 gm) and Deepthi (26.17 gm). High grain breadth and grain length would have added to high 1000 grain weight in Deepthi. In general aromatic genotypes have lesser milling recovery than Deepthi, indicating the need [or specially designed milling machines for maximum milling recovery. The genotype GT2 appeared to have higher total carbohydrate content of 81.87 per cent/while it Was Iow for JT12 (58. 40%). Jeerakasala genotypes exhibited low mean carbohydrate content of 61.06 per cent' compared to Gandhakasala( 69.56%) and Deepthi (71.73%). The three Gandhakasala genotypes GT3, GT9 and GT7 exhibited intermediate proteincontent, indicating their nutritional superiority. The amylose content of aromatic genotypes ranged between 17.87(GT4) and 23.07 (GT2) percent. Five aromatic genotypes GT1, GT2, GT8, GTlO and JT12 had intermediate amylose content. Since intermediate amylose rice is preferred in most of the rice growing regions of the world, these genotypes will have better preference in market. Most of aromatic genotypes under study were moderately aromatic, indicating their suitability for commercial cultivation. Biochemical characterization based on isozyme studies revealed the possibility of utilizing peroxidase polymorphism for identifying the aromatic rice genotypes especially Gandhakasala genotypes from other cultivars. Studies on esterase. polymorphism revealed the presence of EST-2 band only in Deepthi indicating its use as a biochemical marker to distinguish aromatic rice genotypes from Deepthi. Heritability and genetic gain studies indicated that selection of characters like length of sterile glumes, lOOO grain weight, grain length and peroxidase activity may be effective in crop improvement programme. Correlation and path studies revealed that grain yield could be improved by simultaneous selection for high seedling height, grain breadth, milling recovery and straw yield.
Open Access
Assessment and induction of variability in plumbago species for high plumbagin content
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2010) Raji Vasudevan, Namboodiri; Radhakrishnan, V V
The study entitled "Assessment and induction of variability in Plumbago species for high plumbagin content" was carried out in the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara during 2005-2009. The main objective of the study was to induce variability in Plumbago species for high plumbagin content through -in vitro mutagenesis. A detailed survey was conducted throughout Kerala and accessions of Plumbago were collected from different ecogeographical regions ranging from Western Ghats to coastal regions of Kerala. The species Plumbago rosea seemed to be mainly distributed in highlands and medium altitude especially in the midlands of Kerala. The passport data of the collected accessions were prepared and indigenous collection(IC) numbers were obtained from NBPGR, New Delhi. Twenty five accessions of Plumbago rosea and one accession of Plumbago zeylanica were catalogued. Twenty six accessions thus collected were evaluated in replicated trial for genetic variability with respect to their biometrical traits and quality. To know the causes of failure of seed set in Plumbago rosea floral biology of the two species of Plumbago was studied . .The data were subjected to statistical analysis and results interpreted. The twenty six accessions were grouped into seven clusters which showed that there is no parallelism between the geographical distribution and clustering pattern. The path coefficient analysis indicated that large sized leaves and increased dry root weight contributed maximum to plumbagin content. Based on the ranking for dry root weight and plumbagin content three accessions were subjected to in vitro mutagenesis. In vitro regeneration through direct organogenesis and indirect organogenesis was standardised in Plumbago rosea in MS medium. Nodal segments were identified as best explants showing direct regeneration. The in vitro regenerated plants from nodal cultures on cultivation produced significantly large tuberous roots with moderate plumbagin content compared to conventional rooted cuttirigs. The callus derived from leaves, regenerat~d shoots, and roots. Thus, mass multiplication of Plumbago rosea through tissue culture was standardised. In vitro mutagenesis of selected accessions of P. rosea was successfully carried out. Based on percentage of regeneration, LDso values of 20 Gy and 40 Gy were fixed for nodal cultures and callus cultures respectively. The hardened plants obtained from selected accessions through in vitro mutagenesis showed significant variation for leaf number and size. Based on these characters variants were selected and carried over for field establishment in pot culture. The tissue culture variants on field establishment showed wide variability with respect to its stature, plant type and other morphological traits. Three in vitro mutants having plant type with large leaves and short stature for high plumbagin content were identified. The plumbagin content of these in vitro mutants have to be evaluated for its commercial exploitation.
Open Access
Characterisation and systematic evaluation of genetic resources of the genus Vigna
(Department of Plant Breeding and Genetics, College of Horticulture,Vellanikkara, 2010) Latha, M; KAU; Presannakumari, K T
Vigna belonging to the family Leguminoseae is a large genus comprising of seven sub-genera and over 150 species. The two sub-genera Vigna and Ceratotropis contain the most important cultivated species. The taxonomical identification of many of these species is still confusing. The closely related wild species serve as a source of many desirable genes that can be utilised in the interspecific hybridisation programmes. This is possible only when the relationships among the different Vigna species are well understood. In this context, the present study “Characterisation and systematic evaluation of genetic resources of the genus Vigna” was undertaken in the Department of Plant Breeding and Genetics, College of Horticulture at Vellanikkara. Investigations were undertaken to characterise the accessions of Vigna germplasm available at National Bureau of Plant Genetic Resources (NBPGR) Regional Station, Vellanikkara, Thrissur using morphological markers and to confirm the results using biochemical and molecular markers in distinct variants belonging to different taxa as well as to prepare a key for the identification of different Vigna taxa. The 150 accessions available at NBPGR Regional Station, Vellanikkara were subjected to morphological, biochemical and molecular characterisation. For morphological characterisation 48 qualitative and 24 quantitative characters were taken. The biochemical characterisation of the selected distinct variants from each taxa was done by isozymes, peroxidase and poly-phenol oxidase. The molecular characterisation was done with Inter Sequence Repeat Analysis using 10 different primers. The clustering patterns based on all three characterisation were compared and key for identification of different taxa of Vigna was developed. Among the qualitative characters evaluated, type of seed germination, nature of attachment of primary leaves, size of stipule, shape of stipule, presence of ligule, shape of bracteole, nature of pod attachment to peduncle, curvature of pod, shape of seed and shape of hilum were distinct for each taxa. Variability was observed in size and shape of stipules and bracteoles. Based on the qualitative characters the 150 accessions were reclassified into 22 taxa. One accession originally classified as V.radiata var.sublobata was found to be distinct taxa of Vigna and hence regrouped as distinct taxa. All the 24 quantitative characters studied exhibited wide range of variability. The keel pocket was present in all taxa except V.unguiculata, V.marina and V.pilosa. The length of keel pocket also varied from taxa to taxa. Cluster analysis based on qualitative, quantitative, biochemical and molecular characters resulted in 10, 5, 4 and 12 clusters respectively. A statistical methodology was worked out to compare the parallelism among the different clustering patterns. The result showed that there existed a similarity between clusters formed based on quantitative and qualitative characters, with majority of accessions of each taxa in a qualitative cluster falling in the same quantitative cluster. The accessions taken for isozyme and molecular study were distinct. Accessions of same taxa which fell in same clusters based on isozyme and molecular markers fell in different clusters based on quantitative characters and vice-versa, indicating the differences and similarities among these accessions at isozyme and molecular level. Key quantitative characters were also identified for each taxa based on weighted average. Based on morphological, biochemical and molecular characters, a dichotomous key was developed to identify different taxa. The key that is now proposed is different from the existing one which is based on floral and fruit characters alone.

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