Cassava Mosaic Disease caused by cassava mosaic virus is one of the most devastating crop diseases affecting cassava cultivation. Bioinformatics approach was applied to search cassava ( Manihot esculenta Crantz.) miRNAs that targeted the cassava mosaic virus genome. Nucleotide sequences representing the genome of cassava mosaic virus were screened against a set of mature cassava miRNAs. Efficacy of cassava miRNAs against putative viral mRNA targets was analysed based on complementarity of miRNA-mRNA target pairing. This study revealed 14 cassava miRNA families to have putative targets in the cassava mosaic virus with nearly perfect complementarity. These miRNAs when artificially designed may have the potential to confer effective resistance against cassava mosaic disease infection in transformed cassava
Cassava is the most widely cultivated root crop in tropics and continues to be a crop of food security. It is the major tropical tuber crop in India , cultivated in peninsular region and North eastern hill states. Once seen as the food security crop, is now becoming increasingly a multipurpose crop acting as a major raw materials for a range of industrial uses. Cassava area is declining in India and its role in food security and economic growth is diminishing gradually. However, its significance to small and marginal farmers and its growing industrial use could not be ignored and overlooked and maximum advantage of this crop need to be explored through strategic R & D efforts. The funds allocated for cassava R & D should be judiciously used to reap the maximum benefits to the farming community. Research priority setting and monitoring is an effective method to efficiently allot scarce resources. The purpose of this paper is to develop a methodology for setting research priorities for cassava and to delineate the prioritised areas of research. The study suggested to have participatory problem diagnosis, converting problems to researchable issues, using Principle Component analysis for grouping the issues and judges rating and economic assessment for priority setting. The major areas prioritised are development of Cassava Mosaic Disease resistant varieties and its management, lowering the cost of production of cassava, germplasm collection, maintenance, and evaluation of tropical tuber crops (cassava) etc.
Agro ecological unit (AEU) 3 and AEU 9 are the two major tuber crops growing regions of Kerala cultivating tuber crops like cassava, yams and aroids mostly as intercrops in coconut gardens. Nutrient status of the soils of AEU’s are determined for making proper fertilizer recommendation to avoid both under-use and over-use of nutrients thereby attaining monetary gain as well as soil health protection by avoiding excess nutrient application. In arriving at proper nutrient status of the soils of the AEU’s, determining the weighted average nutrient status of the AEU’s with respect to the mean nutrient status and area of the panchayats/blocks was found better. It can be more meaningful and realistic from the point of view of arriving at the fertilizer recommendation to crops cultivating in that AEU’s. In this paper, as a prelude to formulate customized fertilizers for elephant foot yam (EFY) under intercropping in the coconut gardens of these two AEU’s, the weighted average data on pH, EC, organic carbon (OC), available N, P, K, Ca, Mg, S, Fe, Cu, Mn, Zn and B based on the nutrient status of the soils collected from 43 and 161 panchayats and their respective areas under AEU 3 and AEU 9 were determined. The values for AEU 3 and AEU 9 respectively were 5.85 for both AEU’s (pH), 0.291 and 0.310 dSm-1 (EC), 0.945 and 1.502% (OC), 61.97 and 69.27 kg ha-1 (available P), 213.96 and 295.87 kg ha-1 (available K), 113.32 and 600.16 ppm (exchangeable Ca), 37.53 and 114.99 ppm (exchangeable Mg), 5.07 and 21.46 ppm (available S), 3.94 and 5.68 ppm (available Zn), 0.698 and 0.816 ppm (available B), 1.79 and 3.79 ppm (available Cu), 101.20 and 64.66 ppm (available Fe) and 18.82 and 37.65 ppm (available Mn). The weighted average data of the two AEU’s indicated drastic variation in the nutrient status between the two AEU’s in the case of most of the parameters. The weighted average nutrient data of the two AEU’s clearly indicated the suitability of the soils of both AEU’s for EFY cultivation especially AEU 9 as they are rich in organic carbon as well as other essential nutrients. Moreover, this data formed a basis for fixing the theoretical optimum of soil test based nutrient recommendation to derive the practical optimum based on nutrient omission and nutrient level experiments in formulating the customized fertilizers for EFY.
Tropical tuber crops also require the micronutrient B for its growth and productivity as in the case of all other crops. The very low B content in the major tropical tuber crops growing soils of Kerala could cause the manifestation of B deficiency symptoms both in vegetative parts and tubers in the case of cassava and sweet potato. The recent occurrence of symptoms akin to hollow/brown heart of potato, in yams ( Dioscorea ), necessitated to take up experiments related to B nutrition to understand the etiology of this problem. Since the manifestation was noticed in a typical laterite soil (Typic Kandi Ustult) of the farm of ICAR-CTCRI and under similar soils of the State, a rapid nutrient status appraisal was made for the five blocks of CTCRI farm for nutrients viz., available B and exchangeable Ca as there exists a synergism between these two nutrients. A sorption study too was conducted to predict the rate of application of B for soils of varying B status. A total of 95 soil samples collected from these blocks taking into account the terrain and present cropping/fallow were analysed. Wide variation was seen in the available B status ranging from 0.14-0.419 ppm for block I and II, 0.172-0.419, 0.172- 0.848, 0.150-1.052 ppm for block III, IV and V respectively with mean values as 0.317, 0.242, 0.289, 0.331 and 0.356 ppm respectively. The mean exchangeable Ca content of the soils of these blocks were 0.896, 1.015, 0.640, 0.989, 0.877 meq 100 g-1 soil with ranges as 0.565-1.303, 0.741-1.387, 0.534-0.866, 0.762-1.215 and 0.591-1.254 meq 100 g-1 soil respectively. To understand the interaction between these nutrients, the correlation worked out indicated synergism or significant positive correlation (r=0.537) only in block V. Sorption study could find a linear increase in the quantity of B extracted in the soils of varying B contents ranging from 0.1-1.0 ppm under addition of incremental rates of B from 0.25 to 4.0 ppm. The inverse prediction function method employed to predict the quantity of B to be applied to attain soil B status to either the soil critical level of B (0.5 ppm), double (1.0 ppm) and thrice (1.5 ppm) the critical levels in soils of the above B status (0.1-1.0 ppm) was found as 0.78-3.09, 1.80-7.21 and 7.4-11.33 ppm respectively. Though the low soil available B and exchangeable Ca content can be attributed as one of the reasons for the problem manifested in yams, detailed studies are needed to explore the role of abiotic factors especially moisture and heat stress in the dynamics of these nutrients at different growth stages of the crop.
Cassava ( Manihot esculenta Crantz) is an important tropical tuber crop, the tubers of which are used both for edible purpose and for industrial uses. In Tamil Nadu, more than 500 cassava based small to large scale starch and sago producing factories are generating more than 250 tonnes of solid residue called ‘thippi’ per annum. This is an environmental pollutant affecting soil and human health and was found very difficult to dispose too. At ICAR-CTCRI, the same was converted to a nutritious organic manure through different composting methods where comosting resulted in the highest nutrient increase and the C: N ratio narrowed to 8:1 from 82:1. Experiments conducted in cassava showed its suitability as a good organic manure alternative to the commonly used organic manures like farm yard manure, green manuring in situ with cowpea, vermicompost, coir pith compost and crop residue as well as can substitute for 50% of the NPK requirement as per package of practices (PoP) and secondary nutrient Mg and micronutrient Zn to a great extent. While using any organic manure, the decomposition of the same to release the nutrients (mineralization) especially during the critical growth stage of the crop or as per the nutrient requirement of the crop needs to be understood. Hence, to understand the nutrient release pattern of thippi compost, a pot study was conducted by incubating the soil mixed with thippi compost and analysed the soil samples at monthly intervals for pH, organic carbon, electrical conductivity (EC), available N, P and K, exchangeable Ca, Mg, Fe, Cu, Mn and Zn for one year. The mean data of the soil chemical properties for one year indicated the pH, EC, available N, P and K, exchangeable Ca, Mg, available S, Fe, Cu, Mn, Zn and B increased to the tune of 0.64, 0.055 dS m- 1, 99.8, 46.1, 87.2 kg ha-1, 0.73, 0.99 meq 100g-1, 15.8, 9.4, 0.18, 1.07, 3.07 and 0.19 mg kg- 1 which in turn was 13.8 , 35.4, 46, 88.3, 107.5, 68.2, 176.7, 158, 23.5, 16.4, 72.8, 56.7 and 17.9% over the initial status. Among the nine composting options, vermicomposted thippi compost had the highest nutrient release and the maximum nutrient release was found during 5 to 8th month of incubation.
A field experiment was conducted during 2015-16 at the Regional Centre of ICAR-Central Tuber Crops Research Institute, Bhubaneswar, Odisha, India, to study the effect of various weed management practices on soil quality, microbial activities, and yield performance of elephant foot yam [ Amorphophallus paeoniifolius (Dennst.) Nicolson] in an Alfisol. The results revealed that weed control ground cover resulted in lower weed biomass and greater weed control efficiency. Significantly higher corm yield was obtained with weed control ground cover treatment (37.4 t ha-1), with an increase of 335% over control, followed by four manual weedings at 30, 60, 90 and 120 days after planting (DAP) (33.7 t ha-1) and two manual weedings at 30 and 60 DAP along with post-emergence application of glyphosate at 90 DAP (32.9 t ha-1). Use of weed control ground cover resulted in higher post-harvest soil available N, P, K, Fe, Cu, Mn and Zn, microbial population (fungi, bacteria and actinomycetes) and soil enzyme (dehydrogenase, fluorescein diacetate, acid and alkaline phosphatase) activities. Two manual weedings at 30 and 60 DAP along with application of glyphosate at 90 DAP resulted in higher soil organic carbon.
Host range of Tribolium castaneum and Rhyzopertha dominica to cassava chips were compared with stored grains such as wheat, black gram and rice. Test insects (20 Nos., 1M: 1F) were reared in splintered and flour forms of host samples under laboratory conditions. The parental adults were removed after 10th day of exposure and emergence of grub was noticed. Flour forms of wheat, black gram, rice and cassava were found more suitable for the adult emergence of T. castaneum whereas R. dominica preferred whole and broken forms of selected food except cassava. The number of adult emergence of T. castaneum and R. dominica was higher in wheat flour (67.4±6.2) and whole form of black gram (164.2±4.7) respectively. In the case of T. castaneum, the number of adult emergence was 51.8±5.8 and 57.6±2.0 in flours of black gram and rice respectively, whereas it decreased to 5.4±1.5 and 5.0±1.5 in whole forms of black gram and rice respectively. In the case of R. dominica, the number of adult emergence was 147.0±6.1 and 67.0±3.5 in whole forms of wheat and rice whereas it was only 11.6±2.0 and 12.8±2.7 when reared in flour forms of wheat and rice respectively. Among all the selected forms of cassava, only the flour forms supports the adult emergence of T. castaneum and R. dominica .
Among the tropical tuber crops, elephant foot yam (EFY) ( Amorphophallus paeoniifolius (Dennst.) Nicolson) is a highly potential and ideal intercrop for the coconut gardens of Kerala. Being highly efficient biologically with good yield potential to the tune of 30-100 t ha-1, it is high nutrient demanding too. Though, there are different nutrient management approaches for the cultivation of this crop, taking into account both crop productivity as well as soil health, balanced nutrition based on soil nutrient status and crop requirement deserves special mention. In this regard, customization of nutrients specific to regions and crops can be considered as one of the key approaches. In the protocol for arriving at the grades of the customized fertilizer formulations, one component is evolving the actual optimum of all nutrients of a particular soil by conducting nutrient omission experiments for major nutrients and nutrient level experiments for secondary and micronutrients. Such experiments were conducted for elephant foot yam under intercropping in coconut gardens of the major tuber crops growing soils of Kerala viz., laterite (AEU 9) and sandy plains (AEU 3). The theoretical optimum (based on weighted average data of the soil test) was N : P : K : Mg : Zn : B : Dolomite @ 71 : 12.5 : 106.5 : 16 : 5.25 : 1.31 : 1000 (AEU 3) and 78 : 12.5 : 90 : 16 : 5.25 : 1.31 : 1000 kg ha-1 (AEU 9) respectively. The weighted average data of nutrients was 0.95 and 1.50% (organic carbon), 61.97 and 69.27 kg ha-1 (available P), 213.96 and 295.87 kg ha-1 (available K), 113.32 and 600.16 ppm (exchangeable Ca), 37.53 and 114.99 (exchangeable Mg), 5.07 and 21.46 ppm (available S), 3.94 and 5.68 ppm (available Zn), 0.70 and 0.82 ppm (available B), 1.79 and 3.79 ppm (available Cu), 101.20 and 64.66 ppm (available Fe) and 18.82 and 37.65 ppm (available Mn) respectively for AEU 3 and AEU 9. Different sub optimal and super optimal levels of the theoretical optimum of nutrients viz., N,P, K, Mg, Zn, B and Dolomite was kept as treatments for conducting these experiments in the two locations of AEU 9 and one location in AEU 3. Based on the corm yield data from these experiments, the actual optimum derived by conducting the NOP (Nutrient Omission Plot) and NLE (Nutrient Level Experiment) was N: P: K: Mg: Zn: B: Dolomite @ 140: 20: 225: 19.2: 4.2: 1.575: 1500 kg ha-1 for AEU 3 and 160:12.5:180: 19.2:6.3:1.975:1500 kg ha-1 for AEU 9 respectively and these experiments formed the basis for calculating the different nutrient use parameters for arriving at the grades of the customized fertilizer formulations.
Phenology of greater yam ( Dioscorea alata L.) was studied by planting two greater yam varieties viz., Sree Keerthi and Sree Karthika for three seasons (2013, 2014 and 2015) at ICAR-CTCRI, Thiruvananthapuram, Kerala. Sree Keerthi took 16 to 23 days for sprouting, 88 days for tuber initiation, 236 to 243 days for senescence, which lasted for 24 to 39 days. Sree Karthika took 17 to 28 days for sprouting, 83 days for tuber initiation, 236 days for senescence which lasted for 26 to 45 days. Active tuber development was noticed between 6 to 8 months of planting (180 to 240 days). Timely planting resulted in more tuber yield in Sree Keerthi (26.4 to 31.5 t ha-1) than Sree Karthika (22.65 to 29.3 t ha-1). Delayed planting although resulted in early emergence and tuber initiation, senescence was also early resulting in yield loss in both the varieties. However, Sree Keerthi resulted in less yield loss compared to Sree Karthika, indicating its suitability for delayed planting.
Sweet potato weevil (SPW), Cylas formicarius (Fab.) is the most devastating pest of sweet potato in the field and tubers under storage. The infestation of weevil reduces the quality of the tubers; therefore, it affects marketability and economic value of the crop as well. Efficacy of six insecticides, namely Imidacloprid, Chlorpyrifos, Malathion, Dimethoate, Dichlorvos and Quinalphos at three concentrations (0.001, 0.01 and 0.05%) were evaluated against SPW by two different bioassay methods foliar application and vine dippingand compared their toxicity against control with water. In the case of foliar application, the mortality of SPW on 1, 3, 5, 7 and 9 days after treatment (DAT) was highest in the treatments with Imidacloprid and Chlorpyrifos. In contrast, it was least in Malathion and Dimethoate. Imidacloprid was found most effective for vine dipping, and its effect lasted upto 9 DAT. The present study revealed that foliar application of Imidacloprid at the concentrations of 0.01 and 0.05% was most effective against SPW.
Experiments were conducted at ICAR-CTCRI during 2016 and 2017 to study the rooting pattern of elephant foot yam, variety Gajendra under drip irrigation and rainfed conditions, by growing the crop in semi permanent cement tanks and periodical uprooting. The root system, emerging from the newly developing corms, was shallow growing to a maximum depth of 30-40 cm, but spread horizontally upto 1.2 m.The pattern of rooting was more or less similar during both the seasons. Number of roots, length and root biomass increased gradually from sprouting, and reached maximum at full canopy development stage or 3 MAP. These parameters declined with corm bulking and reached minimum at crop senescence. Both number of roots, root dry matter and depth of rooting were less under limited soil moisture. However, rainfed crop retained more number of lengthy roots, and biomass towards later stages than irrigated crop.
Sri Lankan Cassava Mosaic Virus (SLCMV) causes mosaic disease in cassava in India, Sri Lanka and south east Asian countries. Among the 98 plants species/ cultivars belonging to seven families screened/ tested against the virus, SLCMV was transmitted to 42 species of plants belonging to Solanaceae and 4 species of plants belonging to Euphorbiaceae through whitefly inoculation. The incubation period for symptom appearance varied from 6-49 days depending on the species. Presence or absence of SLCMV in the host was confirmed through PCR.
An efficient and reproducible plant regeneration protocol for nutritionally rich varieties of sweet potato ( Ipomoea batatas L.), Gouri and Bhu Sona was developed. The effect of different hormone combinations and types of explants on shoot regeneration was evaluated to optimize the regeneration protocol. Among the explants and hormone combinations tested, only nodal explants with axillary bud of both the varieties produced shoots and the maximum per cent shoot induction in Gouri (100%) was observed in MS medium supplemented with 1.0 mg l-1 BAP and 1.0 mg l-1 BAP along with 1.0 mg l-1 GA3. Similarly, maximum per cent shoot induction (96.67%) in Bhu Sona was observed in the medium supplemented with 0.5 mg l-1 BAP along with 1.0 mg l-1 GA3 and 1.0 mg l-1 BAP. Leaf, petiole and root explants produced compact callus, which did not regenerate into shoots in shoot induction medium. Regenerated shoots were transferred to different rooting media and maximum rooting in both the varieties were observed in MS medium supplemented with 0.5 mg l-1 IBA. An efficient, reproducible plant regeneration protocol developed for sweet potato varieties, Gouri and Bhu Sona can be used for mass production of planting materials of these varieties and/or any other plant biotechnological approaches.
An experiment was conducted using 21 germplasm of Elephant foot yam including one national check to find out genetic divergence among the collected genotypes. The experiment was carried out at T.C.A., Dholi Research Farm of Dr. R.P.C.A.U., Pusa, Samastipur, Bihar, in a completely Randomized Block Design with two replications during 2018. Data were collected for ten characters viz., days to sprouting, pseudostem length (cm), pseudostem girth (cm), leaf canopy diameter (cm), chlorophyll content (SPAD value), calcium oxalate (mg/100gm), dry matter (%), days to maturity, no. of cormels per plant and corm weight per plant (kg.). Analysis of variance revealed highly significant differences among the germplasm for all the ten characters under study. Maximum range was found for the characters like pseudostem length followed by leaf canopy diameter, days to sprouting, days to maturity, chlorophyll content, pseudostem girth and no. of cormels per plant. The phenotypic coefficient of variance was greater than genotypic coefficient of variance for all the characters under study and high magnitude of phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were observed for traits like no. of cormels per plant followed by corm weight per plant, pseudostem length, days to sprouting, pseudostem girth, calcium oxalate, chlorophyll content and leaf canopy diameter indicating that these traits could be used for corm yield improvement. High estimates of heritability coupled with high genetic advance expressed as percentage of mean were observed for characters like days to sprouting, pseudostem length, pseudostem girth, leaf canopy diameter, chlorophyll content, calcium oxalate, no. of cormels per plant and corm weight per plant indicating effectiveness of selection due to preponderance of additive gene action for these traits and direct selection may be effective.
Yams (Dioscorea Spp.) yield in many parts of the world are very low compared to maximum or potential yields. Managing the spatial and temporal variability using modeling approach will be one of the ways to improve the yield. The Quantitative Evaluation of Fertility of Tropical Soils (QUEFTS) model was used for determining the region specific balanced NPK uptake requirements and recommendations for a target yield of yams. Published data from several field experiments dealing with N, P and K during the past 30 years across yam growing environments with wide range of soil and climatic conditions were used for calibration of QUEFTS model. The calibration of QUEFTS model for yams required estimation of the slope of two borderlines describing the maximum accumulation (a) and maximum dilution (d) of N, P and K in plant in relation to tuber yield. The study proposed the following ‘a’ and ‘d’ values for yam with harvest index above 0.40. The constants for minimum (a) and maximum accumulation (d) (kg tuber kg”1 nutrient) of N (137 and 363), P (1212 and 3509) and K (127 and 397) were derived as standard model parameters. The ratio of maximum dilution (d) to maximum accumulation (a) [d/a] for N (2.65) was less than that of P (2.90) and K (2.91), indicating that a specific yield of yam relied on a relatively narrow range of N uptake. Therefore, a precise N supply is more important for a stable tuber yield relative to P and K. The model predicted a linear increase in tuber yield, if nutrients are taken up at rate of 4.15, 0.45 and 3.95 kg of N, P and K per 1000 kg tuber. The average uptake ratio in total plant dry matter was 9.2:1:8.8. The optimal internal efficiencies for balanced nutrition were 240, 2222 and 253 kg N, P and K per kg of tuber.
Taro is believed to have originated in the Indo-Malayan region and hence harbors a wide genetic diversity. The major problem associated with taro cultivation is taro leaf blight (TLB) caused by Phytophthora colocasiae . Germplasm of taro maintained at ICAR-CTCRI was continuously screened for resistance for the last four years and as a result, few resistant genotypes were identified. An attempt was made here to assess the genetic diversity existing in this set along with susceptible genotypes present in the germplasm collection using ISSR. Thirty six genotypes of C. esculenta from different parts of India including five varieties were used in the study. The genotypes used were classified as resistant and susceptible based on their reactions to TLB, previous studies. Fourteen ISSR markers were used on 18 resistant and 18 susceptible taro genotypes. The primers selected were suitable for the study as reflected by the mean percentage polymorphism of 95.7%, heterozygosity ranging from 0.75-0.87, average number of alleles ranging between 1.94-6.13 and Polymorphic Information Content (PIC) ranging from 0.71-0.86. Similarity matrix based on Jaccard’s coefficient ranged from 0.50 to 0.88 and the genotypes were grouped into two major clusters. The clusters were sub-divided into four and three sub-clusters, respectively along with an outlier. Cluster I comprised of 12 resistant and seven susceptible lines whereas Cluster II had eight resistant and nine susceptible genotypes grouped together. Of the seven sub-clusters, resistant genotypes were grouped together in three sub-clusters viz., 1a, 1b and 2a. The sub-cluster 2d had only susceptible genotypes pooled together. In the rest three sub-clusters viz., 1c, 1d and 2b resistant and susceptible genotypes grouped together. In sub cluster Id, of the eight genotypes grouped together, only one was resistant, IC012470 which pooled with Sree Rashmi in the dendrogram at 88% similarity. Phenotypically the genotype IC012470 caught mild infection. This work shows that ISSR is able to assess the genetic diversity present among taro genotypes and also helped to group the taro genotypes on the basis of TLB resistance/susceptibility to a large extent. Few genetically divergent genotypes could be identified, viz., IC012593 in 1a, TCR 429 in 1b, C-565 in 1c, B4 in 2a, C-679 in 2b as well as IC089583 and B2(SVP) in 2c. The divergent genotypes identified were resistant to TLB except B2(SVP), which was susceptible. The TLB resistant genetically divergent genotypes can be used as diverse parents for development of a mapping population for TLB resistance along with susceptible sources and also for introgression of resistance to popular high yielding varieties which are susceptible to TLB.
Sweet potato is one of the major tuber crops cultivated in Telangana. Sweet potato weevil Cylas formicarius (Fab.) is one of the major constraints in its production. The present study was conducted under All India Coordinated Research Project on Tuber Crops at Vegetable Research Station, Rajendranagar, Sri Konda Laxman Telangana State Horticultural University, during the year 2016-17 and 2017-18. Among the different treatments evaluated for the management of SPW, installation of pheromone traps @ one per 100 m2 was found to be the best treatment in the management of SPW with lowest number of weevils in the collar region at 30 days (0.45) which increased during later period of 60 days (0.90), 90 days (1.40) compared to the other treatments. This treatment resulted in very good marketable yield of 14.20 t ha-1 compared to the total yield of 16.09 t ha-1 indicating better management of SPW with use of pheromones.
To evolve a suitable short duration cassava variety for the flood prone riverine alluvium of Upper Kuttanad areas, an experiment was conducted at Agricultural Research Station, Thiruvalla using three popular short duration varieties viz., Sree Jaya, Sree Vijaya, Sree Prakash from ICAR-CTCRI, Thiruvananthapuram, Vellayani Hraswa from Kerala Agricultural University, Thrissur and a landrace namely Vettikavala Local from Vettikavala, Kottarakkara. The experiment was conducted during the period from 2012 to 2016. The five genotypes (varieties and landrace) were evaluated for their growth characters, yield components and quality parameters. Among the genotypes, ‘Vettikavala Local’ performed well in yield trials and farm trials, with high tuber yield per plant (3.97 kg) while tuber had a starch content of 22.52%. Besides it possess better plant type, cooking quality and crop duration of 6 months. The genotype was found to be promising and suitable for riverine alluvium of Upper Kuttanad region and therefore it was released with the name ‘KAU Uthama’ by Kerala Agricultural University in 2018.
Root and tuber crops are those plant species that store their food inside their stem or root. They are the staple food for many people in developing countries and also a global source of carbohydrate. Cassava ( Manihot esculenta Crantz) is a root crop belonging to section Fructicosae, family Euphorbiaceae and of class Dicotyledons. Cassava is a typical diploid species with chromosome number as 2n=36. Molecular markers have proved to be valuable tools in the characterization and evaluation of genetic diversity within and between species and populations. Inter simple sequence repeat (ISSR) and simple sequence repeat (SSR) markers provide more sophisticated analysis of genetic diversity, cultivar identification, population genetic structure and other events of evolutionary biology processes. In the present study, the genetic variability among 14 indigenous accessions of cassava germplasm maintained in the field genebank of ICAR-CTCRI was estimated by molecular characterization using six ISSR and nine SSR markers. DNA was extracted from young fresh leaves of cassava using the CTAB method. The genetic distances based on ISSR markers ranged from 0.102941 to 0.231083. Among the 14 cassava accessions, the lowest genetic distance (0.102941) was observed between CI-3 and CI-2 for the 6 ISSR markers and the genetic distances based on SSR markers ranged from 0.00 to 0.283507. The lowest genetic distance (0.00) was observed between CI-3 and CI-2 suggesting that these two genotypes are similar for 9 SSR markers. The value of expected heterozygocity ranged from 0.92 (UBC 807) to 0.98 (UBC 808, UBC 817, UBC 836) and from 0.00 (SSRY 102) to 0.97 (SSRY 45, SSRY 100). The Polymorphism Information Content values ranged from 0.133 (UBC 808, UBC 836) to 0.180 (UBC 845) and from 0.000 (SSRY 102) to 0.500 (SSRY 9, SSRY 147, SSRY 148, SSRY 161) indicating the low to moderate polymorphism for these alleles.The study revealed that only two accessions (CI-161 and CI-296) exhibit 100% similarity by molecular characterization using 6 ISSR and 9 SSR markers among the 14 accessions grouped under a single core group morphologically. Hence, it is concluded that the molecular markers used in the present study can very effectively be used as tools in future for germplasm characterization, variability studies, core collection development and also diversity studies in cassava.
