Browsing by Author "Jacob, P.M."

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    Analysis of population structure and genetic relatedness among root (wilt) disease-resistant and susceptible west coast tall coconut palms (Cocos nucifera) using microsatellite markers
    (2011-06) Devakumar, K.; Thomas, R.J.; Nair, R.V.; Augustine Jerard, B.; Rajesh, M.K.; Jacob, P.M.; Jayadev, K.; Parthasarathy, V.A.
    The population structures among the root (wilt) disease-resistant and susceptible coconut palms from 12 locations in the three disease-endemic districts of southern Kerala, were analyzed using nine microsatellite markers. The pair-wise population differentiation estimate (Fs) between the resistant and susceptible populations was 0.021. Two major populations and a subpopulation cluster were identified among the resistant palms. The analysis of genetic relatedness between the resistant mother palms showed that most of the palms located in a single locality shared sib relationship among them. The existence of close genetic relationship among resistant palms from Chengannur, Thiruvalla, Kottayam and Pavukkara localities in Kerala were reported. The results are discussed in terms of breeding strategies for increasing heterozygosity and obtaining the maximum number of disease-resistant seedlings.
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    Breeding for resistance/tolerance to root (wilt) disease
    (2007-02-08) Nair, R.V.; Jacob, P.M.; Koshy, P.K.; Sasikala, M.; Nampoothiri, K.U.K.
    Root wilt is a serious disease of coconut in Kerala. The disease affects 16 million palms and cause an annual loss of 968 million nuts. Involvement of phytoplasma in the etiology of this disease has been established. Breeding for evolving root (wilt) resistant varieties - being the lasting solution for the disease is implemented since 1987. In the heavily diseased tracts, some high yielding west coast tall and chowgate green dwarf palms were found to be resistant and serologically negative under field conditions. Studies indicated that CGD palms were having higher level of resistance to the disease compared to that of other varieties. It has also been reported that CDO X WCT hybrids gave higher yield in spite of contracting the disease. Based on these,observations, the following crosses are made - WCT X WCT (inter-se), WCT (self), WCT X CGD, CGD X WCT, CGD (self/inter-se), CDO (self/inter-se). The present crossing programme includes 63 WCT, 97 CGD and 4 CDO palms in the farmers plots.The 2725 progenies were under planted among heavily infested palms for evaluating their resistance and use them as future mother palms. In the seventh year of planting, WCT (open pollinated) seedlings showed 60%disease incidence where as WCT (self) and WCT (inter-se) showed 45% disease incidence and only 31% in CGD X WCT. Four seed gardens have been established by planting 3371 artificially pollinated seedlings.
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    CGDxWCT hybrid - an ideal planting material for root (wilt) disease endemic areas
    (2007-02-08) Jacob, P.M.; Iyer, R.D.; Nair, R.V.; Nampoothiri, K.U.K.
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    Chowghat Green Dwarf - A suitable variety for the coconut root (wilt) diseased tract
    (2007-02-08) Nair, R.V.; Rajesh, M.G.; Jacob, P.M.
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    Comparison of enzyme activities with diagnostic potential in healthy and root (wilt) diseased coconut palms, differing in cultivars and growth stages
    (2012-08) Chaturvedi, V.K.; Srinivasan, N.; Sasikala, M.; Jacob, P.M.; Rajeev, G.
    Activities of superoxide dismutase (SOD), succinic dehydrogenase (SucDH), exochitinase (Cht) and 1, 4 β-glucanase (Glucn) were quantified to assess their diagnostic potential for detection of, or their role in imparting tolerance against, root (wilt) disease (RWD). The enzymes were determined in healthy and infected palms of contrasting coconut cultivars - Chowghat Green Dwarf (CGD) and/or Malayan Green Dwarf (MGD) tolerant and West Coast Tall (WCT) - susceptible, in the adult palms and in some at the seedling growth stage. Healthy and RWD plants differed little and that too inconsistently with respect to the activities, specific activities and soluble protein content of all the 4 enzymes, offering no diagnostic potential, in the three cultivars. However, cultivars and growth stage differences for enzyme activities were found to be significant for some enzymes. The RWD tolerant cultivar CGD (10-year old palms) had higher SOD and SucDH activity, higher soluble protein in the SOD and SucDH extract and lesser SOD specific activity than the RWD susceptible cultivar WCT (40-year old palms). The RWD tolerant cultivar MGD had lesser SOD activity than WCT in the seedling stage, lesser SOD specific activity in the adult stage (15-year old palms), higher SucDH activity and specific activity, higher soluble protein in the SOD extract, but lesser soluble protein in the Cht extract than 40-year old WCT adult palms. Seedlings of WCT and MGD had higher SOD activity than their adult plants. Seedlings of WCT and CGD had higher soluble protein in SOD extract than their adult plants. Seedlings of CGD had higher soluble protein in SucDH extract than its adult plants. Metabolic differences in enzyme activities indicated that the cultivars CGD followed by MGD and the seedling stage or younger plants seem to have a better capacity in resisting the effects of root (wilt) disease.
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    Development of varieties of coconut (Cocos nucifera L) resistant/tolerant to root(wilt) disease
    (2004-12) Nair, R.V.; Jacob, P.M.; Thomas, R.J.; Sasikala, M.
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    Exploration and collection of coconut germplasm in Kadmat and Amini Islands of Lakshadweep, India
    (Springer, 2006) Samsudeen, K.; Jacob, P.M.; Niral, V.; Kumaran, P.M.; Radha Salooja; Moosa, H.
    Coconut, Cocos nucifera L. is an important plantation crop of the tropics. Lakshadweep group of islands in the Arabian Sea are considered to be home to some important coconut cultivars. The present exploration was planned to sample the variability within the population of Laccadive ordinary tall (LCT), Laccadive micro tall (LMT) from two islands, Amini and Kadmat, of Lakshadweep. Sampling was done from 24 sites in Amini and 13 sites in Kadmat. On an average 10 palms were sampled from each site. During the trip, five accessions of LCT, three of LMT and one of Kaithathali were collected. Eight fruit component measurements were recorded to study the variability in the population. Intra-population variability was observed in both LCT and LMT. Three forms of LCT belonging to niu kafa, niu vai and introgressed types could be identified. Elongated angular fruits (elliptical) with 70% husk were niu kafa types, round or oval shaped ones with 55% husk were niu vai types and pear shaped ones with 58% husk were the introgressed forms. This exploration trip unearthed the missing link of niu vai type in the form of round fruit type which has not been reported earlier. Identification of different groups in LCT has far reaching implications in breeding. In the production of hybrids involving LCT, selection of mother palms of LCT is crucial. It is suggested that the elliptical fruit types may be avoided in the production of commercial hybrids, since it has high percentage of husk.
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    Fruit component analysis in Lakshadweep coconuts
    (2007-02) Krishnamoorthy, B.; Jacob, P.M.
    The Niu kafa-Niu vai Introgression (NKNVI) method was used for the comparison of the different types of coconut found in Lakshadweep Islands. The highest proportion of husk in the fruit and a high proportion of endosperm in the nut are characteristic of the Niu Kafa class, while, a tow proportion of husk and high proportion of water in the nut are characteristic of theNiu vai class. Fruit component analysis indicated that the different types of Lakshadweep coconuts belong typically to the "Niu kafa" class and the Laccadive Small is of intermediate nature, and arose perhaps due to introgressive hybridization between the Laccadive Micro and the Laccadive Ordinary types.
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    Genetic purity assessment of D x T hybrids in coconut with SSR markers
    (2012) Rajesh, M.K.; Thomas, R.J.; Rijith, J.; Shareefa, M.; Jacob, P.M.
    Assessment of genetic purity in coconut hybrids was done using molecular markers. A set of 50 hyperpolymorphic coconut SSR markers were utilized to characterize parental lines Chowghat Green Dwarf (CGD) and West Coast Tall (WCT) used for hybrid coconut production. A panel of 17 informative SSR markers capable of distinguishing these parental lines was identified and these markers were utilized in DxT hybrid seedling purity assessments in coconut nurseries.
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    Hybrids and Hybridization techniques in coconut
    (2011-09) Regi J. Thomas; Shareefa, M.; Jacob, P.M.
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    Identification and critical study of eilte palms to evolve an ideal plant type in coconut
    (Central Plantation Crops Research Institute Regional station Kayangulam, 1982) Iyer, R.D.; Rao, E.V.V.B.; Sukumaran, C.K.; Jacob, P.M.; Viveknath, B.C.; Govindankutty, M.P.
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    Incidence of root (wilt) disease in various cross combinations of west coast tall variety of coconut
    (2003) Nair, R.V.; Jacob, P.M.; Rajesh, M.G.; Thomas, R.J.
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    Increasing Production and Productivity in the Existi Coconut Gardens of Lakshadweep Islands
    (2007-02) Jacob, P.M.; Keshava Bhat, S.; Vasanthasenan, R.
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    IND 030-Laccadive Micro Tall (IC0430669; INGR13060), a Coconut (Cocos nucifera) Germplasm with Cluster Bearing Heavy Bunches of Micro Nuts
    (2014) Niral, V.; Augustine Jerard, B.; Samsudeen, K.; Nair, R.V.; Jacob, P.M.; Devakumar, K.; Ratnambal, M.J.; Kumaran, P.M.; Bhaskara Rao, E.V.V.; Pillai, R.V.; George V. Thomas
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    Kalparaksha, a new coconut variety, resistant to root (wilt) disease
    (2009-05) Nair, R.V.; Thomas, R.J.; Jacob, P.M.; George V. Thomas
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    Management and conservation dilemmas surrounding a Near-Threatened grasshopper, Aularches miliaris Linn. (Orthoptera: Pyrgomorphidae) in south India
    (2011) Josephrajkumar, A.; Rajan, P.; Chandra Mohanan, R.; Jacob, P.M.
    The world is facing severe biodiversity loss and agencies worldwide are attempting to stem this threat. However problems arise when a rare or threatened species is also an agricultural or medical pest. In this paper we discuss the case of Aularches miliaris, the spotted coffee grasshopper. This species exists as several subspecies across south Asia, perhaps representing local genetic adaptation. It is polyphagous and a minor agricultural pest, and is usually managed via insecticides and egg-bed destruction. For much of its range, populations appear healthy and are not threatened. In contrast, within the Western Ghats Biodiversity Hotspot in south India, A. miliaris is sparse and listed as Near-Threatened. In this area the insect is an occasional minor agricultural pest. Considering its local rarity, versus its abundance in other geographic areas, we recommend that in south India A. miliaris needs to be conserved at the present time. During localized outbreaks, we recommend that A. miliaris be managed via mechanical collection of nymphs and adults, and destruction of egg pods, rather than intervention using insecticides.
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    Microsatellite analysis of distinct coconut accessions from Agatti and Kavaratti Islands, Lakshadweep, India
    (Elsevier, 2010) Devakumar, K.; Niral, V.; Augustine Jerard, B.; Jayabose, C.; Chandra Mohanan, R.; Jacob, P.M.
    The Lakshadweep group of islands, located in the south-western part of India in the Indian Ocean is considered unique for its coconut populations owing to its geographic isolation and assumed introgression with mainland coconut populations along west coast of mainland India. A wide range of variability was noticed for morphological characters of Lakshadweep coconut populations. A total of nine accessions were collected from Agatti and Kavaratti Islands of Lakshadweep as part of a germplasm enrichment programme for island coconut populations of India. This includes three Laccadive Micro types, four types of Laccadive Ordinary Tall differing in nut bearing habit, fruit shape and size, one each of sweet husked Kaithathali tall and dwarf type. The microsatellite analysis of the 9 coconut populations with 8 primers revealed a total of 37 alleles. The highest number of eight alleles was detected for the CAC8 primer and the lowest number of three alleles for the CAC10, CAC13 and CnCIRG11 primers. The estimate of heterozygosity was highest (>0.5) for the two Laccadive Micro Tall (LMT02 and LMT03) and the Laccadive Small Tall (LCT02) populations and was lowest (0.24) for the Laccadive Micro Tall (LMT01). The sporadic occurrence of Laccadive Micro Tall is discussed in the context of high outcrossing and inbreeding depression.
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    Observations on the Coconut Genepool in Lakshadweep Islands
    (2007-02) Jacob, P.M.; Krishnamoorthy, B.
    The coconut palms in Lakshadweep Islands are high yielding, free from major diseases and are in highly over crowded stands. Laccadive Ordinary, Laccadive Micro, Kaithathalli and Dwarf palms bearing green and orange nuts are the types cultivated in these islands. Laccadive Micro is a high yielding cultivar with highest oil content in copra among all cultivars. However, the population of this cultivar has been on the decline due to introgression resulting in the intermediate types between Laccadive Ordinary and Laccadive Micro. The vegetative and nut characters of Laccadive Ordinary population have been studied. The Islands were surveyed for locating the available Laccadive Micro palms. Androth Island has got the maximum number of Laccadive Micro palms. An improved germination technique has been developed for Laccadive Micro, by which 80% germination was realised instead of the 49% obtained in the field conditions.