Browsing by Author "Jasy, T."

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    Host preference of the burrowing nematode, Radopholus similis populations from India.
    (2007-02) Koshy, P.K.; Jasy, T.
    Host specificity study of 28 populations of Radopholus similis was done. Designated 17 host differentials to identify races of R similis. The host differentials are coconut (Cv. Laccadh/e Micro), arecanut(Var. Mangala), banana (Cv. Njalipoovan and Var. Robusta), black pepper (Var. Panniyur-1), nutmeg (Cv. Local), clove (Cv. Local), cardamom (Cv. Vazhukka), tea (Var. Ca-150), coffee (Cv. San Ramon), avocado(Cv. Furte), citrus (Cv. Musambi), pineapple (Cvs. Mauritius and Kew), sweet potato (Var. H-268) and sugarcane (Vars. Co. 449 and Co. 997). Ten races of R similis in south India were identified among die 28 populations on the basis of their multiplication on the 17 identified host differentials. Citrus, clove, pineapple and sugarcane var. Co. 997 were immune to all the 28 populations. Race I multiplied on all the 11 susceptible differentials. Nutmeg was immune to race II and nutmeg and tea were immune to race III. Race IV did not multiply on avocado and nutmeg. Black pepper was immune to race V. Race VI did not multiply on banana Cv. Njalipoovan but it multiplied on tissue cultured banana Var. Robusta and nutmeg. In addition to banana Cv. Njalipoovan.race VII did not multiplied on sugarcane Var. Co. 449, avocado, coffee and tea. Race VIII did not multiply on 4 differentials viz. black pepper, sugarcane, tea and nutmeg. Arecanut, tea and nutmeg were immune to race IX. In addition to arecanut and nutmeg, race X did not multiply on black pepper.
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    Morphometric Variability in Radopholus Similis
    (2007-02) Koshy, P.K.; Jasy, T.; Jacob Mathew; Nampoothiri, C.K.
    Morphometric studies were carried out to determine differences, if any, among the 12 populations of Radopholus similis collected from different localities of South India. Most of the measurements and ratios recorded in these studies fall within the range of measurements of R. similis reported previously. Out of the 39 characters/ratios examined, stylet length (C.V. 3.91%) and ratio V(C. V. 3.10%) were the most stable characters in R. similis. The populations developed from a single adult female on carrot discs recorded minimum variations. Comparisons of adult and gravid females of a coconut population (C17 H) from host root showed that most of the measurements were higher in gravid females, indicating the need for recording the measurements of gravid females separately in all morphological studies. D2 analysis of 39 characters of males and females grouped the 10 populations into three clusters and 12 populations fell into 4 clusters with population cultured on host root alone forming a separate cluster. Significant correlation was found between the pairs of characters constituting the ratio c and body length of females and males and ratio V of females. Body length (BL) has been found to be a good descriptive ratio in R. similis where the correlations was highly significant between the constituting characters.