Locations Of Tamil Nadu Research Articles

Morphological and molecular characterisation of Pythium species causing chilli (Capsicum annuum L.) damping-off

Twenty-five Pythium isolates comprising five species viz., Pythium aphanidermatum, P. deliense, P. graminicola, P. heterothallicum and P. ultimum from different geographical locations of Tamil Nadu (Coimbatore, 4; Cuddalore, 6; Dindigul, 1; Dharmapuri, 1; Erode, 1; Madurai, 1; Namakkal, 7; Thanjavur, 1; Theni, 1; Thirunelveli, 1 and Vellore, 1) isolated from chilli crop were analysed with randomly amplified polymorphic DNA (RAPD) markers. Morphological and molecular characteristics of these different species were correlated with the RAPD. Polymerase chain reaction amplification of total genomic DNA with six random primers generated unique banding patterns depending on the primer and the isolate. The isolate I17 produced identical banding patterns, while other isolates produced dissimilar bands within the particular species, indicating the genetic diversity among the isolates within a species. Morphological characters were also different from each other even in isolate I17 which shared identical bands. Cluster analysis showed minimum and maximum per cent similarities among the tested Pythium species which ranged from 49 to 89%, respectively. RAPD markers were better suited for differentiating isolates within a species rather than species.

Genetic diversity in Azima tetracantha (Lam) assessed through RAPD analysis

Azima tetracantha is a shrub known for its various therapeutic properties. Genetic diversity was analysed using RAPD primers among six accessions collected from different locations of Tamilnadu, India. Genetic distances were calculated using Nei's coefficient. Dendrogram was constructed on the basis of the similarity matrix data by unweighted pair group method with average (UPGMA) cluster analysis. The analysis with RAPD markers revealed wide variation within A. tetracantha that reflected a high level of diversity within this species.

Genetic diversity in Azima tetracantha (Lam) assessed through RAPD analysis

Azima tetracantha is a shrub known for its various therapeutic properties. Genetic diversity was analysed using RAPD primers among six accessions collected from different locations of Tamilnadu, India. Genetic distances were calculated using Nei’s coefficient. Dendrogram was constructed on the basis of the similarity matrix data by unweighted pair group method with average (UPGMA) cluster analysis. The analysis with RAPD markers revealed wide variation within A. tetracantha that reflected a high level of diversity within this species. Keywords: Azima tetracantha, genetic diversity, RAPD.

BALANCED FERTILIZATION IN PAPAYA (CARICA PAPAYA L.) FOR HIGHER YIELD AND QUALITY

Papaya is considered as an exhaustive crop as it is a heavy yielder besides demanding large quantity of nutrients. Fertilizer treatments involving four graded levels of potash fertilizer (0, 150, 300 and 450 K 2 O g/plant/year) along with N 300 and P 2 O 5 300 g/plant/year on growth, yield and quality were assessed over a period of three years in cvs. CO 2 and CO 7 in five different locations in Tamil Nadu, India. The stem girth was not affected significantly by potassium nutrition in four locations, while at one location potassium nutrition exerted a significant influence on the stem girth. The leaf number was significantly influenced with the application of potassium nutrition up to 300 g/plant/year in one location and up to 450 g/plant/year in two locations. The fruit yield per plant and its components viz., fruit number and single fruit weight increased significantly with the application of potassium up to 300 g/plant/year and thereafter it declined. The potassium nutrition improved the fruit quality characters like TSS, pulp thickness and carotenoid content in yellow and red fleshed varieties. The latex quality as assessed by its tyrosine content was perceptibly influenced by increased dose of potassium application up to 300 g/plant/year. From the overall studies, it is concluded that balanced fertilization with N 300 , P 2 O 5 300 and K 2 O 300 kg/ha/year is recommended for papaya to get higher yield with quality fruits per latex in papaya.

A glimpse of lignicolous marine fungi occurring in coastal water bodies of Tamil Nadu (India)

In the present investigation, a total of 51 marine fungi were obtained from wood samples collected from four locations of Tamil Nadu (Tuthukudi, Chennai, Kanyakumari and Pichavaram), India. Out of these 51, 28 were ascomycetes, one was basidiomycete and 22 were mitosporic fungi. Maximum fungal diversity was encountered from Tuthukudi, followed by Chennai, Kanyakumari, and the minimum from Pichavaram. Periconia prolifica was the only species common to all the four locations. To cite this article: G.R. Nambiar et al., C. R. Biologies 331 (2008).

Analysis of variability among the isolates of Peronosclerospora sorghi from sorghum and cornbased on restriction fragment length polymorphismof ITS region of ribosomal DNA

Downy mildew, caused by Peronosclerospora sorghi [Weston and Uppal (Shaw)], is one of the most serious diseases of sorghum and corn worldwide. Pathogenic variability among various isolates of P. sorghi has been reported. However, the molecular relationships between the isolates from sorghum and corn are unknown. In the present study DNA was extracted from P. sorghi isolates from sorghum and corn collected from different locations of Tamil Nadu, India, and their genetic variability was investigated using restriction fragment length polymorphism (RFLP) analysis of the PCR-amplified internal transcribed spacer (ITS) region of ribosomal DNA. PCR amplification of the ITS regions of the P. sorghi isolates from sorghum and corn gave products of approximately 550 base pairs in length with slight variations in a few isolates. Restriction fragment length polymorphism analysis of the ITS regions of nuclear rDNA of P. sorghi with HhaI, EcoRI and MspI confirmed the heterogeneity among the P. sorghi isolates from sorghum and corn.

Characterization of Aluminous Clays from Tamilnadu

Plastic aluminous clays are abundantly available in Tamilnadu. However, at present the utilization of these clays is very low due to lack of detailed characterization. In the present work, the green and fired characteristics of clays obtained from three different locations in Tamilnadu (Udayarpalayam, Panruti and Neyveli) have been investigated to assess their potential use as raw materials. Physical properties, plasticity index, particle size analysis, chemical analysis, X-ray diffraction and thermal analysis of these clays have been carried out. Physical properties such as density, bending strength, X-ray diffraction and scanning electron microscopy of the fired samples have also been carried out. The properties of the above three clays are compared with each other. The results show that these clays are plastic in nature containing a moderate amount of impurities with high alumina content.

CHARACTERISTICS OF THE ISOLATES OF BLB ORGANISM

Eighteen pathogenic isolates of Xanthomonas campestris pv. oryzae (Xco) were collected from seventeen locations in Tamil Nadu. Tetracycline exerted maximum inhibitory effect on the growth of all isolates. Isolate Isproduced the smallest lesion. Based on the leaf area blighted on the susceptible T(N) 1 rice variety, isolates, 11, 12 and Is were classified as most virulent, isolates 14.15,1617.19.110.111.12.16 and I18 as virulent and the isolates 13. Igand Isas least virulent. The reaction of the five international differential rice varieties have reacted to these 18 isolates differentially. Based upon the IRRI standard on the classification of race groups, Xco isolates. 13,Igand 115 are considered to belong to race group 2 and the rest of the 15 isolates belong to race group 3 of Philippines.