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Subject: Nematology × End date: 2020 × Start date: 2020 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Morphological and morphometric variations of Hoplolaimus and Helicotylenchus
    (AAU, Jorhat, 2020-08) Venkadesh, G; Das, Debanand
    Investigations were carried out to study the morphological and morphometric variations of genera Hoplolaimus and Helicotylenchus in relation to host plants and geographical locations of Assam. Total of 163 soil samples were collected from Rice, Maize, Banana, Mango, Jackfruit, Citrus, Pea and Tea, and from different geographical locations viz., Jorhat, Kokrajhar, Sivasagar, Kamrup, Lakhimpur, Dhemaji, Nagaon and KarbiAnglong district of Assam. The populations of both genera under survey were identified as Hoplolaimus columbus, Hoplolaimus indicus, Helicotylenchus crenacauda and Helicotylenchus dihystera. In the study no morphological variations have been observed in genera Hoplolaimus and Helicotylenchus in relation to both host plants and geographical locations. Results of morphometric characters showed that body length, a ratio, oesophagus length, b ratio, oesophageal gland overlapping length, bʹ ratio, ABW, MB, V, Vʹ, stylet length, SE and Pp (only in Hoplolaimus) were regards as least variable characters and considered highly stable in relation to host plants for genera Hoplolaimus and Helicotylenchus. The c ratio, number of tail annules and Pa of females were least variable characters; while, tail length and cʹ ratio were moderately variable characters in Hoplolaimus columbus. The c ratio, cʹ ratio, number of tail annules and Pa of females were regarded as moderately variable characters; while, tail length of females was regarded as highly variable character in Hoplolaimus indicus. In males of H. indicus, tail length, c ratio, cʹ ratio and Pa were regarded as least variable characters; while, bursa of males was regarded as moderately variable character. The tail length, c ratio, cʹ ratio and O of females were regarded as moderately variable characters in relation to host plants of Helicotylenchus dihystera. Influence of geographical locations on morphometric characters revealed that the body length, a ratio, oesophagus length, b ratio, oesophageal gland overlapping length, ABW, MB, V, Vʹ, stylet length and Pp (only in Hoplolaimus) were least variable characters and considered highly stable characters in relation to geographical locations for genera Hoplolaimus and Helicotylenchus. The bʹ ratio, c ratio, cʹ ratio, SE and number of tail annules were least variable characters; while, tail length and Pa of females were moderately variable characters in Hoplolaimus columbus. The bʹ ratio, c ratio, cʹ ratio, SE, number of tail annules and Pa of females were moderately variable characters; while, tail length of was highly variable character in females of Hoplolaimus indicus. In males of H. indicus, bʹ ratio, tail length, SE, Pp, spicule length and gubernaculum length were least variable characters; while, c ratio, cʹ ratio, Pa and bursa of males were moderately variable characters. In case of Helicotylenchus crenacauda the bʹ ratio and SE of females were regarded as least variable characters; while, tail length, c ratio, cʹ ratio and O of females were moderately variable characters. The bʹ ratio, tail length, c ratio and SE of females were regarded as least variable characters; while, cʹ ratio and O of females were regarded as moderately variable characters in relation to geographical locations of Helicotylenchus dihystera.