Morphological characterization of wild rice (Oryza rufipogon Griff.) of NBU campus (West Bengal) for in situ conservation and germplasm enhancement

Abstract

Asian wild rice Oryza rufipogon Griff. (Poaceae) is considered as a progenitor of the cultivated rice (Oryza sativa L). lt is a source of many biotic and abiotic stress tolerance genes and these are utilized for genetic improvement of cultivated rice. Thus it needs immediate attention with high priority so that we could not loss this agriculturally important Oryza gene pool. Natural population of Oryza rufipogon in the North Bengal University campus is characterized based on phylogeographic and morphological parameters for conservation purposes. Twenty-five plants were considered randomly to measures twenty-six different types of morphological passport data for genetic relatedness analysis within the population. Diagnostic characters are provided to delineate the species morphologically. Plant is annual ecotype having short to intermediate culms height (64 cm-145 cm), and 0.5- 1.6 cm in thickness. Profuse fibrous roots of 2 mm thick and 3-9 cm long creamy-white in colour grows from the floating nodes, node region is solid and pinkish in colour (5-7 mm long). Flag leaf length ranges from 13 cm-40 cm with 0.3 cm 1.8 cm width. Flag leaf blade attitude is varying from deflexed to horizontal to semierect. Auricle was hard, curved, glabrous and 13-15.5 mm in size. Two-cleft ligule length ranges 17 mm to 35 mm. Panicle length varies from 15.4 cm 30 cm with l cm-8 cm wide with 5-13 primary branches. Attitude ofprimary branches is spreading, well exserted (100%), alternately arranged on the wavy axis. Length of the lemma varies 6-11 mm and 1.4-2.3 mm wide, lemma-awn junction marked by a pinkish pubescent constriction with 23-80 mm long red awn. Yellow colour anthers vary in length 4-8 mm long. Stigma was bifurcated (>2 mm) and purple in colour comes out from the spike lets. Seeds (blackish) are harvested during November-December and vary in length (7.5 mm - 10 mm). Density of fertile spikelets ranges from 15 to 82. Grain length/breadth ratio was 3.73 (average) and average kernel length/breadth ratio was 3.99. The results suggest that the population of NBU campus are genetically diversified, heterogeneous and should be conserved in situ to protect this precious genetic resource as separate ecological race (ecotype or intergrade) for germplasm enhancement.