Association analysis of F2 generation in rice (Oryza sativa L.) under salinity condition
Abstract
Rice occupies a pivotal place in the Indian agriculture and has been grown under diverse ecological conditions and gets exposed to different environmental stresses like drought, salinity and submergence. Development of rice varieties for salinity affected areas is emphasized on the improvement of rice yield potential in a specific environment. Information related to the relationship between yield and its components in the breeding programme particularly for salinity is very limited. Hence, the present investigation was carried out to study the correlation and path analysis in F2 generation derived from two crosses namely ADT 43 x FL478 (Cross 1) and Improved White Ponni x FL478 (Cross 2) were evaluated at a farmer’s field at Vedapatti village, Tuticorin district of Tamil Nadu which is a saline track. Another rice variety FL478 (IR 66946-3R-178-1-1, derived from crossing between Pokkali and IR 29), has been promoted as an improved donor for breeding programs, as it has a high level of seedling stage salinity tolerance and is photoperiod insensitive, shorter and ûowers earlier than the original Pokkali. FL478 also maintains a lower Na+/K+ ratio than both the parent lines (Gregorio et al. 2002). Based on its ability to tiller well and maintain high potassium content under salinity stress, FL478 appears to be a good candidate for salinity stress tolerance in rice, particularly at the vegetative stage of growth. In Vedapatti village of Tuticorin district, due to over-pumping of groundwater in the past several years, normal irrigation water has become saline water. Moreover, this village is considered as a hot spot area for the saline condition. Hence, the six generations developed through hybridization techniques were evaluated for salinity tolerance at Vedapatti village. The soil and water samples were collected from the field to analyze the EC and pH. The soil salinity and water quality in the experimental plot were 4.82 ECdSm-1 and 8.09 (pH) for soil and 4.78 ECdSm-1 and 8.19 (pH) for water respectively. From the present findings, it is clear that the characters viz., number of tillers per plant, number of productive tillers per plant, number of filled grains per panicle, total number of grains per panicle and spikelet fertility have to be given prime importance during selection since they expressed significant and positive correlation with single plant yield and also a positive inter-correlation among themselves. Therefore, selection for anyone of the above characters would bring in the simultaneous improvement of other traits and also finally resort to improve the grain yield under salinity condition. Path analysis also revealed that selection for the number of productive tillers per plant and the number of filled grains per panicle are to be given prior importance during selection since they had a positive correlation and high direct and indirect effect on grain yield under salinity condition in rice.
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