ANALYSIS OF MORPHO-PHYSIOLOGICAL DIFFERENCES BETWEEN TRADITIONAL AND IMPROVED CULTIVARS OF RICE
Abstract:
In this study, a total of twenty-two improved rice cultivars sourced from the Baddegi Rice Breeding Unit of the National Cereals Research Institute (NCRI) were evaluated alongside seventeen local cultivars obtained from farmers. The evaluation encompassed assessments of morpho-physiological traits, responses to iron toxicity, and reactions to the African rice gall midge (AfRGM). The experimentation was conducted over two consecutive years (2009 and 2010) at the Edozhigi substation of the National Cereal Research Institute.
The experimental design employed a randomized complete block design (RCBD) with three replications. Eleven morpho-agronomic characteristics were utilized to characterize the studied materials. The collected data underwent analysis of variance (ANOVA) using Genstat 5 (2004), as well as multivariate techniques including Principal Component Analysis (PCA), correlation analysis, Euclidean distance with complete linkage, and cluster analysis.
The ANOVA results indicated significant differences (at the 1% probability level) in plant height, leaf width, gall midge count at 62 days after transplanting (DAT), iron toxicity score at 20 DAT, and total yield per plot. Conversely, no significant differences were observed in gall midge count at 42 DAT, iron toxicity scores at 40 DAT and 60 DAT. In the second year, leaf length, panicle length, iron toxicity scores at 20 DAT and 40 DAT, days to 50% flowering, leaf width, and total yield per plot exhibited significant differences at the 1% probability level.
The combined analysis of the two-year data led to a cluster analysis that delineated three groups based on similarities in varietal characteristics. Group one encompassed four local and two improved varieties, while group two consisted of twenty-six varieties, twelve of which were local and fourteen improved. Group three contained five varieties, two of which were local and three improved. Correlation analysis of morphological traits across the two years revealed positive correlations between panicle length and weight of 1000 grains, gall midge count and weight of 1000 grains, gall midge count and days to 50% flowering, and gall midge count and leaf width. Conversely, negative correlations were found between iron scores and plant height.
Principal Component Analysis (PCA) of the combined two-year data highlighted that the first five principal components accounted for 65.4% of the total variation. Notably, phenotypic acceptability, weight of 1000 grains, and leaf length made significant contributions to this variation. The scatter diagram depicted variations among the variables.
The study indicated that no cultivar exhibited immunity to the African Rice Gall Midge (AfRGM). However, the local varieties Ndawodzufugi and Babawagi demonstrated resistance reactions at 62 DAT in the first year. Most cultivars exhibited responses ranging from moderately resistant to moderately susceptible (scores of 3 to 5) to both AfRGM and iron toxicity. Notably, the NERICA L36 and Mass varieties exhibited substantial variation compared to other entries, suggesting their potential as valuable parent candidates for breeding programs. Additionally, further screening of Ndawodzufugi and Babawagi varieties was recommended to ascertain their precise level of tolerance.
The study facilitated the categorization of cultivars into coherent agronomic groups, offering a foundation for selecting varieties with consistent morphological attributes to serve as parents in future rice improvement initiatives.
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