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Contribution of Characters Towards Divergence in BRRI-released Modern Boro Rice Varieties

M. R. Zaman
Agricultural Statistic Division, Bangladesh Rice Research Institute, Gazipur, Bangladesh

M. A. Hossain
Plant Breeding Division, Bangaldesh Rice Research Institute, Gazipur, Bangladesh

D. N. R. Paul
Agricultural Statistic Division, Bangladesh Rice Research Institute, Gazipur, Bangladesh

M. S. Kabir
Agricultural Statistic Division, Bangladesh Rice Research Institute, Gazipur, Bangladesh

M. Zakir Hossain
Seed Certification Agency, Gazipur, Bangladesh

Abstract/ Executive Summary:

An experiment was conducted at the Bangladesh Agricultural University, Mymensingh during 2000-01 to identify rice varieties and their time of harvest. Assessment of character contribution towards divergence in 20 modern rice varieties was done during Boro, 2001-2002 seasons. Contributions were assessed with 8, 7, 6 and 5 characters separately. For all the cases Mahalanabis D² values were calculated and distant and closer pairs were identified. In all the cases days to flowering and plant height contributed consistently to the total divergence. Flag leaf angle consistently contributed at lower percentage (2.1-5.8) to the divergence. From the distance matrix tables of Mahalanobis D² analysis, BR18 and BR19, BR7 and BR9, and BR2 and BR9 were found as the closest pairs and BR6 and BR12 were found most distant pairs. It was observed that among the Boro varieties, yield, tiller number, filled grains per panicle were the less contributing characters towards the total divergence. Breeding for the improvement of those characters, therefore, have little possibility in these Boro varieties. However, there is a scope to improve days to flowering and plant height using those varieties.

Keywords: Divergence, Character contribution, 50% flowering, Plant height, 1000-Grain weight

Location: Bangladesh Agricultural University, Mymensingh

Start Date: 00-00-2001

End Date: 00-00-2002

Program Area: Crop-Soil-Water Management

Commodity: Rice

Objectives:

To estimate the contribution of different characters to the total divergence considering 8, 7, 6 and 5 characters avoiding each time the less contributing one. The pair wise distance was estimated in each case to identify the right pair for using in hybridization program.

Methodology:

The experiment was conducted in Boro 2001- 2002 with 20 modem varieties (MVs) of rice following RCB design with three replications. The plot size was 24 m² with planting spacing of 20×20 cm, Standard crop management practices were done to maintain normal crop growth. From each plot 10 m² was identified during maximum tillering stage for grain yield estimation and the rest 14 m² area were used for taking other necessary data. Ten plants were randomly selected for measuring plant height (cm), number of panicles per hill, filled grains per panicle, and 1000-grain weight (g). Flag leaf angle (^o) and upper three leaves area (cm²) were calculated from middle most and longest tillers of 5 hills during flowering just after the complete emergence of the panicles. Matured crop was harvested and grain yield was calculated at 14% moisture content Mahalanabis D² determines the distance between any two varieties based on common characters measured on each variety. Contribution of each character towards divergence was calculated taking into consideration all combinations. Each character was ranked on the basis of the different value for each combination and thus rank-1 was given for the highest value for each combination. Contribution of a character towards divergence was estimated in percentage with how many times that particular character ranked as lout of total number of combinations. To classify the BRRI released boro varieties, at first eight characters were considered and their contributions towards divergence were assessed. The characters showing the null or almost null contribution were excluded one by one and the contribution was reassessed. In such way, character contribution assessment was done with 8, 7, 6 and 5 characters separately. For all the cases Mahalanabis D² values were calculated and distant and closer pairs were identified.

Source of Information: The Agriculturists 2(1): 141-145 (2004); ISSN 1729-5211

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Days to 50% Flowering is the least variable plant character and the largest contributor, contributing about two-third or more to total divergence of rice genotype. Plant height and 1000-grain weight stand at second and third position, respectively in terms of contributions to genotypes divergence. The contributions of other plant characters to total divergence were small to nil and hence there is a very little scope to improve these characters with the existing BRRI released varieties.

Knowledge Management: Journal