Received: 15 December, 2011. Accepted: 12 May, 2012. Original Research Paper International Journal of Plant Breeding ©2012 Global Science Books Existing Status and Genetic Divergence of Agro-Morphological Characters in Bangladeshi Fine Rice Bhabendra K. Biswas 1* • Nazmul Alam 2 • Jaime A. Teixeira da Silva 3 • Mohammad M. Haque 1 • Mohammad A. K. Azad 1 • Mohammed K. Hossain 1 1 Department of Genetics and Plant Breeding, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh 2 Department of Botany, Jahangirnagar University, Savar, Dhaka, Bangladesh 3 Faculty of Agriculture and Graduate School of Agriculture, Kagawa University, Ikenobe, Miki-cho, 761-0795, Japan Corresponding author: *professorbiswas@gmail.com ABSTRACT A set of 30 rice (Oryza sativa L.) cultivars including 28 primitives, one exotic and one improved variety were collected from different agro-ecological zones of Bangladesh. The experiment was conducted in a randomized complete block design with three replications during the wet season (July-December) of 2009 at the Plant Breeding Field Laboratory, Hajee Mohammad Danesh Science and Technology University, Dinajpur. The existing status regarding cultivation and preservation attitude were realized through an oral interview with 20 randomly selected farmers of each location from where a particular cultivar was collected. Four cultivars (‘Kalozira’, ‘Badshabhog’, ‘Zethakatari’, ‘Katari’) were most preferred by innovative farmers due to their use as food and in different traditional and religious festivals. Cultivars such as ‘Shilkamal’, ‘Binnipakri’, ‘Darkashail’, ‘Dudshar’, ‘Lalchikon’ and ‘Uknimodhu’ were rarely cultivated, hence the need to preserve them. The 30 cultivars were grouped into 7 clusters through principal component analysis and D 2 statistics based on 12 agro-morphological characters. Cluster VI comprising ‘BR34’ and ‘Darkashail’ produced the highest yield (4.05 t/ha). Days to maturity was generally high in all 7 clusters and ranged from 112.7-132.3 days; no cultivars matured slowly. Therefore, the development of rapidly maturing varieties by conventional breeding is assumed to be very difficult in fine rice. Among the 12 characters, spikelets/panicle exerted maximum weighting (20.37%) on total genetic divergence while percentage sterility had the least weighting (3.58%). Since highest intercluster distance (651.88) was observed between clusters III (‘Malshira’, ‘Chiconsarna’, ‘Lalchicon’, ‘Radhunipagal’, ‘Nazirshail’, ‘Lalfota’, ‘Sumonsarna’) and VI (‘BR34’, ‘Darkashail’), parents could be selected from these two clusters to obtain desirable segregants in the F 2 generation. Alternatively, one parent from each cluster could be selected to initiate a diallel cross to assess the best cross combination and to identify those parents with high general combining ability for improvement. _____________________________________________________________________________________________________________ Keywords: breeding exercise, D 2 statistics, farmers’ attitude, improvement, land race Abbreviations: BRRI, Bangladesh Rice Research Institute, GCA, general combining ability; PCA, principal component analysis INTRODUCTION Rice is the world’s most important crop and a major source of nutrition for about two-thirds of humans (Vaughan et al. 2003) and it is the staple food consumed by more than half of the world population, three billion of which are Asian (Waghmare et al. 2008) and more than 90% of the world’s rice is grown and consumed in Asia where 60% of the earth’s population live (Khush 1997). In Bangladesh, rice is extensively cultivated over a large area covering about 74% of the total human calorie intake; about 10.77 million ha of land is used for rice cultivation, which produces 25.18 million metric tons of rice (Latif et al. 2011). For most developing countries, rice is the basis of food security and is intimately associated with traditional cultures and cus- toms in local regions (Lu and Snow 2005). Fine rice may be aromatic or non-aromatic; when the grain is large, the length will exceed the breadth con- siderably but when the grain is small, it may be any type either small or slender. Independent of the grain type, all rice grain has a high market price and socio-cultural im- portance in Bangladesh. Fine rice production has been sig- nificantly increased in recent years, reaching the maximum level of quality and fetching a much higher premium (>$1/kg) than coarse rice. The coarse rice grain is bold and large having a lower market price (<$0.5/kg). Bangladesh rice breeders are keen to understand the genetic diversity of fine rice cultivars so as to be able to improve them. Most of the fragrant rice cultivars are traditional but none of them is ‘Basmati’, which has a tall stature, low yield, insensitive to photoperiod, susceptible to diseases and pests and unres- ponsive to higher doses of fertilizers (Rani 2012). In Ban- gladesh, there is a wide range of land races with unique flavor and other attractive grain characteristics such as dis- tinct grain texture, endosperm chalkiness, non-stickiness of cooked rice, etc. (Hosan et al. 2010). Thus, there is a wide scope in breeding programmes to improve fine rice to fulfill divergent demands of farmers and consumers regarding food security, changing palatability, nutrition supply, miti- gation of risk due to sudden failure of modern or hybrid varieties, good economic return, uses in socio-cultural prog- rams, among others (Hien et al. 2007). This study takes one step closer to creating such programmes. Agriculture relies heavily on the genetic diversity of crop plants. Ever since the very beginning of agriculture (more than 10000 years ago), through the process of domestication and acclimatization of crop plants, a wealth of genetic diversity was selected and partly preserved, although it is estimated that not even 15% of the potential diversity has been utilized. Thousands of valuable allelic variations of economically significant traits remain unatten- ded in nearly all crop plants which could be effectively explored to meet the existing and emerging challenges that threaten world food security (FAO 2002). Estimating gene- tic diversity and similarity among genotypes of any species has various applications in plant breeding. A population with numerous diverged genotypes plays a key role in the success of any breeding program since the parents involved ®