Introduction

Rice (Oryza sativa L.) is the most important cereal crop of the world. Bangladesh is one of the larger producers and consumers of rice as Agriculture is the single largest economic sector of the country. Bangladesh is currently self-sufficient for rice production in the context of shrinking rice land and water resources, lower national average yield and changing global climate. Therefore, rice diversity as well as its traits and genes, need to be considered in future for developing new varieties. Tilman et al. (2001) also reported that use of crop diversity is one of several approaches to improving agricultural productivity and is a key to achieving global food security.

Crop land races are described as geographically or ecologically distinct populations that show conspicuous diversity in their genetic composition both among populations (land races) and within them (Brown, 1978). Rice genetic resource is the primary material for rice breeding and makes a concrete contribution to global wealth creation and food security (Zhang et al., 2011). Land races of rice can contain some valuable alleles not common in modern germplasm (Pervaiz et al., 2010).

Knowledge regarding the extent of genetic variation and genetic relationships between genotypes are vital for designing effecting breeding and conservation strategies (Roy et al., 2015). Characterization of germplasm is very important for identifying new genes and further useful for varietal identification. 

Rao et al. (2013) characterized sixty-five land races of rice for the establishment of the distinctness among land races and concluded that characterization would be useful for conservation of beneficial genes for getting protection under Protection of Plant Varieties and Farmer’s Rights Act. But, limited work has been done on characterization of local rice land races of Bangladesh. Therefore, systematic attempts have to be made to make a total inventory of this valuable gene pool for quantifying the availability of new useful genes of this resource. Besides, it is very important to protect bio-piracy and geographical indications and issues related IPR. The present experiment was, therefore, undertaken to study the qualitative agro-morphological characters of 40 similar or duplicate named Balam rice of Bangladesh.

Materials and Methods

The field experiment was conducted at Bangladesh Rice Research Institute (BRRI), Gazipur during T. Aman 2009 and T. Aman 2011 seasons. Forty land races of similar or duplicate named Balam rice germplasm of Bangladesh along with four popular varieties viz. BR7, BR16, BRRI dhan50 and Nizersail were characterized (Table 1). Single seedling of thirty days was transplanted using spacing within and between rows of 20 and 25 cm, respectively for each accession. The unit plot size for each accession was 4 rows, each of which was 2.7 m long. The fertilizers were applied at the rate of 60-50-40-10 kg NPKS per hectare.

Table 1 Alphabetical list of 40 Balam rice germplasms * = BRRI Rice Genebank accession number

The twenty-one qualitative agro-morphological characters were studied and recorded using “Procedure of DUS tests for inbreed and hybrid Rice” (as approved by National Seed Broad, Ministry of Agriculture in Bangladesh, 2001) and “UPOV Rice Test Guidelines” (sources: TG/16/8; project 3). According to Sneath and Sokal (1973), the qualitative data were converted to binary form. The presence and absence of the different variants scored as 1 and 0, respectively were estimated as described by Liu and Muse (2005) and by using Power Marker version 3.25 software. The cluster analysis was performed with the qualitative binary data as described by Rohlf (2002) and by using Numerical Taxonomy and Multivariate Analysis System (NTSYS-pc) version 2.2 software. For this, a similarity matrix was formed with Simqual subprogram by using the Dice coefficient. Then the cluster analysis was done with SAHN subprogram by using the unweighted pair group method on arithmetic mean (UPGMA) clustering method and finally the tree was made for showing the relationship among the genotypes. The principal coordinate analysis (PCoA) with the DCenter in NTSYS-pc was also performed with the matrix for estimating genetic distances.

Results and Discussion

Diversity of the phenotypes:

The similar or duplicate named Balam rice land races showed wide degree of diversity for different qualitative characters under studied. Only the penultimate leaf ligule characters (presence and shape) showed no variations among the genotypes, as because all the 40 genotypes had split or two-cleft shape type ligule. Earlier Hossain (2008) also reported similar result for green leaf color, presence of penultimate leaf ligule and two-cleft ligule shape on rice.

The unique Balam rice land races were found for different qualitative agro-morphological characters (Table 2), which could be used in hybridization programme regarding issues like distinctness of new variety and intellectual property right. The detailed phenotypic diversity of Balam rice land races for 19 qualitative agro-morphological characters are given below:

Table 2 List of unique Balam genotypes for different qualitative traits

Out of 40 similar or duplicate named Balam rice land races, 16 genotypes had the anthocyanin coloration in leaf sheath and the rest of the genotypes (60%) had no anthocyanin coloration (Figure 1). Among the colored genotypes, 9 had weak (3), 2 had medium (5), 3 had strong (7) (B17, B18 and B34) and 2 had very strong (9) (B9 and B16) color intensity. In total, 14 genotypes had green (2) color leaf blade, while 10 had pale green (1), 7 had dark green (3), 2 had had purple tip (4) (B5 and 26) and 7 had purple margin (5) (B9, B16, B17, B18, B34, B36 and B39) color leaf blade. Again for leaf, the maximum number of germplasm (16) had strong (7) surface pubescence on leaf blade, while the rest of 14 had medium (5), 8 had weak (3) and 2 had very weak or absent (1) pubescence (B12 and B33). However, the anthocyanin coloration of auricles and collar on penultimate leaf was present (9) only on 7 land races (B9, B16, B17, B18, B34, B38 and B39), while the rest (33) had no coloration (1). In total, 29 land races had colorless (1) ligule in penultimate leaf, while 3 had green with purple lines (3) (B20, B33 and B36) and 8 had light purple (4) color of ligule.

Figure 1 Distribution of leaf sheath color and its intensity, leaf blade color and its pubescence and auricle, collar and ligule color characters for 40 Balam rice land races

The 30 land races of Balam had white (1) color of stigma, while 4 had light purple (4) (B13, B20, B26 and B33) (Figure 2) and 6 had purple (5) color (B9, B16, B17, B18, B34 and B39). The maximum number of land races (33) had erect (<30⁰) type of flag leaf blade, while 3 of each had semi-erect (30-45⁰) and horizontal (46-90⁰) (B14, B20 and B24) and only B27 (Boislam) had descending (>90⁰) type of flag leaf. The main axes of 31 land races had erect (<30⁰) and the rest of 9 had intermediate (≈30Ëš) type stem curvature. For nodes anthocyanin color, only 10 land races of Balam rice had anthocyanin coloration in nodes (9), while the rest of the land races (30) had no coloration (1). Among the 10 colored land races, 7 had medium (5) and only 3 had very strong (9) intensity of anthocyanin colorations in nodes. They were B9 (Balam), B16 (Balam) and B34 (Lal Balam). However, the anthocyanin color intensity of internodes of 17 land races had weak (3), 16 had medium (5), 2 had strong (7) (B1 and B14) and 3 had very strong (9) (B9, B16 and B34). However, B31 (Kartik Balam) and B32 (Khud Balam) had very weak and B33 (Khud Balam) had medium intensity of anthocyanin coloration. Mahalingam et al. (2012) observed no variation for presence of leaf auricle and absence of anthocyanin coloration of nodes and Nascimento et al. (2011) for light green inter node in rice.

Figure 2 Distribution of stigma color, flag leaf attitude, stem curvature, node color and its intensity and internode color intensity characters for 40 Balam rice land races

The anthocyanin coloration of lemma and pale showed high degree of diversity among the land races (Figure 3). Out of 40 germplasm, 14 land races had yellowish to straw (1) color lemma and palea, while 11 had gold and or gold furrows on straw (2), 8 had brown spots/furrows on straw (3) and 5 had light purple on straw (6) color lemma and palea (Figure 4). However, only B22 (Beti Balam) and B26 (Boislam) had brown (tawny) (4) color of lemma and palea. Besides, 18 land races of Balam had medium (5) intensity of anthocyanin coloration on lemma and palea, while 17 had strong (7), 3 had very strong (9) (B1, B3 and B19), 1 of both had very weak (1) (B10) and weak (3) (B38) intensity. On the other hand, a total of 16 land races showed yellowish/straw (2) color, while 10 showed gold (3), 7 showed purple apex (8), 5 showed brown (4) and 2 showed purple (7) (B16 and B39) color of apiculus. In case of awn, 35 land races had awnless (1), whereas only 9 land races had awn on grain (9). Among the 9 awned grain land races, only B5 had awn throughout the whole length of panicle (9), 3 had awn on the tip of panicle only (1) (B1, B4 and B13) and only B8 had awn on upper half of panicle (5). Again, 3 land races showed yellowish white to straw (1) color awn (B4, B8 and B13) and 2 showed brown (3) color awn (B1 and B5). The leaf senescence of 23 land races of Balam rice had intermediate (5) and 17 had late and slow (1) leaf senescence at the time of maturity.

Figure 3 Grain diversity of Balam rice land races of Bangladesh

Figure 4 Distribution of qualitative characters (color of lemma and palea and its intensity, apiculus color, awn distribution and its color and leaf senescence) for 40 Balam rice land races

Distribution of the phenotypes

In the present study, 24 land races (60%) of similar or duplicate named Balam rice showed no anthocyanin color in leaf sheath and basal leaf sheath, 14 (35%) had green leaf blade color, 16 (40%) had strong surface pubescence of penultimate leaf blade, 33 (82%) showed colorless auricles and collar  and 29 (72%) had colorless ligule in penultimate leaf, 30 (75%) had white color of stigma, 33 (82%) showed erect blade of flag leaf, 31 (77%) had erect curvature of lateral tiller, 30 (75%) showed no anthocyanin color in nodes and 7 (17%) showed its medium intensity, 17 (42%) had weak intensity of anthocyanin color in internodes, 14 (35%) showed yellowish to straw anthocyanin color of lemma and palea (below apex area) and 18 had its medium intensity (45%), 16 (40%) showed yellowish/straw color of apiculus, 35 (87%) had awnless grain and 3 (7%) had awns at tip only  with yellowish white to straw coloration and 23 (58%) showed intermediate type of leaf senescence (Figure 5). Nascimento et al. (2011) found white color of stigma and presence of the glumella pubescence as dominant types in 146 accessions of upland rice. Parikh et al. (2012) also observed majority of the genotypes to possess green basal leaf sheath color (84.5%), green leaf blade color (86.8%), green tip color (57.8%), green leaf margin color (57.8%), green collar color (97.3%), white ligule color (94.7%), light green auricle color (97.3%), semi erect plant habit (44.7%), white apiculus color (53.9%), white stigma color (94.7%), awnless (72.3%) and white sterile glume color (59.2%) in 71 aromatic rice germplasm.

Figure 5 Distribution (%) of major qualitative characters of 40 Balam rice land races

Clustering of the phenotypes

A dendrogram was constructed by using UPGMA clustering method based on Dice coefficient across the 40 land races along with four popular varieties. The cluster analysis grouped the land races into four clusters for 19 qualitative agro-morphological characters (Figure 6). Cluster III was the major one with maximum land races (30), while clusters I consisted of three (B20, B33 and B26), cluster II of seven (B9, B34, B16, B17, B18, B39 and B38) and cluster IV of four (B1, B40, B5 and B13) land races. Again, Clusters III had three sub-clusters. The first sub-cluster consisted with sixteen land races namely B2, B35, B30, B23, B7, B29, B28, B37, B31, B32, B8, B21, B24, B25, B27 and B36 along with the popular varieties BR7, BR16, BRRI dhan50 and Nizersail. The second sub-cluster had six land races namely B3, B11, B12, B22, B10 and B4. The third sub-cluster consisted with four land races namely B6, B15, B14 and B19. Rahman et al. (2009) studied 110 rice varieties for evaluating genetic divergence and identified four groups for the qualitative data studied. But, Nascimento et al. (2011) found two major groups by using UPGMA clustering method in 146 accessions of upland rice.

Figure 6 Dendrogram of 40 Balam rice for 19 qualitative agro-morphological characters

It also revealed that B7 (acc. no. 853) and B23 (acc. no. 878) were found duplicate (100% similar) for all the characters studied (Figure 2). Besides, BR7 and BRRI dhan50 were also found duplicate. Earlier, Bisne and Sarawgi (2008) and Nascimento et al. (2011) also found duplicates by studying qualitative characters in rice accessions. But none of these duplicates were included in accession list with the same genotype name. Whereas, Hossain (2008) found duplicates for qualitative traits in aromatic and fine grain land races of rice and three pairs of these duplicates (Kalijira-1 & Kalijira-2, Kalijira-8 & Kalijira-10, Kalijira-12 & Kalijira-14) were included in accession list with same name. On the other hand, Fukuoka et al. (2006) reported that significant variation may be found among genotypes with the same name. However, the highest genetic distance (9.995) was recorded between genotype B22 and B31.

8 Conclusion

The variability and unique feature of Balam rice with diversified gene pool could be utilized for developing varieties and thus broaden the genetic base of the modern rice. Many studied land races had strong hairs on the surface of the penultimate leaf blade and might be resistance/tolerance to leaf surface related insects and diseases infestation. Molecular characterization of the identified land races need to be done for QTL mapping.

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