Genetic Divergence in IndigenousWild and Cultivated Rice Species of Manipur Valley

Genetic divergence of 32 indigenous rice germplasms and �ve wild rice of which three from Manipur and two wild rice procured from IRRI, Philippines was investigated usingMahalanobis,DD statistic. Based on twelve agromorphological characters, the thirtyseven germplasms both wild and cultivated were grouped into �ve clusters based on the relative magnitudes ofDD values following Tocher’s method of cluster formation. Based on the rank totals, the characters which contributed maximum towards genetic divergence in the present studies were grain yield/plant, spikelet/panicle, 100 grain weight, grain length, days to 50% �owering, ear bearing tillers/plant, and �ag leaf length. In the present study, maximum intercluster distance was estimated between cluster III and (󵀄󵀄DD2 = 14.09) which was closed followed by clusters II and V (󵀄󵀄DD2 = 12.50). On the basis of their greater intercluster distance, high value of cluster mean according to the character to be improved and performance of the individual germplasms for the character, the germplasms could be used in hybridization programme for improvement of different plant characters in the rice germplasms of Manipur.


Introduction
Manipur valley which is also considered as rice bowl of the state has a large variability of indigenous rice cultivars that belong to Asian cultivated rice O. sativa L. subspecies indica.So far, 44 indigenous rice cultivars along with two wild rice wainuchara one with perennial form and murshi another with annual weedy form have been recorded from Manipur valley by Singh and Sharma [1].If one considers the percentage availability of indigenous rice cultivar per unit area Manipur valley has one land race of rice per 42 sq⋅km.According to traditional classi�cation, more than 50 rice cultivars were cultivated in Manipur valley before the introduction of high-yielding varieties bred in Manipur.e high-yielding varieties of rice introduced from the plain or hill regions of the northern and southern parts of the country do not perform well in northeastern hill region [2].e importance of local land races of rice in breeding programme lies in the evolution of gene complexes in the local cultivars that have coadapted to speci�c local environment through long period of natural selection.ese gene complexes may not be readily reconstituted even by the modern recombinant DNA technology; we have to utilize the naturally occurring gene complexes for breeding of rice for speci�c local conditions.
e basic importance of genetic diversity in breeding for high yield has long been recognized as is evident from the results reported by several workers in different crops.e magnitude of heterosis in crop plants depends on the degree of genetic divergence between parental stocks and, consequently, may be used as an indicator of the inherent yielding capacity of a cross.While the importance of genetic diversity has long been appreciated by breeders, the basic difficulty has always been one of recognizing and estimating such diversity, shortness of actually making the cross.In view of the great importance of genetic diversity to breeding, techniques which can provide direct and reliable quantitative estimates of diversity at the genotypic level should prove to in this context that scientists, particularly the plant breeders of the state started giving their thought with all seriousness for the conservation of local rice germplasms.us, it is extremely important to study the genetic composition of the germplasms of existing modern day cultivars in comparison with their ancestors and related species.is will not only provide information on their phylogenetic relationship but also will indicate a chance of �nding new and useful genes, as the accessions with most distinct DNA pro�les are likely to contain a greater number of novel alleles.e use of Mahalanobis  2 statistics for estimating genetic divergence had been emphasized by many workers [4][5][6][7] because it permitted precise comparison among all possible pairs of population in any group before affecting actual crosses.In addition to aiding in the selection of divergent parents for hybridization,  2 statistics measures the degree of diversi�cation and determines the relative contribution of each component character to the total divergence [8].e utility of multivariate analysis in quantifying the degree of divergence between populations to understand the trend of evolutionary pattern, to assess the relative contribution of different components to the total divergence and to determine the nature of forces operating on inter-and intracluster levels has greatly been emphasized [9][10][11][12].Further, such studies have also permitted the choice of genetically divergent parents to obtain desirable recombinants in segregating generations [13].1.

Materials and Methods
ese germplasms were grown in the experimental farm of Manipur University, Manipur, India during kharif season of 2009 and 2010.e experiment was laid out in the research �eld of the University in the randomized block design with three replications.e interrow spacing was maintained at 20 cm.e recommended plant protection measures and agronomical practices were followed.e experimental data on various quantitative and qualitative characters were recorded as per criteria laid down in the standard Evaluation System for rice IRTP and "Descriptors for Rice" published jointly by International Rice Research Institute and International Board for plant Genetic Resources [14].Ten plants from middle three rows of each plot were randomly sampled and the quantitative characters were recorded following actual measurement on each of the sampled plants and then averaged it out.e qualitative traits were recorded through visual observation only.Nine qualitative traits were taken for the study.ey are leaf blade colour, leaf blade pubescence, basal leaf sheath colour, leaf angle, ligule colour, collar colour, auricle colour, �ag leaf angle, and ligule shape.e variables measured for quantitative characters were �ag leaf length, �ag leaf width, ligule length, culm diameter, panicle length, culm length, ear bearing tillers/plant, days to 50% �owering, grain length, 100 grain weight, spikelet/panicle, and grain yield/plant.e two-year data were pooled in the analysis.Mahalanobis  2 statistics was used to estimate genetic divergence among the thirty-seven germplasms.e germplasms were grouped into clusters according to Tocher's methods by Rao [15].

Results and Discussion
e thirty-seven rice germplasms both wild and cultivated were grouped into �ve clusters based on the relative magnitude of  2 values following the Tocher's method of cluster formation [15] with the criterion that the intracluster average  2 values should be less than the intercluster  2 values (Table 2).Maximum cultivars were in cluster I involving 25 out of 37 germplasms (Table 3).However, clusters IV and V had only one cultivar each.Average inter-and intra-cluster distances are presented in cluster diagram (Figure 1) and are also presented as a supplement of the table using    2 values of average inter-and intra-cluster.is depicted the genetic diversity in an easily understandable manner and provided information about relationships of different clusters.But the diagram presented was not exactly to the scale.e value of intracluster distance ranged from 0.00 (clusters IV and V) to 5.98 (cluster 1).It could be indicated that clusters I and III were highly divergent from clusters II, IV, and V.Moreover, cluster IV appeared less divergent from cluster II and cluster V to cluster III based on the values of intracluster distances.e average intercluster distance varied from 44.78 (clusters V and II) to 198.44 (clusters III and II).From the intercluster distances, it could be inferred that the cultivars belonging to clusters III and II (198.44) and clusters V and II (156.32) were more divergent and had a wide genetic variation than the others.
�lustering of thirty-seven germplasms with twenty-�ve germplasms into cluster I, six germplasms in cluster II, four germplasms in cluster III, and one germplasms each in clusters IV and V, each indicated presence of genetic diversity among the germplasms (Table 3).e random clustering pattern of germplasms from different valley districts of Manipur indicated that the genetic diversity of the germplasms is not necessarily related with the distribution of germplasms in different districts of Manipur valley.e genetic diversity among the germplasms in the present study may be resulted from genetic dri and selection that cause greater diversity than geographical distribution of Manipur valley as suggested by Murty and Arunachalan [4].Taothabi angouba (30) and Oryza nivara (37) maintained their separate identities by making monogenetic groups, that is, clusters IV and V while forming clusters.It might be due to its different genetic makeup from that of the other germplasms.

Average Inter-and Intra-Cluster Distances.
Maximum intercluster distance suggested wider diversity between the groups; while minimum intercluster distance indicated closer relationship by Singh et al. [16].Higher intracluster distance also indicated greater heterogeneity of the cultivars by Pattnaik [17].Genotypes belonging to different clusters separated by high estimated statistical distance could be used in hybridization programme for obtaining a wide spectrum of variation among the segregants [18].Further, the magnitude of heterosis largely depends upon the degree of genetic diversity in the parental lines Roy and Panwar [19].
In the present study, maximum intercluster distance was estimated between cluster III (   2 = 14.09), which was closely followed by cluster II, and V (   2 = 12.50).It is suggested that the crossing between the selected germplasms from clusters II and III or clusters II and V will give rise to high heterotic crosses and a wide spectrum of variation among the segregants.Since cluster 1 consisted of 25 germplasms with appreciably high value of intracluster distances, presence of high heterogeneity among the germplasms is expected.Hence, subclustering of cluster 1 is an approach towards the effective selection of desired parents for hybridisation programme within the cluster.e maximum inter-sub-clusters III and V which was closely followed by subclusters VIII and IX.e present �ndings indicated that, maximum intercluster distance was estimated between cluster III (   2 = 14.09) which was closely followed by clusters II and V (   2 = 12.50).It is s suggested that the crossing between the selected germplasms from clusters II and III or clusters II and V will give rise to high heterotic crosses and a wide spectrum of variation among the segregants.However, hybridization programme between the germplasms of cluster I, if considered necessary, crossing between the selected germplasms from the subcluster III and V or VIII and VII or III and VIII or III and VI is expected to give the satisfactory result.

Diversity in 12 Agronomic
e salient �ndings obtained from the present studies and their possible implications in the genetic improvement of indigenous and wild rice germplasms of Manipur are summarised hereunder.In the studies for genetic divergence of 37 rice germplasms, signi�cance of  2 values revealed the presence of considerable divergence among the genotypes.Based on the rank totals, the characters which contributed maximum towards genetic divergence in the present studies were grain yield/plant, spikelets/panicle, 100 grain weight, grain length, days to 50% �owering, ear bearing tillers/plant, and �ag leaf length.Clusters with the highest mean values of agronomic characters and best-performing germplasms within the cluster were identi�ed.Best performers for hybridisation were shown in Table 6.

Conclusion
Rice being the staple food crop of the people of Manipur, rice culture itself was associated with the history and culture of Manipur.As the state of Manipur is located in the Indo-China region, which is considered to be the primary centre of origin of rice, diverse forms of indigenous rice cultivars or land races including the wild forms are expected.e ��n��c� �f �n�eres�s e authors declare that they have no con�ict of interests.

T 1 :
Name of the genotypes included in the experiment.
T 5: Relative contributions of individual character towards divergence calculated under different methods.: In this method, the smallest contribution to the percentage rank total will be the highest contribution towards divergence.It is just opposite to other methods.is means that if the rank total increases, the percentage of contribution towards divergence decreases. NB Characters.Diversity in 12 agronomic characters of rice germplasms was shown in Table4.Considerable genetic diversity is observed in almost all the characters of the cultivars under study.3.3.2Analysis.e calculated values of  2 were tested against the tabulated values of  2 at 5% level of signi�cance for 12 degrees of freedom being much lower than minimum calculated values of  2 which obviously shows that  2 values were signi�cant.
T 6: Best performers for hybridization. of the presence of wild rice and diverse forms of wild rice O. ru�pogon local cultivar 1 "wainuchara" and annual weedy rice O. ru�pogon local cultivar 3 "murshi" and one land race per 42 sq⋅km area of Manipur valley.e future scope of the present investigation is to go further into the research and development work for improvement of indigenous rice germplasms of Manipur valley.Based on the present �ndings, breeding for various objectives in the indigenous rice cultivars of Manipur valley to be continued.Gene actions for various quantitative traits in the selected parents are to be investigated in order to adopt appropriate breeding techniques for production breeding programmes of local rice germplasms of Manipur.e above observations open up a new vista to the rice researchers of Manipur to obtain a �rsthand information regarding variability of rice germplasms and also to trace the phylogenetic relationship between the indigenous rice varieties and their wild progenitors through  2 analysis. expectations