No abstract

An experiment was conducted with 55 rice varieties to assess the genetic diversity by using Mahalanobis D2 Statistical and characterization of genotypes using principal component analysis. All genotypes exhibited a wide and significant variation for 19 traits, by cluster analysis grouped into ten clusters. The maximum genotypes were included in Cluster 6 (16) followed by cluster 4 (10), cluster 3 (8), cluster 2 (7), cluster 5 (5), cluster 8 (4), cluster 1 (2), with 29.09, 18.18, 14.54, 12.72, 9.09, 7.27 and 3.63 proportion respectively, the rest of three clusters had one genotype each. Maximum cluster distance obtained between cluster×constituted by single entry (Pusa Basmati) showed highest inter cluster distance from cluster V (20727.37), VII (18414.79), I (17228.89) and cluster III (17010.24) are having very high inter cluster distance and also by cluster IX from cluster VIII (8852.36), VI (7559.67), I (7444.68) and cluster VII (6666.83) followed by cluster VI from cluster V (6225.95). The lowest inter cluster distance was observed between cluster II and cluster IV III and VI followed by between cluster I and cluster VIII, XI, II, VI and cluster IV. The intra cluster D2 values ranged from Zero (Cluster VII, IX, X) to 2233.91 (Cluster VIII). Contribution of amylose content was highest towards genetic divergence (23.43%) by taking 348 times ranked first followed by days to 50% flowering (23.37%) by 347 times, single plant yield (23.3%) by 346 times. The PCA analysis showed that first eight principal components accounted for about 85.4%.

During the recent field survey it was found that among 15 rare mangroves in Andaman and Nicobar Islands, ten rare species i.e. Acanthus ebracteatus, Acrostichum speciosum, Bruguiera cylindrica, Cynometra iripa, Cynometra ramiflora, Lumnitzera racemosa, Rhizophora hybrids, Sonneratia alba, Sonneratia griffithii and Xylocarpus mekongensis are present in Andaman and Nicobar islands. In addition to Acanthus volubilis, Brownlowia tersa and Sonneratia ovata are recorded after their first report.

Rhizophora mucronata var. alokii (Rhizophoraceae), a new variety of Rhizophora from the Andaman and Nicobar Islands, India, is described and illustrated. The new variety is remarkable in having four stamens, laterally folded leaves, a short peduncle, thick leathery petals, and a four-sided ovary with a sessile style. A key for the species of Rhizophora of the Andaman and Nicobar Islands is also provided.

Ragavan P, Ravichandran K, Mohan PM, Sxaena A, Prasanth R S, Jayaraj RSC, Saravanan S. 2014. New distributional records of Sonneratia spp. from Andaman and Nicobar Islands,. Sonneratia lanceolata, Sonneratia x urama and Sonneratia x gulngai was collected from Great Nicobar Island, which representing a new addition to the mangrove flora of India. S. lanceolata is distinguished from S. caseolaris by its drooping branches, lanceolate leaves and ovoidal bud without medial constriction. S. x urama and S. x gulngai are putative hybrids. S. x urama is putative hybrid between S. alba and S. lanceolata, whereas S. x gulngai is putative hybrid between S. alba and S. caseolaris. A detailed description along with colour plate and relevant notes is provided for further collection and identification of these species in the field.