MSc

ABSTRACT
Genetic diversity in rice, one of the most ancient and major food crop of the world, far exceeds that in any other crop. The present study on “Characterization of exotic germplasm of rice (Oryza sativa L.) for yield and quality attributes” was done in the Department of Plant Breeding and Genetics, College of Horticulture, and at the experimental farm of NBPGR Regional station, Thrissur, during June 2019 to October 2019. Hundred exotic accessions of rice received from IRRI, Philippines were evaluated along with five checks varieties viz., PTB 39 (Jyothi), Jaya, Thulasi, PTB 60 (Vaisakh) and Manurathna. The experiment was set in augmented block design with 5 blocks; each block comprising of 20 exotic accessions and five check varieties. Each entry was planted in plots of 5m2 at a spacing of 15 x 20 cm2. Out of hundred accessions, eighty-nine germinated and were evaluated for qualitative and quantitative traits at appropriate stages as per DUS descriptor (2006).
Out of the 25 qualitative traits observed, eight each were monomorphic and dimorphic. The traits flag leaf attitude, lemma and palea colour, colour of apiculus, distribution of awns, panicle attitude of main axis, panicle exsertion, and pericarp colour were found to be trimorphic. Colour of awns and caryopsis shape had four classes. Qualitative traits were less affected by the environment and they can be used as robust morphological markers for identifying genotypes. Twenty-two accessions were identified as superior with erect leaf, erect flag leaf, erect and strong culm and well exserted panicle.
Based on qualitative characters accessions grouped into 12 clusters. Thirty-five accessions belonged to the first cluster. Cluster 3 comprised 25 accessions, Cluster 9 and 11 consisted of 11 accessions each. Second cluster included two accessions, while cluster 10 had three accessions. Other six clusters were composed of single accessions.
Observation on quantitative characters showed that seventeen accessions were having low height than the check varieties. Thirty-six accessions were having longer ligule, while, fifteen accessions were having longer leaf and accession EC 204863 had broader leaves. Thirty-three accessions were early to flower and 34 accessions were
early to mature. Accessions EC 207747, EC 204863, EC 205042 and EC 205128 had high number of tillers. Accessions EC 207747, EC 204863, EC 205070 and EC 415401 had high number of productive tillers per plant. Accessions EC 204847, EC 205001, EC 205223, EC 205314, EC 415448 and EC 415452 had more number of spikelets. While, comparing with check varieties, eighteen accessions had longer panicles. Eight accessions had more grain number and nineteen accessions had longer grains. Majority of the accessions had grain yield on par with check varieties.
Correlation studies showed that plant height had positive correlation with leaf length and width, number of total and productive tillers, panicle length and grain width. Correlation of ligule length with leaf length and grain width was negative. Leaf length was correlated with leaf width, number of total tillers and grain width. Leaf width exhibited positive association with plant height, length of leaf blade, number of total tillers, hundred seed weight, panicle length and grain width. Days to fifty per cent flowering expressed negative association with test weight. Total number of tillers was positively associated with plant height, length and breadth of leaf, number of productive tillers, panicle length and grain width, whereas, it was negatively correlated with grain length. Number of spikelets per panicle had positive correlation with grains per panicle and negative association with grain length. Positive and significant association was observed between 100 grain weight and grain yield.
Dendrogram constructed using average linkage distance resulted in four clusters with majority of the accessions falling in the cluster 1.
Accessions EC 207747, EC 204970, EC 204999, EC 205042, EC 205047, EC
205192, EC 2052015, EC 205223, EC 205333, EC 415392, EC 415403, EC 415407,
EC 415413, EC 415420, EC415421, EC 415422, EC 415445, EC 415452 were
identified as superior when quantitative and qualitative traits considered together and these exotic accessions can be used in breeding programmes after further confirmation studies.