CHARACTERISING UPLAND RICE LANDRACES FROM THE NORTH- WESTERN REGION OF SARAWAK

Zazevia, Frank Clifton (2024) CHARACTERISING UPLAND RICE LANDRACES FROM THE NORTH- WESTERN REGION OF SARAWAK. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

Oryza sativa L. or commonly known as rice belongs to the family of Poaceae. In Malaysia, rice is normally cultivated either as lowland or upland rice. Commonly, upland rice is cultivated for domestic consumption in Sarawak. There has been no prior documentation of upland rice in Sarawak. It has many good characteristics including colourful grain and good fragrance. In this study, 22 upland rice accessions from the North-Western region of Sarawak were characterised. The present study was undertaken with the objectives to characterised morphological traits, anatomical traits, as well as genetic diversity using Simple Sequence Repeat (SSR) marker and matK barcoding gene. A total of ten accessions were further selected at S1 generation and the morphological traits were characterised. The qualitative traits observed on the first generation of 22 upland rice accessions viz., blade colour, ligule colour, auricle colour, panicle type and grain colour while the quantitative traits viz., heading days (94-126 days), flowering days (127-153 days), culm length (40.7 – 115.7 cm), tiller number (2-6 tillers), panicle number (1- 7 panicles), and percentage of filled grain (40-90%) were useful for characterisation as they exhibited variations. There was a positive correlation between the percentage of filled grains with the number of panicle and number of tillers. Due to certain constraint, only selected morphological traits were observed and leaf anatomy was done for accessions in S1 generation. Qualitative trait such as blade colour and ligule colour, while quantitative traits viz., plant height (p <0.01), culm length (p <0.01) and number of tillers (p < 0.01) were found exhibited variations between the accessions in S1 generation. The leaf, midrib and root anatomy of the accessions in first generation and S1 generation have the same fundamental anatomical structure. Leaf anatomy revealed that all the accessions contained silica body, which may correlate with resistance to fungal diseases and insect pests. There was no variation in terms of cell arrangement in leaves, midrib, and root of both first and S1 generation. A total of 39 SSR markers distributed across the 12 chromosomes were screened for polymorphism. A set of eight SSR primer pairs were polymorphic. A total of 18 alleles were detected across the 22 upland rice accessions, with an average of 2.57 alleles per SSR marker. Number of effective alleles was 1.64 in the present study. The average of polymorphism information content value was 0.67, which revealed that the SSR markers used in this study were highly informative. It is concluded that the studied accessions were low in diversity based on the value of Nei’s gene diversity and Shannon’s Information Index. A dendrogram was constructed using UPGMA analysis and revealed the clustering of accessions into two clusters. The clustering analysis did not show clear clustering of 22 upland rice accessions according to their morphological traits nor geographical origin. Barcoding gene marker matK revealed the accessions could be assigned to one clade along with the 22 lowland rice accessions from UNIMAS collection. Also in the cluster were 94 rice accessions from different origins and three accessions of Oryza rufipogon. The clustering categorise the accessions based on their matK sequence. In conclusion, this study observes the variations of Sarawak upland rice. A set of collection at S1 generation is now available for further characterisation and may become breeding lines to improve the quality and yield of Sarawak upland rice. Keywords: Sarawak, upland rice, morphological, anatomical, microsatellite, matK

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