Morphological and hormonal studies on submergence tolerance during germination and seedling establishment of rice (Oryza sativa) genotypes with AG, SUB1, and combined AG and SUB1 traits

Date

2011

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Maribel L. Dionisio-Sese

Co-adviser

Abdelbagi M. Ismail

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Abstract

Submergence is one major concern in rice production since many lowland rice farms are severely affected by heavy rains. Plant breeders have recently identified rice genotypes with AG trait required for tolerance of flooding at germination and early seedling stage, and Sub1 trait required for tolerance of complete submergence at the vegetative stage. Four rice genotypes, each representing one of the following genotype groups – AG-containing (Khap Hlan On; KHO), Sub1-containing (Swarna-Sub1), AG+Sub1-containing (IR83370-9-3-2-23), and non-AG non-Sub1 (IR42) – were studied under hypoxic laboratory and flooded greenhouse conditions for morphological and hormonal responses during submergence. Under laboratory condition, rice genotype with combined AG+Sub1trait, IR83370-9-3-2-23, in comparison with the intolerant (non-AG non-Sub1) genotype, IR42, showed higher germination rate and coleoptile length, similar to the AG genotype, KHO. Under greenhouse condition, IR83370-9-3-2-23 responded similarly to Sub1 genotype, Swarna-Sub1. Restriction of shoot growth in both IR83370- 9-3-2-23 and Swarna-Sub1 lines during complete submergence for 14 days was observed, allowing them to maintain reserves for re-growth when water recedes. On the other hand, intolerant non-Sub1 genotypes, IR42 and KHO, had significant shoot elongation during complete submergence, hence, the shoot lodged when water receded and eventually died. Variations in hormone levels under hypoxic conditions seem to have an effect on the degree of tolerance to anaerobic germination and complete submergence.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Document Type

Thesis

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