Effect of AG1 and AG2 QTLs and combination of crop management on establishment, physiology, antioxidant properties, yield and grain quality of direct-seeded rice during anaerobic germination / Satyen Mondal ; Pompe C. Sta. Cruz, chair, guidance committee ; Abdelbagi M. Ismail, co-chair, advisory committee.

Date

12-2017

Abstract

Anaerobic condition caused by flooding during germination in direct-seeded rice (DSR) systems, known as anaerobic germination (AG), severely reduces crop establishment in both rainfed and irrigated areas. This study was conducted to quantify the effect of incorporating two major QTLS, AGI and AG2, associated with tolerance to flooding during germination; and to assess their interactive effect on enhancing crop establishment, as well as yield, yield attributes and grain quality. A greenhouse and three field experiments were conducted at the International Rice Research Institute (IRRI), Los Bañas, Philippines, using elite lines incorporating AGI, AG2 and AGI-AG2 in the background of the popular varieties PSB Rc82 (PSB Rc82-AG1, PSB Rc82-AG2, PSB Rc82-AG1-AG2) and Ciherang-Sub1 (Ciherang-Sub1-AG1, Ciherang-Subl- AG2, Ciherang-Sub1-AG1-AG2), along with the AG tolerant donors Kho Hlan On (for AGI) and Ma-Zhan Red (AG2) and the recipients PSB Rc82 and Ciherang-Subl. The greenhouse experiment was conducted using concrete tanks with 10 cm water depth and field experiments were under DSR system with flooding of 3-5 cm water depth. Flooding reduced overall seedling survival both in greenhouse and field conditions, though survival of AG1-AG2 introgression lines was greater than other genotypes. Soluble sugars increased, while starch concentration decreased gradually under flooding especially in the tolerant checks and AGI-AG2 introgression lines. Less lipid peroxidation and higher amylase activity, reduced-ascorbate (RAsA), and total phenolic contents (TPC) were observed in the tolerant checks and in AGI-AG2 introgression lines. Lipid peroxidation was negatively correlated with ascorbate, and total phenolic concentrations and reactively correlated with reactive oxygen species (ROS). Introgression of AG1-AG2 QTLs upregulated total amylase activity causing rapid starch degradation and increase in ascorbate and total phenolic concentrations, resulting in higher germination and seedling growth in flooded soils. The AG lines had 2-3 fold higher grain and biological yield than the sensitive checks under flooding stress during germination and early growth stage. The values of physical and chemical grain qualities of six AG lines were similar with their recurrent parents. Seed pre-treatments, like hydro-priming and pre-soaking for 24 h significantly improved germination rate, survival percentage, and overall, increased tolerance to flooding of rice genotypes. Lower seed rate (4 g m-2) with shallow burial depth (0.5 cm) resulted in better seedling establishment following flooding in DSR system. Introgression of AG QTLs did not have any negative impact under control (non-flooded) and flooded conditions with respect to seed physiology, survival, growth, biomass production, phenology, yield, and grain quality.

Document Type

Dissertation

Degree

Doctor of Philosophy in Agronomy

College

Graduate School (GS)

Adviser/Committee Chair

Pompe C. Sta. Cruz

Committee Member

Shalabh Dixit, Nina M. Cadiz, Constancio C. De Guzman, Abdelbagi M. Ismail, Pompe C. Sta, Cruz

Language

English

LC Subject

Rice -- Preharvest sprouting, Rice -- Seedlings -- Effect of floods on, Crop improvement -- Research, Rice -- Hybridization, Agronomy Institute of Crop Science

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 996 2017 A42 M66

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