Growth Responses of Seedlings in Oryza glaberrima Steud. to Short-term Submergence in Guinea, West Africa

Abstract

In inundation areas in rainfed lowland and inland valleys of Guinea as well as other regions in Africa, submergence for a few days to a few weeks with a water depth less than 50 cm occurs in rice cultivation during the rainy season. Young rice seedlings after transplanting are particularly vulnerable to submergence stress. Oryza glaberrima Steud. is well adapted to growth in inundation areas with deepwater conditions in West Africa; however, it is not evident whether it resists short-term submergence stress after transplanting. The purpose of the study was to understand the physiological responses of rice plants after transplanting to short-term submergence stress under rainfed conditions for O. glaberrima by comparison with several genotypes of Oryza sativa L. from Guinea. Eight genotypes of O. glaber rima and seven genotypes of O. sativa including two shoot elongation genotypes, one submergence tolerant genotype as a control cultivars, and four genotypes of common cultivars in West Africa were used. Thirty day-old seedlings were submerged completely for 10 days with medium deepwater conditions at 45 cm water depth at 13 days after transplanting in a lowland field. O. glaberrima showed higher shoot elongation ability during submergence than any genotype of O. sativa that we tested. However, O. gla berrima lodged easily after desubmergence due to longer and rapid shoot elongation during submergence, and thus triggered a decrease in its survival rate. The submergence tolerant genotype of O. sativa maintained the dry matter weight of the leaf blade during submergence through the inhibition of shoot elongation. We suggest that O. glaberrima is susceptible to short-term submergence while it may adapt to prolonged flooding because of improved restoration of aerial photosynthesis and survival rate through shoot elongation ability.Discipline: Crop production Additional key words: anaerobic conditions, dry matter, leaf expansion, shoot elongation, survival JARQ 42 (3), 157 -162 (2008) http://www.jircas.affrc.go.jp This paper reports the results obtained in the joint project on "Improvement of water stress resistance in rainfed rice in

Identification of rice genotypes tolerant to submergence at seedling stage in Uganda

“…MET 15 Strong-S stage of rice (Joho et al, 2008). Internodes elongation was observed in the CG 14 variety, which measured 5 to 8 cm; moreover, CG 14 is an early maturity variety and it has been reported by Datta (1980) that, early-maturing varieties show relatively vigorous elongation capacity in the early vegetative growth phases.…”

“…An experiment was conducted at National Crop Resources Research Institute (NaCRRI) -Namulonge-Uganda. Rice genotypes were evaluated under controlled flood condition in both screen house and under field condition according to Joho et al (2008). Nursery bed was prepared, where seeds of 29 cultivars were sown separately in soil (3 seeds per hole).…”

Submergence Tolerance of Rice Species, Oryza glaberrima Steudel

“…The flooding response of O. glaberrima should be discussed thoroughly, but it is not clear from Futakuchi's report (2001) (Joho et al, 2008). In fact, O. glaberrima showed higher shoot elongation ability during submergence than any genotype of O. sativa that we tested.…”

“…Escape strategies based on elongation by stem or leaves are prominent characteristics of deep-water and floating rice. However, rapid elongation by leaves of young plants in response to short-term submergence flash flood (for up to 2 weeks) adversely affects tolerance by depleting carbohydrates that would otherwise support survival during and after submergence (Chaturvedi et al, 1995;Setter & Laureles, 1996;Kawano et al, 2002;Ram et al, 2002: Jackson & Ram, 2003Joho et al, 2008). The submergence tolerance gene, Sub-1A, depresses shoot elongation under short-term submergence to ensure survival.…”

Variation and Phenotypic Evaluation of Intraspecific Oryza glaberrima Lines Resulting from Crossings between Tog5681, Tog5672 and Tog7291

“…Recent findings by AfricaRice scientists and their partners, especially breeders, agronomists and nutritionists, have sparked renewed interest in the cultivated African rice species O. glaberrima (Sarla, 2005;Joho et al, 2008;Futakuchi & Sié, 2009;Mohapatra, 2010Mohapatra, , 2011Moukoumbi et al, 2011). Indeed, O. glaberrima has proved to be a rich source of resistance genes for rice production constraints in West and Central Africa (WCA), e.g.…”