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Suralta R.R.,Nagoya University | Suralta R.R.,Philippine Rice Research Institute PhilRice | Kano-Nakata M.,Nagoya University | Niones J.M.,PhilRice | And 6 more authors.
Field Crops Research | Year: 2016

Roots play a number of important roles in crop adaptation to various abiotic stresses such as water stress. However, traits responsible for such adaptation may differ with environments. This paper reviews recent progress in our research on the functional roles of important root traits. We have been paying special attention to drought as well as to soil moisture fluctuations as prevailing water stresses, and the ability of the plant to change its development as environmental conditions change, which is known as phenotypic plasticity. We have been using various rice accessions/mapping populations such as the OryzaSNP panel, chromosome segment substitution lines (CSSL) derived from a Nipponbare and Kasalath cross, and IR64 introgression lines. The results consistently showed that, in addition to deep roots, the plasticity of root system development is a key trait for plant adaptation to water stress. We found that plasticity in the development of the entire root system as a function of the plasticity in lateral root development is important under progressive drought, while plasticity in lateral root development that is associated with aerenchyma formation is important under transient drought-to-waterlogged conditions. We quantitatively showed the contributions of root plasticity to dry matter production and yield through enhanced water uptake under such water stress. We also identified quantitative trait loci (QTLs) that are responsible for root plasticity. The importance of explicitly characterizing the nature of the stresses in the target areas is discussed in relation with designing an ideal root system, which is a primary requirement to define an actual breeding target for improving productivity in abiotic stress-prone soil environments. © 2016 Elsevier B.V.

Orge R.F.,Philippine Rice Research Institute PhilRice | McHenry M.P.,Murdoch University
International Journal of Innovation and Sustainable Development | Year: 2013

Successful long-term domestic rice research to feed the rapidly increasing population in the Philippines facilitated increased production of the nation's staple from 11.786 MT in 1999 to 16.258 MT in 2008. The additional rice production has correspondingly increased the annual milled rice husk waste resource to around 3.4 MT - currently, a disposal problem for millers who often dump the waste in open fields to slowly decompose. The waste represents approximately 42 million GJ of energy, equivalent to 7 million barrels of oil. This paper discusses the local development of an inexpensive, simple, fast, safe and versatile continuous rice husk carboniser which overcomes many limitations of existing batch carbonisers, including unacceptable operator emission exposures. The small-scale, portable, motor-less carboniser was designed to allow retrofitting of heat recovery components for alternative applications, including crop drying, and steam-driven systems, such as water pumps, as co-products to biochar used locally as a fertiliser. Copyright © 2013 Inderscience Enterprises Ltd.

Vu H.T.T.,Kobe University | Vu H.T.T.,Agricultural Genetics Institute AGI | Manangkil O.E.,Kobe University | Manangkil O.E.,Philippine Rice Research Institute PhilRice | And 3 more authors.
Biotechnology and Biotechnological Equipment | Year: 2012

Elongation escape mediated by seedling vigor with fast shoot elongation under submergence is considered to be an important strategy for rice particularly in direct seeding cultivation systems. We compared the expression profiles of two key genes in rice for ethylene biosynthesis - 1-aminocyclopropane-1-carboxylate synthase (OsACS) and oxidase (OsACO) genes, and five Na+/H+ exchanger (OsNHX) paralogs under normal and submerged conditions. The amount of transcripts was studied by RT-PCR using seedlings of one japonica and three indica cultivars with different levels of seedling vigor under submergence. In both types, submergence induced marked accumulation of transcripts of all paralogs of OsACS and OsACO except for OsACS1, which showed complete repression under the stress in non-vigorous indica cultivars suggesting its key role in seedling vigor under submergence. OsNHX expression was also enhanced under submergence, and the levels of OsNHX1 and OsNHX5 transcripts agreed well with those of seedling vigor under submergence. The observed mode of OsACS, OsACO and OsNHX expression under submergence suggests that these genes can be potential targets for understanding the mechanism regulating seedling vigor under submergence at the post-germination stage in rice. © 2012 American Scientific Publishers.

Bautista E.G.,Philippine Rice Research Institute PhilRice | Saito M.,Tohoku University | Regalado M.J.C.,Philippine Rice Research Institute
Journal of Food, Agriculture and Environment | Year: 2014

In the Philippines, the tremendous quantity of rice husks (RH) produced by rice millers poses a variety of potentially harmful consequences to humans and the environment. We evaluated the burning of RH in updraft gasification systems to ameliorate the problem of RH disposal and reduce the use of other sources of energy that are usually purchased. In 2008, to assess the handling of rice by Philippine millers, we conducted a survey to determine the number and characteristics of rice milling factories in Central Luzon, specifically in Nueva Ecija, which is among the top rice-producing provinces. In this study, we focus on the most prevalent size of factory, which uses a single-pass mill with an average capacity of 1 t h-1 and requires roughly 30 kW of electric power, as the type of operation that would benefit by employing was targeted to be powered by a rice husk (RH) gasification system as a source of power. We evaluated the performance of such a system that is installed at the Philippine Rice Research Institute (PhilRice). This system comprises a gasifier reactor (internal volume, 1.44 m3), scrubber, condensers, filter, gas storage unit, and an internal combustion engine coupled to an electric generator. The gasification temperature ranged from 703 to 837°C, and the average temperature of the gas entering the engine was 39°C. The conversion rate from raw RH to carbonized rice husk was 18% by weight. On average, the system generated 10-18 kW at 173-240 V, based on a RH consumption rate of 78 kg h-1. Our results show that the generated power is insufficient to operate a rice mill processing 1 t h-1, but assessment of the operation indicates that this type of gasification system may be technically feasible if modified. The current size of the reactor and rate of RH consumption could produce 30 kW, if the efficiency of the engine and electric generator was improved. Given these improvements, RH updraft gasification systems might provide the electricity needed for local milling factories, using 40% of the RH material produced during milling operations.

Beltran J.C.,University of Western Australia | Beltran J.C.,Philippine Rice Research Institute PhilRice | Pannell D.J.,University of Western Australia | Doole G.J.,University of Western Australia | Doole G.J.,University of Waikato
Crop Protection | Year: 2012

Implications of increasing labour costs and the development of herbicide resistance for profitable weed management in Philippine rice farming systems are investigated. The study employs RIMPhil (Resistance and Integrated Management in the Philippines), a bioeconomic simulation model developed to provide a comprehensive assessment of integrated weed management programmes for the control of annual barnyardgrass (Echinochloa crus-galli) in rice crops. Results indicate that herbicide application will become increasingly economically attractive, relative to manual weeding, as labour cost increases. This is important since urban migration in the Philippines continues to increase the scarcity of rural labour. Results also show that the onset of herbicide resistance results in substantial losses in farm profit. It is worthwhile for farmers to take management actions to prevent or delay the onset of herbicide resistance, provided that these changes are effective and not too costly. The study highlights the complexity of decision making about integrated weed management on rice farms in the Philippines. © 2011 Elsevier Ltd.

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