International Rice Research Institute Research Articles

Imaginaries of Development: The Rockefeller Foundation and Rice Research

This article is both a historical and contemporary analysis of the Rockefeller Foundation's changing role in rice research over the past 50 years, and though there are many overlaps between them, focuses on three broad periods: first, the RF's early work in rice research, particularly through the establishment of the International Rice Research Institute (IRRI) and the Green Revolution era of the 1960s and 1970s; second, the development of the RF's rice biotechnology program in the 1980s; and third, the RF's focus on agricultural research in Africa, with rice research as a subset of their programmatic efforts, during the 1990s and beyond. Rice research in each of the different periods was driven by different framings of problems and potential solutions, incorporating wider ideologies, epistemologies, and key actors and networks, with the RF at the center. Viewed in this way, the Rockefeller Foundation's involvement in rice research cannot be seen ‘simply’ as an agricultural modernization project, but rather as simultaneously a sociopolitical project that extends particular modes of governance through homogenization and paternalism.

Design of throw-in type rice thresher for small scale farmers

Threshing is an integral part of postharvest activities for cereal and legume crops. In many developing countries, threshing is carried out manually by farmers that lead to low quality of paddy rice and grain loss. When the rice production increases, consequently the manual threshing becomes arduous. In order to mechanize this process, a throw-in type thresher JEP based on a prototype of a thresher made by IRRI (International Rice Research Institute) was designed and tested. The wind board was modified after testing to enhance threshing quality. Also, in place of welding the whole machine is joined by bolts, nuts and rivets for easy assembling and disassembling. Output capacity from the performance test on the machine was 316 kg/hr at a moisture content of 21%wb (wet base) for IR28 rice variety. This could attain 350-400 kg/hr when both, the speed and the feeding speed increase. The overall results are impressive and it will help improve drudgery and threshing challenges with small scale farmers. Keywords: paddy rice, postharvest, design, thresher JEP

Design of throw-in type rice thresher for small scale farmers

Threshing is an integral part of postharvest activities for cereal and legume crops. In many developing countries, threshing is carried out manually by farmers that lead to low quality of paddy rice and grain loss. When the rice production increases, consequently the manual threshing becomes arduous. In order to mechanize this process, a throw-in type thresher JEP based on a prototype of a thresher made by IRRI (International Rice Research Institute) was designed and tested. The wind board was modified after testing to enhance threshing quality. Also, in place of welding the whole machine is joined by bolts, nuts and rivets for easy assembling and disassembling. Output capacity from the performance test on the machine was 316 kg/hr at a moisture content of 21%wb (wet base) for IR28 rice variety. This could attain 350-400 kg/hr when both, the speed and the feeding speed increase. The overall results are impressive and it will help improve drudgery and threshing challenges with small scale farmers.

Development of introgression lines of an Indica-type rice variety, IR64, for unique agronomic traits and detection of the responsible chromosomal regions

A total of 334 introgression lines (INLs: BC 3-derived lines) derived from crosses between a recurrent parent of Indica rice cultivar IR64 and 10 donor parents, including new plant type (NPT) lines IR65600-87-2-2-3, IR65598-112-2, IR65564-2-2-3, IR69093-41-2-3-2, IR69125-25-3-1-1, Hoshiaoba, IR66215-44-2-3, IR68522-10-2-2, IR71195-AC1, and IR66750-6-2-1, have been developed. These INLs with IR64 genetic background were characterized for eight agronomic traits: days to heading, culm length, leaf width, leaf length, panicle length, panicle number, 100-grain weight, and total spikelet number per panicle at the International Rice Research Institute from 2005 to 2007. To identify introgressed segments from the donor parents, genotypes of the 334 INLs were detected using more than 200 polymorphic simple sequence repeat markers. These segments detected on chromosomes 1, 2, 4, 5, and 6 were commonly introgressed across the INLs from more than four donor varieties. Based on the data of phenotype and genotype for the 334 INLs, associations between agronomic traits and introgressed chromosomal segments in the 334 INLs were investigated. A total of 54 regions for the eight traits were detected: seven regions for days to heading, eight regions for culm length, eight regions for leaf width, four regions for leaf length, six regions for panicle length, three regions for panicle number per plant, seven regions for 100-grain weight, and 11 regions for total spikelet number per panicle. Among them, the region on the long arm of chromosome 4 was associated with characteristics of the NPT such as long leaf, broad leaf, and high spikelet number. The developed 334 INLs with the IR64 genetic background will be useful materials for genetic analysis of agronomic traits.

Phenol Accumulation in a Young Humic Fraction following Anaerobic Decomposition of Rice Crop Residues

Soil phenols have been implicated as inhibitors of soil N cycling within many agroecosystems, including irrigated lowland rice (Oryza sativa L.). To quantify the effects of crop management on temporal patterns of phenol accumulation in lowland rice soils, we measured phenol concentrations in two humic fractions at two crop growth stages in each growing season during a 4‐yr field study at the International Rice Research Institute (Philippines). Samples were collected from two double‐crop rotations (continuous rice and rice–maize [Zea mays L.]) with two N fertilizer rates (0 and nonlimiting), and with either aerobic or anaerobic decomposition of incorporated crop residues. Phenols were determined by tetramethylammonium hydroxide thermochemolysis. Compared with the other field treatments, anaerobic decomposition of crop residues with continuous rice and nonlimiting rates of N fertilizer promoted a gradual increase in the relative enrichment of phenols in the mobile humic acid fraction during the 4 yr. The level of enrichment varied among phenol compounds, developing the fastest and becoming most pronounced with the smaller molecules of molecular weight 168 or less. Anaerobic decomposition had less effect on phenol enrichment for continuous rice cropping without N fertilizer. No phenol enrichment was found with anaerobic decomposition of rice residues in the rice–maize rotation. Our results are consistent with previous findings of inhibited mineralization of humic N with anaerobic decomposition, continuous rice, and nonlimiting rates of N fertilizer. Rotation of maize with rice or other techniques to ensure aerobic decomposition of crop residues may help mitigate or prevent phenol accumulation.

Grain number and grain weight in wheat lines contrasting for stem water soluble carbohydrate concentration

In wheat, the ability to store and remobilise large amounts of stem water soluble carbohydrates (WSC) to grain constitutes a desirable trait to incorporate into germplasm targeted to regions with frequent terminal drought. The main aim of this paper was to examine the relationships between WSC storage, grain number and grain weight across several environments. A small set of recombinant inbred lines (2–4) contrasting in stem WSC were grown in six field trials where water availability, sowing date and/or N level were manipulated, with line yields ranging from 400 to 850 g m −2 across experiments. Biomass, N and WSC concentration (WSCc, mg g −1 dry weight) and amount (WSCa, g m −2) were monitored. A resource-oriented area-based model [Fischer, R.A., 1984. Growth and yield of wheat. In: Smith, W.H., Bante, S.J. (Eds.), Potential Productivity of Field Crops Under Different Environments. International Rice Research Institute, Los Baños, pp. 129–154] and intrinsic rates of organ growth were used to investigate the consequences on grain number of potential competition between spike and stem around flowering. Early sown irrigated trials allowed consistent genotypic discrimination for WSCc and WSCa. High WSC lines had similar or higher yields compared to low WSC lines. High WSC lines had consistently lower grain number m −2 linked to a lower number of spikes and stems m −2, higher individual grain weight under irrigated or more limited conditions, and individual stems with less structural biomass. The changes in plant type associated with the high WSC phenotype, mainly fewer stems and a high individual grain weight, may contribute to its moderate yield advantage despite the lower grain number m −2. A model based on resource capture per unit area around flowering was not sufficient alone to explain the differences between lines in grain number m −2. We propose that linking a resource-based model with additional understanding of controls of crop morphology would improve the prediction of differences in yield components in related genetic material.

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Aerobic rice: crop performance and water use efficiency

Rice (Oryza sativa) production largely depends on traditional flooded rice systems whose sustainability is threatened by a progressive decrease in water availability and a constant increase in rice demand due to strong demographic boom in world population. A newly developed water-saving rice system is aerobic rice in which rice grows in nonflooded and unsaturated soil. From 2001, at the International Rice Research Institute in the Philippines, this system has been monitored to identify potentially promising varieties of rice able to grow as an irrigated upland crop and quantify yield potential and water use efficiency. This study reports on the results of cultivating the upland rice variety Apo under different water conditions in 2004-2005 at the IRRI farm in both the dry and wet seasons. The water treatments considered were: aerobic and flooded conditions, alternated flooded and aerobic conditions and aerobic after fallow. Yield and water productivity were compared between aerobic and flooded treatment in both seasons, with the objective of analysing the differences between water treatments. In the experiment the effect of different nitrogen (N) application is also considered. The results indicate that the aerobic rice yield was lower than rice production under flood treatment, confirming that observed over past years. Nevertheless, when the aerobic condition is alternated with the anaerobic condition, or a fallow period, the production under aerobic treatment provides good yields (respectively 4.2 and 4.4 ha-1). The fallow period was introduced to observe the response of rice grown under this management. Water productivity was higher in aerobic fields, especially after fallow (0.88 g kg-1). The nitrogen application induced an increase in yield and water productivity, partially compensating for the lack of water in aerobic fields.

The Role of Gender in Economic Activities with Special Reference to Women’s Participation and Empowerment in Rural Bangladesh

Bangladesh is known as a predominantly male-dominated society with traditional and religious beliefs that restrict women’s mobility and participation in economic and social activities. This article is based on national rural representative household-level data collected in 1987 and 2000 from 62 villages in Bangladesh jointly conducted by the International Rice Research Institute and Bangladesh Institute of Development Studies. First, this article depicts patterns of women’s work and analyzes the factors that influence the gender division of labor. Second, a women empowerment index is developed from the 2000 survey data on intra-household decision-making in different spheres, and its relationship with women’s work is then explored. The persistent gender division of labor in rural Bangladesh has been found to be associated with both economic and socio-cultural factors. Rural economic activities within the household were found to have a weak impact on women’s empowerment.

Study of the radioecological sensitivity of rice to radioactive contamination

This study focused on the radioecology of rice and explored how the French specificities of rice cultivation can be taken into account in risk assessment. The objective of the study was to characterize the radioecological sensitivity of rice with respect to an accidental release of radioactivity. We want to know if a uniform and specific deposit would involve the same contamination on representative paddy fields of Camargue. To model the transfer of the radionuclides in the rice caryopsis following an accidental atmospheric pollution, we used the classical modelling for the cereals which considers first the interception by the foliage (modelled by an interception ratio) then the translocation to the grain (modelled by a translocation factor). The values of the parameters (interception ratio, translocation factor and yield) were regionalized with the agronomical software ORIZA2000, developed by the IRRI (International Rice Research Institute). We partly calibrated ORIZA2000 for a French rice variety: Ariete, thanks to physiological data provided for International Cooperation Centre in Agronomical Research for Development (CIRAD). ORIZA2000 proposes a daily follow-up of the leaf area index which can be correlated with the interception ratio. Five simulations with various climates, irrigation managements, and technical uses have been inputted on ORIZA2000. The data inputted were extracted from the database AGROSYST from the French Institute for Agronomical Research (INRA) and from the CIRAD. We established two scenarios of contamination. The first one consisted in a single contamination of water. In this case, there is almost no difference between simulations. However, in each simulation (except for organic farming) it is relevant to notice that the fourth depletion of water leads to a significant variation of contamination. The second contamination scenario consisted in a double contamination of water and of air. In that case, technical practices are responsible of the highest source of variability of the grain contamination. The variability of the contamination is mainly due to the variability of the yield which has in the radioecological modelling a dilution effect. The rice produced by organic farming is more sensitive than the rice produced by conventional farming because of low yields.

Transpiration efficiency of rice ( Oryza sativa L.)

Transpiration efficiency (TE), defined as the total dry matter produced per unit of water transpired, is an important crop characteristic, especially when water resources are becoming scarcer in many regions. But, in contrast to other major food crops, very little is known about the TE of rice ( Oryza sativa L.) and its dynamics in relation to climatic conditions in typical rice environments. To close this knowledge gap, we characterized rice TE in several experiments with varying experimental and climatic conditions. All six experiments were pot studies conducted between 1994 and 2006 at the International Rice Research Institute, Los Baños, Philippines. Between experiments, arithmetic means of TE varied from 1.8 to 4.7 g dry matter per liter transpired, whereas linear regressions showed TE means between 2.2 and 4.0 g dry matter per liter transpired. Actual TE values were estimated to be about 10% higher because root biomass was not determined. The corresponding k-factor ranged from 1.4 to 5.1 Pa (arithmetic mean) and 1.3 to 5.0 Pa (linear regression slope), indicating a considerable effect of climatic conditions on CO 2 and water vapor diffusion processes at the leaf surface. The analysis of different experimental treatments could not show a significant effect of drought treatments or variety on TE, but significant effects of soil type and water by nutrient interactions were observed. We concluded that the TE of rice is in the lower range of other small grain cereals, possibly comparable to oat. The results of this analysis can serve as a reference for further work on the TE of rice but they need to be verified in studies covering a wider range of climatic conditions and in field experiments.

QTL analysis for yield related traits using populations derived from an indica-japonica hybrid in rice (Oryza sativaL.)

Introgression has been achieved from a wild species Oryza minuta (2n = 48, BBCC, Acc No.101141) into O. sativa subsp. indica IR71033-121-15. This introgression line was developed at International Rice Research Institute (IRRI) through embryo rescue as well as three backcrosses using IR31917-45-3-2 as a recurrent parent. These two IR lines resemble each other but differ in several important agronomic traits, which can be attributable to O. minuta introgressions. Out of 530 STS markers tested for introgression analysis, at least 14 introgressed chromosomal segments from O. minuta were detected throughout 12 chromosomes. Most of the introgressed segments were quite small in size, as they were detected by single markers and flanking markers were negative for introgressions. A population from the cross between japonica cultivar Junambyeo and introgressed indica line IR71033-121-15, consisting of 146 plants, was evaluated for ten agronomic traits. Genotyping of F2 lines and phenotyping from both F<sub>2</sub> and F<sub>3</sub> were considered for QTL analysis. A total of 11 single-locus QTLs (S-QTLs) were identified for ten traits, i.e. days to heading (DTH), panicle number (PN), spikelet fertility (SF), panicle length (PL), spikelet per panicle (SPP), grain length (GL), grain width (GW), grain length to width ratio (GLW) and grain thickness (GT) in both populations. The O. minuta derived alleles of QTLs, spp6, gl3, glw3, glw5 and t12 were detected in both populations indicating robust QTLs for these traits. QTLs from O. minuta introgression could be new sources of natural genetic variation for genetic improvement of rice.

Registration of TIL:455, TIL:514, and TIL:642, Three Rice Germplasm Lines Containing Introgressed Sheath Blight Resistance Alleles

Three rice (Oryza sativa L.) germplasm lines designated as TIL:455 (Reg. No. GP‐112, PI 642943), TIL:514 (Reg. No. GP‐113, PI 642944), and TIL:642 (Reg. No. GP‐114, PI 642945) contain a total of eight novel alleles with sheath blight (caused by Rhizoctonia solani Kühn) resistance backcrossed into an elite U.S. rice genetic background having good grain quality traits, early maturity, and glabrous leaves and hulls. These three germplasm lines were jointly released in 2007 by the USDA‐ARS, the Louisiana State University Agricultural Center, and the International Rice Research Institute. The novel sheath blight resistance alleles contained in these lines originated from ‘TeQing’ (PI 536047), a high‐yielding rice cultivar from China that is well known in the United States for its strong resistance to sheath blight disease. With the aim of identifying improved germplasm suitable for introducing novel sheath blight resistance alleles into tropical japonica breeding programs, a combination of phenotypic and molecular data was used to select three lines from among 262 random backcross introgression lines.

Student Opportunity: Short-Term Exposure to International Agriculture

Abstract Opportunities abound to apply crop science to solving many of the world’s food problems. International agricultural research centers (IARCs) provide a window through which students can see the need for improved agricultural productivity and briefly experience the rewards of working on difficult but important issues. In today’s world of highly technical graduate education, students find it difficult to obtain exposure to international agriculture due to the extreme constraints on their time. Programs for students that provide a short-term exposure to IARC strategies can have long-term benefits for the student as well as the international center. A short-term student exchange program between a US university and the International Rice Research Institute (IRRI) and a special course on rice (research to production) offered at IRRI provide students with unique insights for averting food riots in the future. Details of these educational efforts are described in this paper.

Sowing the Seeds of Expertise

AGRICULTURAL RESEARCHAn innovative training program at the International Rice Research Institute aims to hone the skills of established rice researchers and entice young scientists into the field.

Systems biology or the biology of systems: routes to reducing hunger

Systems biology or the biology of systems: routes to reducing hunger

Fall of a sudden a food crisis the world over!

I serve on the Board of Trustees of the International Rice Research Institute (IRRI) headquartered in the Philippines and at our last meeting in April this year (2008), the Board had to issue a statement to the press, for the first time since I joined. The IRRI host country, the Philippines, was experiencing a fast exhalation in the price of rice and an apparent shortage of the commodity. Mind you, for the people of Philippines and indeed most of Asia, rice is virtually life, rice is like water. So once the rice sector is affected, whole livelihoods are affected. But as we attended this particular meeting, food price riots were being reported in other parts of the world as well. One could ask: why all of a sudden are food prices rising the world over? A lot has been written about this whole situation by experts and observers who are much more informed and much more analytical than I, and more continues to be written.

Efficient authentic fine mapping of the rice blast resistance gene Pik-h in the Pik cluster, using new Pik-h-differentiating isolates

The Pik-h gene in rice confers resistance to several races of rice blast fungus (Magnaporthe oryzae), and has been classified as a member of the Pik cluster, one of the most resistance (R) gene-dense regions in the rice genome. However, the loss of a key mutant isolate has long made it difficult to differentiate Pik-h from other Pik group genes especially from Pik-m. We identified new natural isolates enabling the differentiation between Pik-h and Pik-m genes, and first confirmed the authenticity of the International Rice Research Institute (IRRI) “monogenic” line IRBLkh-K3, and then fine-mapped the Pik-h gene in the Pik cluster. Using 701 susceptible individuals among 3,060 siblings from a cross of IRBLkh-K3×CO39, the Pik-h region was delimited to 270 kb, the narrowest interval among the Pik group genes reported to date, in the cv. Nipponbare genome. Annotation of this genome region first revealed 6 NBS-LRR type R-gene analogs (RGAs), clustered within the central 120 kb, as possible counterparts of Pik-h and 6 other Pik group R genes. Interestingly, the Pik-h region and the cluster of RGAs were shown to be located 130 kb and 230 kb apart from Xa4 and Xa2 bacterial blight resistance genes, respectively, once classified as belonging to the Pik cluster. The closest recombination events were limited to the margins of the Pik-h region, and recombination was suppressed in the core interval with the RGA cluster. This fine-mapping, performed in a short time using an HEGS system, will facilitate utilization of the cluster’s genetic resources and help to elucidate the mechanism of evolution of R-genes. The presence of natural isolates also confirmed that evolution of Pik-h corresponds to pathogen evolution.

Special Feature

More Crop per Drop Ray Wu, Pioneer of Rice Research: In Memoriam Interview with the International Rice Research Institute (IRRI) — Perspectives on Rice Research

Genomics of Major Crops and Model Plant Species

Genomics of Major Crops and Model Plant Species