Philippine Rice Research Institute Research Articles

What Happened to PhilRice’s Microtiller? A Scaling Study

This study inquires on the outscaling of the microtiller, a machine developed by the Philippine Rice Research Institute (PhilRice) in the 1990s to address the tedious rice land cultivation in the Cordillera highlands of the Philippines. Stakeholders of the project were interviewed, particularly staff members of PhilRice and the Department of Agriculture; representatives of the Central Cordillera Agricultural Programme, PhilRice’s partner organization in developing and promoting the microtiller; and manufacturers and farmers in the area. It was found that while the machine offered a solution to the highly tedious land preparation issue, four key factors affected its scaling: absence of private sector engagement, lack of a business plan for scaling, lack of extension services, and the presence of a more versatile and cheaper competitor. This study provides empirical evidence of the usability of the set of scaling ingredients developed by PPPLab and the International Maize and Wheat Improvement Center to facilitate analysis of scaling of innovations. The findings may inform scaling opportunities and strategies for farm machines by agricultural research and development institutions across the globe.

Comparison of Microsatellite DNA Fingerprints of Original Seed Files and Conserved Rice Germplasm Collections

The understanding of the genetic identity and composition of germplasm collections conserved in a genebank is vital for the proper management of germplasm resources and utilization in various plant breeding programs. A study was conducted at the Genebank of the Philippine Rice Research Institute (PhilRice) to examine the genetic similarity of the original seed files (SF) and regenerated seeds conserved as an active collection (AC) using 18 microsatellite DNA markers and to explore their underlying intra-varietal heterogeneity. Here, 74 rice germplasm collections regenerated from 1992–2012 were randomly selected for the comparative DNA fingerprinting. The genetic similarity between the original SF and regenerated AC was examined through the Dice coefficient (DC) analysis, while the extent of intra-varietal genetic heterogeneity was determined via average-linkage cluster analysis based on binary genetic distance. Of the 74 collections studied, 68 showed paired clustering of SF and AC, indicating high genetic similarity. The DCs of these collections ranged from 0.79–1. On the other hand, SF and AC comparison of six germplasm collections yielded very low DCs ranging from 0.62–0.77, with their corresponding SF and AC pair dissociated in the dendrogram owing to their high intra-varietal genetic heterogeneity. The intra-varietal polymorphic alleles between SF and AC were observed in all markers analyzed – especially in RM562, RM547, and RM154 microsatellite markers –suggesting their potential use in assessing the levels of intra-varietal genetic heterogeneity in rice cultivars. This pilot study provides baseline information that may be used for potential integration of intra-varietal similarity or variability tests in the Genebank which are important aspects for effective germplasm conservation, management, and utilization. Also discussed in this paper are other insights regarding the intra-varietal genetic heterogeneity of the selected rice accessions.

EFFECTIVENESS OF TEXT MESSAGES TO TECHNOLOGY DISSEMINATION: A THEMATIC ANALYSIS

This study was conducted at Philippine Rice Research Institute located at Barangay Maligaya, Science City of Munoz, Nueva Ecija, and sought to determine the total number of text messages received by the PhilRice Text Center during the month of April in 2016. It also aimed to sort the text messages received according to categories/theme, the number of text messages per category/theme the frequency of the text messages from the regular texters, and the effectiveness of information on harvest and post-harvest based on the feedback obtained from the text messages. Results of the study show that the 4th week of April received the highest total number of text messages. On the most active regions in texting the Text Center, Region III, and Region XIII determined as the most active. On categories and themes, most of the text messages were on pest management, replies from senders, problems encountered, and plenty of seed availability and other seed-related concerns. . On the number of text per category/theme, the majority of the senders asked about seeds during the month of April. Senders asked if what seed varieties could be planted in the rainy season On the frequency of the texts of a regular texter, the data show that out of 2,691 texters all over the country, only 12 texters were determined as regular texters.

GENDER COMMUNICATION INTERPLAY APPROACH IN THE DEVELOPMENT OF GENDER FRIENDLY FARM MACHINERY IN SELECTED AGRICULTURAL AGENCIES IN THE PHILIPPINES

This study describes the gender sensitivity principles in a form of communication be applied in the development of gender-friendly farm machinery. The study includes an assessment of the engineer respondents towards their exposure to gender related topics. The study was conducted in selected agricultural agencies such as Philippine Center for Postharvest Development and Mechanization (PhilMech), Philippine Sino-Center for Agricultural Technology (PhilSCAT) at Science City of Munoz, Nueva Ecija, and Philippine Rice Research Institute (PhilRice) at Maligaya, Science City of Munoz, Nueva Ecija. Furthermore, to assess the opinion of the end-users to the agricultural machinery, the study was conducted to endorsed areas that adopted these technologies. The analysis of gathered data took place at Central Luzon State University, Science City of Munoz, Nueva Ecija. The researcher conducted this research from June to December 2018. To strengthen the claims of the study, interviews were conducted to achieve its objectives. The result shows that the engineers of PhilMech, PhilSCAT, and PhilRice have seldom exposure to gender-related topics, and some exhibits unfamiliarity with other terminologies used. The engineers’ sex, age, and civil status revealed to be significant in their exposure to gender-related topics. Generally, men farmers are more exposed to the identified agricultural machinery than women farmers who remain uninformed about controlling agricultural machinery. Today, women farmers are hindered towards information and equipment accessibility. Gender disparity in the agricultural sector remains a problem but farmers agreed that there must be machinery that can be easily manipulated by women which is push-button, lightweight, height considerate, easy to fix, riding type, and economically affordable.

Phenotypic Characteristics of Weedy Rice Variants of Central Mindanao

The presence of different weedy rice (WR) have already been reported in other areas of the Philippines. However, reports documenting its presence and phenotypic characteristics in Central Mindanao are not yet available. This study investigated the incidence, biology, and phenotypic characteristics of WR in Central Mindanao. Survey and collection were conducted in rice field areas of South Cotabato, North Cotabato, Sultan Kudarat, and Maguindanao from 2016–2017. Eight WR variants with distinct grain characteristics were identified and designated in 2016 DS (dry season); 24 variants in 2016 WS (wet season); 31 variants in 2017 DS; and 24 WR variants in 2017 WS. The most prevalent variants were WR-SuK3 (2016 WS), WR-SuK2 (2016 DS), WR-Min15 (2017DS), and WR-SuK3 (2017 WS). Germination test and characterization were conducted at the Philippine Rice Research Institute, Maligaya, Science City of Muñoz, Nueva Ecija. The collected WR variants had variable grain characteristics that affect grain quality and germinated earlier than cultivated rice, which makes WR more competitive. Under screenhouse conditions, all variants matured earlier and had better agronomic characteristics than cultivated rice (NSIC Rc 222). Identified agronomic characters of WR collected from Central Mindanao will be useful for advising control strategies to farmers.

Assessment of Genetic Diversity and Population Structure of Rice Donor Germplasm Accessions in the Philippines

Genetic diversity is necessary to safeguard potentially vital traits for adaptation to environmental stresses and a proximate defense against a resurgence of pests and diseases amid climate change. The hybridization core germplasm of the Philippine Rice Research Institute (PhilRice) comprises local and foreign landraces, varieties, and elite breeding lines, which are various sources for diversification and creation of superior rice varieties. The objective of the study is to investigate the level of genetic diversity and population structure across 472 parental germplasm using 17 polymorphic simple sequence repeat (SSR) markers as assistance for rice breeders in the selection of unique parents for hybridization. Germplasm accessions showed high genetic diversity (71%) and formed a structure delineating indica, temperate japonica, and tropical japonica – with 32.8% admixtures identified through the distance-based neighbor-joining (NJ) method, model-based Bayesian structure, and discriminant analysis of principal components (DAPC). Analysis of molecular variance (AMOVA) revealed that the majority of the variation (87.0%) was attributed to accession differences within a population, indicating regular seed movement limited to each subgroup rather than between population (8.7%), wherein the highest fixation index (FST) was observed between tropical and temperate japonica (FST = 0.13). The study established a PhilRice parental germplasm collection containing 306 genetically pure accessions retaining the majority of genetic diversity from the first collection, which offers a promising aid in generating favorable genetic gain through careful genotypic selection in rice breeding programs.

Growth and Yield Response of Upland Rice to Application of Plant Growth-Promoting Rhizobacteria

This study evaluated the effects of plant growth-promoting rhizobacteria (PGPR) isolates in enhancing upland rice growth and yield. Bacteria were isolated, screened for growth-promoting activities in vitro, biochemically identified, and tested under screenhouse conditions at the Philippine Rice Research Institute (PhilRice). Isolates exhibited growth-promoting activities, such as indole-3-acetic acid (IAA) production, tricalcium phosphate solubilization, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, siderophore production, and starch hydrolysis. The screenhouse experiment was conducted with upland rice (PSB Rc23) as the test crop, sterilized and natural soils, and recommended rate of inorganic fertilizers (RRIF) as other source variables. Results showed that significantly heavier shoot and root fresh weights are evident in plants grown in sterilized soil. Plants treated with full RRIF exhibited superior growth in terms of plant height, shoot and root weights, and grain yield. Among inoculated and fertilized plants, comparable growth promotion was obtained with Acidovorax delafieldii combined with half inorganic fertilizer rate, in terms of root fresh weight, shoot and root dry weights, plant height, grain yield, and nitrogen, phosphorus, and potassium (NPK) uptake. Overall findings show that PGPR (A. delafieldii) in combination with 50% RRIF is as effective as full RRIF in enhancing growth and yield of PSB Rc23 rice, implying that dependence on chemical fertilizer can be reduced utilizing this PGPR. However, further evaluation of these bacterial isolates in actual field conditions is necessary to uncover their efficiency as potential biofertilizer.

Role of biotechnology in rice breeding strategy of the Philippines

The breeding strategy implemented by the Philippine Rice Research Institute (PhilRice) is anchored in Agriculture 4.0 that aims to revolutionize the variety development system of the Philippines, thereby addressing the grand challenges the rice industry facing at present and in the future, considering the struggles of a sustainable agriculture in the face of global warming. It advocates a stronger and more cohesive variety development structure to keep up with the need of the times as well as climate change. Our breeders are challenged to produce a variety that will double the yield at the same time, climate and pest resistant with good eating quality and nutritious. Strategies implemented by PhilRice include the use of advanced methodologies in biotechnology and molecular biology as tools in developing rice varieties to hasten crop improvement, thereby addressing the grand challenges the rice industry facing at present and in the future.

Awareness and Perception of the Researchers of Philippine Rice Research Institute in Nueva Ecija in the Philippines on the Implementation of New Policy on Research and Publication

Research plays an important role in the generation of new knowledge and in the dissemination of valuable information. Academicians and scientists across the nations use research to prove or disprove both common knowledge and emerging concepts in various fields of discipline. For the information to be more scholarly and for it to gain wider readership, completed research works are submitted for peer-review and publication in journals. In the field of public administration, researches serve as bases for policy reforms and in the management of an organization’s public affairs. The academes, research institutions, and private companies also consider research output and publication as tools to assess the performance of their staff. To further simplify the process and encourage compliance, the Philippine Rice Research Institute (PhilRice) introduced in 2012 a policy reform on research publication through the issuance of administrative orders and memorandum orders. These issuances in PhilRice encouraged the researchers of this study to determine the level of awareness and perception of the PhilRice researchers on the new policies. Survey questionnaires are distributed to 37 staff assigned in the different research divisions of PhilRice. Analysis of data suggests that ninety-seven percent is aware of the policy on publication since it was disseminated through various media (emails, meetings, and colleagues). While all of the respondents support the policy, ninety-two percent suggests that for it to be fully-realized, certain provisions must be amended. The results of the study could be a potential source of information for administrators and decision-makers on how research can be used to enhance individual and institutional transparency and accountability. It could also serve as a basis for the further improvement of policies, and lastly, as a guide for future researchers who are interested to pursue similar study on a different setting.

Assessing the Transparency Practices in Public Bidding of Philippine Rice Research Institute in the Philippines

The objective of this paper is to describe the observance of the principle of transparency in government procurement as required by Republic Act 9184 also known as Government Procurement Act (GPRA) of 2003. The measurement of observance is in the domains of the observance of procedures on public bidding, participation of stake holders in the bidding proceedings and public access to bidding information. The study used the descriptive qualitative method of research. Interview was held and Focus Group Discussion (FGD) was resorted to undertake member checking and triangulation of responses. Purposive sampling method was used to select participants to the study. The researcher interviewed 6 participants from the Procurement and Property Management Division-BAC (Bids and Awards Committee) Secretariat Unit of Philippine Rice Research Institute who are in- charge of public bidding activities of the institution. The study found that there is observance of transparency in the procurement process conducted by the agency and the information on the bidding activities are highly accessible and downloadable through the Philippine Government Electronic Procurement System (PhilGEPS) and agency official website. The standard process in the implementation of the procurement activities embodied in the Implementing Rules and Regulations of RA 9184 is strictly observed. It is recommended that the same evaluation be done in some other government entities to determine observance of policy on procurement in the government sector. Keywords: Transparency, Government Procurement Public Bidding, RA9184, the Philippines, Public Administration DOI : 10.7176/PPAR/9-2-06

Development and Promotion of the Reversible Airflow Flatbed Dryer in the Philippines

A flatbed dryer with a reversible airflow was introduced in the Philippines through a collaborative project between Nong Lam University of Vietnam and the Philippine Rice Research Institute (PhilRice). In this design, airflow is reversed at some point during the drying period to achieve uniform drying without mixing the grain. An 8-ton capacity dryer was constructed at PhilRice Central Experiment Station in Nueva Ecija to evaluate its performance and adaptability under Philippine conditions. Appropriate and locally available materials were used in the construction of the pilot unit. Nine (9) additional dryers were then constructed at PhilRice stations (Nueva Ecija, Isabela, Negros, Agusan, Central Mindanao University, and Midsayap) that served as pilot units for technology promotion in their respective areas of coverage. Performance of the dryer was evaluated in terms of the following parameters: (1) drying; (2) quality of dried grains; and (3) economic analysis of using the dryer. The performance evaluation was conducted in three drying batches of newly harvested rice seeds. Paddy dried with the reversible airflow flatbed dryer at full load capacity has a uniform moisture content with one percent (1%) moisture gradient at different layers of the grain mass along the depth and across the drying bin. The drying rate was 1% moisture reduction per hour. The drying cost of using the reversible dryer is PhP0.74 per kg which is lower than the prevailing mechanical drying cost of PhP1.13 per kg. It has a payback period of 2.5 years and break-even point of 53.0 batches/year. To date, eight (8) privately-owned units have already been constructed and fully operational in the provinces of Nueva Ecija, Quirino, and Bukidnon, with PhilRice receiving inquiries from interested individuals here and abroad regarding the technology.

Prevalence, Agronomic Characteristics and Biology of Weedy Rice Biotypes of Nueva Ecija, Philippines

A survey of different weedy rice biotypes was conducted in rice field areasof Nueva Ecija from CY 2004-2006 to determine their prevalence, agronomiccharacteristics and biology. Surveys and quadrat samplings were conducted inrandom alongside of the roads to gather data on prevalence, height, numberof panicles/plant and density/m of weedy rice as well as the cultivated onesthey were associated. Studies on seed germination test, biology and agronomical characteristics of different weedy rice biotypes were also conducted at thelaboratory and screenhouse of Crop Protection Division, Philippine Rice ResearchInstitute. Five weedy rice biotypes designated as WR-NE 1, WR-NE 2, WR-NE3, WR-NE 4 and WR-NE 5 were found distributed almost everywhere in ricefields of Nueva Ecija. Among the biotypes, WR-NE 1 was the most common inmany rice fields. Prevalence of all biotypes around the province ranged from 1to 17%. In the field, all biotypes were found taller but had fewer panicles plantthan cultivated rice varieties. In the laboratory, all weedy rice biotypes emergedearlier than PSB Rc82 and IR64. Under screenhouse condition, all weedy ricebiotypes were taller, produced more leaves and culms plant than the cultivatedrice. WR-NE 5 was the tallest biotype while WR-NE 1 and WR-NE 2 had themost number of leaves and culms plant-1-1. All biotypes matured earlier but hadno seed shattering characteristics. The biotypes had comparable values in termsof flag leaf areas and LAI/plant with PSB Rc82. Shoot dry weight and number ofpanicles/plant of all biotypes was significantly higher than the control varieties.WR-NE 4 and WR-NE 5 had the longest panicles, longer and wider grains.Grains/panicle was highest in WR-NE 5 (102 grains/panicle). Grain lengthwidthratio (GLWR)of all biotypes, however,weresignificantly lowerthan thetwocontrolvarieties.WR-NE1 and WR-NE4 had the longest length of awnwhileWR-NE4 and WR-NE5 had the highest grain weight(both at 24 g/1000grains).The growthand developmentof the fiveweedyrice biotypes weremuchadvantageouscomparedto selected cultivarssuggesting their competitivenessandthreatin achieving the potential yield and quality of harvestedcultivatedrice. Keywords - Plant ecology, prevalence, agronomic characteristics, weed biology, biotype,Oryza sativa L., weedy rice, experimental design, Philippines

Standing Up for GMOs

On 8 August 2013, vandals destroyed a Philippine “Golden Rice” Field Trial. Officials and staff of the Philippine Department of Agriculture that conduct rice tests for the International Rice Research Institute (IRRI) and the Philippine Rice Research Institute (PhilRice) had gathered for a peaceful dialogue. They were taken by surprise when protesters invaded the compound, overwhelmed police and village security, and trampled the rice. Billed as an uprising of farmers, the destruction was actually carried out by protesters trucked in overnight in a dozen jeepneys.

Outcomes of Learning Online: The Case of Farmers and Extension Workers in the Philippines

The Philippines is now adopting information and communication technology (ICT) to promote agricultural sustainability and rural development. Among the development programs that apply ICT is the Open Academy for Philippine Agriculture (OPAPA) E-Learning Project by the Philippine Rice Research Institute (PhilRice), the agency mandated to spearhead research and development programs on rice. Following the most significant change (MSC) technique, this study was conducted to identify the most significant changes experienced by OPAPA E-Learning graduates composed of farmers, extension workers and agricultural science students. Results showed that respondents enrolled in the program to acquire knowledge of rice technologies, gain skills in operating a computer, update themselves about new farm technologies, and comply with academic and work requirements. Based on 20 MSC stories collected, the OPAPA E-Learning Project has led to the increase in knowledge of rice technologies and awareness of the program, improvement in school, farm and extension practices, and enhancement of computer skills. The Bennett Hierarchy of Program Outcomes revealed that the most significant change stories reported by the respondents correspond to higher levels of outcomes, indicating that the OPAPA E-learning Project has already made an impact in terms of improving its clientele’s knowledge and capability.

Community Participation and Intervention Framework (CPIF): Mechanism of Change in Rice Farming in Calatrava, Romblon, Philippines

This paper highlights the experiences of the Philippine Rice Research Institute in implementing the Give Me Five Rice Project (GM5) in Calatrava, Romblon. After the implementation of GM5 the Community Participation and Intervention Framework (CPIF) was developed. An analysis of the CPIF that describes the mechanisms of change in rice farming and how the level of peoples’ participation has influenced farmers’ attitude through technological adoption and adaptation in increasing rice productivity and income of the rice farmers. A cross-sectional survey design was carried out for this study. The interview-type study was conducted with fifty six (56) respondents: 49 were farmers and 7 were active stakeholders in the GM5 project in two (2) barangays (Pangulo and Balogo) in Calatrava, Romblon. Secondary data were gathered from the reports of the Rice Sufficiency Officers (RSO), and the final report of the GM5 project. Primary data were gathered through personal interviews by using a questionnaire and Focus Group Discussions (FGDs) with the key informants and other stakeholders. Descriptive analysis, Pearson correlation analysis and regression analysis were employed to analyze the data. Findings of this study showed that increase in yield and income had the highest relationship with level of technology adoption rate (r=0.772, p=0.000), followed by the level of peoples’ participation towards GM5 (r=0.702, p=0.000). These variables explained 71.40% of variation in increase in rice yield. As a result, the yield level of the farmers and income derived from the project show a significant increase (ρ = 0.000). This increase of yield and income is attributed to the high level of technological adoption and the high level of participation by farmers. This study also provided a number of implications and recommendations on how CPIF translates the increase of the level of community participation and yield and income of the rice farmers that will lead to people empowerment and food security in Calatrava, Romblon.

Making ICT Initiatives More Relevant: Creating Spaces for Farmers’ Participation in ICT Policies in the Philippines

There is a tendency for participation to be sidetracked in the highly infrastructure-centric discourse on information and communication technology for development (ICT4D). For some time, views anchored on technological determinism have dominated the discourse. Technology has been viewed as a “magic wand” that will serve as the answer to most development concerns. The discourse, however, has evolved as many ICT4D scholars have pushed for the social dimension of ICTs. It has been argued that if ICTs were to create significant impacts on the lives of the poor and the marginalised, ICT applications must stem from the identified needs of the community, and not just on the “global need” to modernize (Mansell, 2006). Heeks and Molla (2009) argue the interest on ICT4D studies has already shifted from readiness to impact. Readiness refers to the availability of the necessary ICT infrastructure to support ICT initiatives, while impacts focus on the value-added or the development contributions of ICTs (Heeks and Molla, 2009). All this is rooted from the growing discussion on the need to capture the development impact of multi-million dollar investments on ICT projects. We will argue in this paper that participation especially of the primary stakeholders in ICT projects is imperative if ICTs are to create significant impacts in their lives. Genuine participation, not tokenistic, will allow spaces for participation of the members of the community, which will result in more relevant ICT initiatives. It is hoped that by meticulously executing participatory mechanisms, pseudo-participation, which is unwittingly entrenched in many development projects worldwide, can be avoided. Pseudo-participatory mechanisms are rampant such that scholars have called for investigation of projects that purport to be participatory (Thomas, 2006). In this paper, we will proceed by first presenting the findings of the two research studies on ICT4D in Philippine agriculture commissioned by the Philippine Rice Research Institute (PhilRice). We will use these studies as take off points for the justification of the participatory mechanisms that we will forward in this paper. The studies, both national in scope, could lend methodological recommendations to assessing ICT for agriculture initiatives. To further strengthen our proposal, we will likewise present some ICT4D experiences from other countries that tried to employ the participatory approach. We attribute to a significant extent our appreciation of participatory communication to the works of Bessette (2004), Mefalopulos (2008) and Tufte (2009). We will also present some ways on how to make ICTs inclusive.

Adoption of leaf color chart for nitrogen use efficiency in rice: Impact assessment of a farmer-participatory experiment in West Bengal, India

Unbalanced and excessive use of N-fertilizers causes environmental pollution, lodging of plants and increased pest pressure, in addition to increased cost to farmers from excessively applied fertilizers and pesticides. N application at the right time and in right amount is critical for healthy plant and environment. Rice leaf color intensity is directly related to leaf chlorophyll content and leaf nitrogen status. The concept for the use of leaf color as an indicator to apply N in rice was crystallized during 1990s. The International Rice Research Institute and the Philippine Rice Research Institute developed a leaf color chart (LCC) that helps guide farmers for real-time nitrogen management in rice farming. The technology is inexpensive, and easily affordable by most resource poor rice farmers. In 2003 we initiated a farmer-participatory research to validate real-time N management in rice by the use of LCC in West Bengal state of India. After 3 years of validation research, a survey was conducted to assess the adoption and impact of LCC. The survey was conducted in both intervention and adjacent control villages and data were collected from 20% farm households selected randomly. In this paper, we report findings of the study on the determinants of adoption of LCC, and its effect on fertilizer and pesticides use.

Effect of Ground Water Irrigation on Paddy Rice Yield in Maligaya, Philippines

Air and water temperatures are important climatic variables influencing rice yields through the interaction of pests and nutrients. The Philippine Rice Research Institute (PhilRice) in Maligaya, central region of Luzon island, stated that the Philippines could attain rice sufficiency if farmers' average yield increases to at least 1 t/ha. It is generally said that decreasing the minimum air temperature in the rice canopy could make a yield increase possible in the Philippines. Instead, results showed that the timing of irrigation water application using a shallow tubewell pump in Maligaya could not decrease canopy air temperature. However, the temperature of the standing or flooding water in the field was reduced using pumped water or ground water irrigation compared with the conventional irrigation where water came from irrigation canals, and the lower temperature of the standing water resulted in an increase in rice yield from 7.27 to 8.58 t/ha for PSB Rc28 rice cultivar and from 3.08 to 4.02 t/ha for New Plant Type IR66106-5-3-2-3. Based on this result, this study recommends that rice growers irrigate using pumped water or ground water from 15: 00 to 17: 00 with a standing water level of 5 cm during the reproductive stage to have a lower water temperature at night for better efficiency of water and resistance to white heads.

Quantifying the Interactive Effect of Leaf Nitrogen and Leaf Area on Tillering of Rice

Relative tillering rate (RTR) increases linearly as leaf nitrogen concentration (NLV) increases in rice (Oryza sativa L.) plants. Leaf area index (LAI) has a negative effect on the emergence and survival of tillers. The objectives of this paper were to quantify the interactive effect of NLV and LAI on tillering in irrigated rice. Field experiments were conducted at Philippine Rice Research Institute (PRRI) and International Rice Research Institute (IRRI), Philippines during the dry seasons of 1995 and 1998. Two indica cultivars, IR72 and IR68284H, were subjected to various nitrogen (N) treatments. Number of tillers (including main stems), leaf area, and tissue N concentration were measured. The NLV explained a large part of variation in number of tillers m−2 among treatments. However, the residual, defined as the difference between observed and estimated number of tillers m−2, was negatively correlated with LAI (P < 0.01). When LAI was considered in addition to NLV, the model explained the variation in number of tillers m−2 much better, and the correlation between the residual and LAI declined and became insignificant (P > 0.05). The critical NLV and critical LAI for tillering to stop were interrelated; higher NLV was needed to prevent tillers from dying when LAI was high, and vice versa. Use of stem or shoot N concentration instead of NLV gave similar results. Results suggest that LAI, in addition to NLV, should be considered in predicting tillers in rice crop.

Rice Molecular Breeding at PhilRice

Biotechnology is one of the essential components of a food security strategy that the Philippine Rice Research Institute (PhilRice) is strongly pursuing. The institute's biotechnology research strategy is to derive as much benefits as possible from the biotechnological research activities of laboratories around the world, and concentrate on areas of special interest to the Philippines. The biotechnology research at PhilRice are then focused towards solving specific problems in the Philippines including the development of rice varieties adapted to Philippine conditions with pest and disease resistance and tolerance to abiotic stresses. The biotechnology research focus are currently on the following applications: a) Utilization of molecular marker technology to map agronomically important traits in rice such as yield components, resistance to rice tungro virus, green leafhopper, brown planthopper, and to develop/apply molecular marker aided selection techniques in rice improvement; b)Utilization of in vitro techniques in the development of lines with tolerance to adverse conditions (cold, salinity, drought) and improved grain quality; c) Molecular cloning of agronomically important genes like tungro resistance; d) Genetically engineer rice plants with resistance to bacterial leaf blight (BLB), blast, sheath blight, stemborer and tungro; and e) Transfer resistance genes (tungro, sheath blight, stemborer) from wild species to cultivated backgrounds. (Resume d'auteur)