BRIDGING THE RICE YIELD GAP IN THE PHILIPPINES - Leocadio S. Sebastian,^* Pedro A. Alviola,^** Sergio R. Francisco^***

^* Deputy Director for Research and Development, Philippine Rice Research Institute, Maligaya, Munoz Nueva Ecija, Philippines.

^** Senior Science Research Specialist, Philippine Rice Research Institute, Maligaya, Munoz Nueva Ecija, Philippines.

^*** Chief Science Research Specialis, Philippine Rice Research Institute, Maligaya, Munoz Nueva Ecija, Philippines.

Rice remains the agricultural commodity with foremost political and economic significance in the Philippines. As a major staple, rice accounts for 35 percent of average calorie intake of the population and as much as 60-65 percent of the households in the lowest income quartile (David and Balisacan, 1995). Moreover, rice farming is the source of income and employment of 11.5 million farmers and family members. Rice contributes 13 percent to the Consumer Price Index (CPI), 16 percent to the Gross Value Added (GVA) of agriculture, and 3.5 percent to the Gross Domestic Product (GDP) (Gonzales, 1999). Due to its economic importance, rice has become the central focus of government agricultural policies.

Recent trend analyses indicate that the growth of the rice sector has become completely dependent on yield improvements (David and Balisacan, 1995 and Gonzales, 1998). Yield improvement can come in either of two ways: a) by shifting the yield frontier, i.e., breeding varieties that have significantly higher yield potential than our current varieties, e.g., New Plant Type; and b) by developing and promoting yield-enhancing technologies such as the use of high quality seeds and efficient fertilizers. The first option is not attainable in the immediate future considering that the yield potential of the majority of the newly-released varieties have not yet surpassed the yield of IR8, which was bred in the late 1960’s. The second alternative is more plausible because there are available yield-enhancing technologies.

2. STATUS OF RICE CULTIVATION

2.1 Area, Production and Yield Trends in Different Agro-ecologies

Trends in palay (rough rice) production, area harvested, and average yield per hectare are shown in Table 1. For the past three decades, palay production has increased from 5 Mmt (million metric tonnes) in 1970 to 11 Mmt in 1997 at an average annual rate of 3 percent. Consequently, area harvested also increased from 3.1 Mha (million hectares) in 1970 to 3.84 Mha in 1997, which grew at an average of 0.89 percent per year. In 1997, the national average yield per hectare was 2.93 mt/ha (metric tonne per hectare). The irrigated areas produce the highest average yield with 3.4 mt/ha, followed by the rainfed ecosystem at 2.1 mt/ha, and the upland areas at 1.5 mt/ha. However, production and area harvested were exceptionally low in 1998 due to the occurrence of the El Niño phenomenon.

Table 1. Philippine Palay Production, Area Harvested, and Yield/Hectare by Ecosystem.

ITEM	YEAR
	1970	1975	1980	1985	1990	1995	1996	1997	1998
	Production (m/mt)
All	5.32	6.38	7.65	8.81	9.32	10.54	11.28	11.27	8.55
Irrigated	2.95	3.45	4.51	5.82	6.60	7.60	8.23	8.48
Rainfed	2.01	2.60	2.88	2.83	2.59	2.76	2.82	2.59
Upland	0.36	0.34	0.26	0.15	0.13	0.19	0.23	0.21
	Area Harvested (m/ha)
All	3.11	3.63	3.47	3.31	3.32	3.76	3.95	3.84	3.17
Irrigated	1.43	1.49	1.61	1.84	2.01	2.33	2.48	2.50
Rainfed	1.29	1.74	1.60	1.33	1.21	1.30	1.30	1.21
Upland	0.38	0.39	0.27	0.14	0.10	0.12	0.16	0.14
	Yield per Hectare (mt/ha)
All	1.71	1.76	2.2	2.66	2.81	2.8	2.86	2.93	2.7
Irrigated	2.06	2.31	2.8	3.17	3.29	3.26	3.31	3.39
Rainfed	1.56	1.49	1.8	2.12	2.13	2.11	2.16	2.14
Upland	0.94	0.86	0.98	1.12	1.31	1.54	1.43	1.5

Source: PhilRice-BAS Rice Statistics Handbook, 1997.

2.2 Production Constraints and Issues in the Rice Industry

Despite technological breakthroughs in rice research, farm yield levels are still way below their maximum potential due to biological, technical, physical, socio-economic and policy constraints.

2.2.1 Biological-technical-physical constraints

Technology plateau: After the introduction of IR 8 in the late 1960’s, which triggered the green revolution in Asia, no genetic material introduction with the same magnitude of technological innovation has taken place. It is generally agreed among rice scientists that the technology plateau in rice took place in the late 1980’s.

Emergence of biotype: Rice production declined after the mid 1980’s due to the emergence of new biological problems. The development of new strains and biotypes of rice pests were compounded by the regular occurrences of natural calamities such as floods and drought. Reduced hectarage, poor maintenance of irrigation facilities, urbanization, and post harvest losses contributed to this decline.

Low technical efficiency: ‘PhilRice’ studies show that farmers have low technical efficiency relative to the best farmer performance. Also, first generation varieties are still used by nearly half of the farmers. Moreover, these varieties produce relatively low yield, poor grain quality, low milling recovery, and poor tolerance to biotic and abiotic stresses. Seeding rates are still high at 120 to 200 kg/ha.

Problem soils and declining soil fertility: An estimated 1.2 million ha which is about one half of the national rice hectarage, are classified as problem soils. Of the total hectarage of problem soils, 600,000 ha have adverse water and nutrient conditions; 100,000 ha are saline-prone; 10,000 ha are alkaline; 15,000 ha are peat soils; and 500,000 ha are acid sulphate soils.

2.2.2 Socio-economic constraints

Socio-Economic constraints are composed of farmers’ limited management capabilities to make correct decisions to increase their yield levels (hence profit) and the unfavorable policy environment which inhibits them from fully optimizing their decision making process.

Limited management skills of farmers: On average, there are more rice farmers in the Philippines who have limited skills in making rice farming an agribusiness venture. The relatively low fertilizer use and proper timing of application, accompanied by poor cultural management practices are major sources of inefficiency.

Deteriorating terms of trade: Although nominal protection of domestic rice production has been positive over the years, net effective protection has been declining due to higher protection on tradable inputs and overvaluation of exchange rates. This declining incentive implies bias against the rice sector in macro level resource allocation, and loss of benefits to farmers at the micro level.

Lack of appropriate and adequate infrastructure: Because of limited access to credit for processing and storage facilities, farmers are forced to sell their marketable surplus during harvest months when prices are low. Farmers cannot wait for a good price because they do not have a place to dry or store their rice. As a result, wholesalers dictate prices to retailers and consumers.

Another problem is the lack of effective irrigation systems, which is primarily constrained by: a) the substantial increase in costs for irrigation development; and b) management problems for large scale irrigation projects.

2.3 Yield Potential of Released Varieties

Based on multilocation advanced yield trials, the highest maximum yield recorded for irrigated lowland released varieties is 10.3 t/ha for PSB Rc34, a farmers’ selection, followed closely by PSB Rc66 with 10.2 t/ha. A promising rice line, which was still subject to approval for release as a rice variety in 1999, has a maximum yield of 12.0 t/ha. PSB Rc4 and PSB Rc20, on the other hand, have the lowest maximum yield of 6.1 t/ha.

Among the three recommended hybrids, PSB Rc72H has the highest maximum yield of 9.9 t/ha. These hybrids have a relatively lower maximum yield than the national record because they are recommended only for specific areas in the country where they have out yielded the inbred check by at least 12 percent.

For the less favorable environments, the highest maximum yield was attained by PSB Rc14 at 5.1 t/ha among the rainfed-recommended varieties, 5.5 t/ha by PSB Rc48 for the saline prone areas, 6.0 t/ha by PSB Rc3 for the upland ecosystem, and 4.7 t/ha both for PSB Rc44 and PSB Rc46, which are the only varieties recommended for cool elevated areas.

2.4 Evidence of Yield Gaps

Rice Yield Gap Analysis in the Philippines

The yield gap is the difference between potential yields and actual yields (Roetter, et al, 1998). The yield gap can be divided into two parts. Yield Gap I is the difference between experimental station yields and potential farm yields. It exists mainly because of environmental differences between experiment stations and the actual rice farms. The potential farm yield can be approximated by the yield obtained in on-farm experiments under non-limiting input condition. Yield Gap II is the difference between the potential farm yield and the actual farm yield. This gap reflects biological constraints, soil and water constraints and socio-economic constraints that compel farmers to use inputs at a level much below the technical optimum (Figure 1). A part of Yield Gap II could be reduced through research, development, and extension, e.g., developing resistant cultivars against various biotic (insects and diseases) and abiotic water-related stresses and through appropriate socio-economic policies.

Figure 1. Yield gap analysis framework.

Evidence from research stations suggests that substantial productivity gains are technically possible for rice. Yet farm level output continues to rise very slowly, if not stagnating in the past decades. At present, the average farmers’ yields only range from 50 to 70 percent of the on-farm experiment yield and only very few farmers have yields that are comparable to the demonstrated potential in on-farm experiments. The yield gaps that currently exist are consequences of biological constraints, soil and water constraints, and socio-economic constraints that compel farmers to use inputs at a level much below the technical optimum. Analysis shows that the average yields in the on-farm experiments from 1991 to 1995 were 5.7 t/ha during wet season and 7.5 t/ha during dry season while the average yields of the farmers are only 3.7 t/ha in the wet season and 3.9 t/ha during dry season. This corresponds to a yield gap of 2 t/ha during the wet season and 3.9 t/ha during the dry season (Table 2).

Table 2. Yield Gaps in Rice Production

	Wet Season	Dry Season
Simulated Potential On-farm Experiment Actual	7.8 5.7 3.7	9.0 7.5 3.9
Yield Gap I Yield Gap II	2.1 2.0	1.5 3.6

Simulated potential obtained by WOFOST 7.1 crop model On-farm experiment is average of LTCCE from 1991-95 Actual yield based on RBFH survey data 1996-97

With the current yield gap scenario faced by the country, the following activities are being vigorously pursued by the Philippine government in general and PhilRice in particular, to address the issue of rice yield gaps.

3.1 Making the Rice Research-Development-Extension (RDE) More Effective

The national rice RDE thrusts (Figure 2) emerged from an old structure that was implemented by PhilRice since it started its operations in 1987. PhilRice’s experience in its 13 years of R&D suggests the need to improve the synchronization of technologies, avoid missing technology components, reduce the lag phase from development to promotion of technologies, and develop location-specific technologies.

Figure 2. Conceptual paradigm of the integrated rice R&D structure and programmes.

The different RDE programmes currently implemented are interdisciplinary and ecosystem-based that integrate all the necessary components in each programme. These programmes are: a) Transplanted Irrigated Lowland Rice; b) Direct-Seeded Irrigated Lowland Rice; c) Hybrid Rice; d) Rice for Adverse Environments; e) Rice-Based Farming Systems; f) Rice and Rice-Based Products; g) Policy Research and Advocacy; and h) Technology Promotion and Development. Programme outputs are packages of technologies for specific ecosystems. In the Transplanted Irrigated Lowland Rice Programme, for example, researchers with diverse expertise work closely to develop a package of technologies for transplanted irrigated lowland ecosystems that would include the appropriate variety and the corresponding pest management options, nutrient management, and farm equipment. This programme involves a pool of researchers composed of breeders, geneticists, plant pathologists, entomologists, communication specialists, and policy researchers.

PhilRice’s collaboration with the national agencies through the National Rice R&D Network and international agencies strengthens the RDE and improves its effectiveness in addressing problems.

3.2 Improving the Long Term Yield Stability of Varieties through Breeding

From 1990 until 1998, the Philippine Seed Board has approved about 41 varieties for commercial release (as shown in Appendix 1). Of these, 21 varieties are suited for irrigated areas, 12 for rainfed areas, 3 for upland ecosystems and 4 for adverse environments. There are also three hybrid varieties that were developed to adapt to certain local conditions. These are PSB Rc26H (Magat), PSB Rc72H (Mestizo) and PSB Rc76H (Panay). These varieties were developed using mostly conventional methods. One variety was developed using anther culture. Most of the released varieties are of the IR 8 plant type that has a potential yield of 10 tons per hectare.

It has been observed that many of the released varieties often succumb to pests and diseases after a few years from their release. To remedy this problem, plant breeders are using different approaches, both conventional and biotechnological, to improve yield stability. Some approaches being to increase yield stability including alien gene transfer, and use of novel genes.

Conventional methods and biotechnology: As part of the national R&D programme for rice, the improvement of the performance of varieties is being pursued using both conventional and biotechnological approaches. Current goal of the programmes on irrigated rice (transplanted and direct seeded) is to increase average yield in the experiment stations all over the country to about 7.5 t/ha by the year 2001. This is being tackled by improving the resistance of new varieties against pests and diseases and tolerance to abiotic stresses such as drought. New materials are being used as source for these characters through hybridization and biotechnology.

Location-specific release of varieties: Another approach that is being pursued is the selective release of varieties for specific problem areas or regions. This is being pursued for areas like upland, saline-prone, and cool elevated areas. Regional releases undergo rigid testing including pre-release to farmers before final release. Pre-releases ensure acceptability of recommended varieties by farmers.

3.3 Improving Crop Protection and Pest Management

Pests and diseases are the significant factors that contribute to crop losses. An analysis done by Hossain, et al, showed that the production losses due to all reported source of loss were 945 kg/ha during the wet season and 1298 for the dry season. This represents 29 and 34 percent for wet season and dry season production, respectively. Except for calamities, such as typhoon and drought, the yield loss due to insects and diseases is the highest contributor (Table 3). The yield loss accounted for by insects and diseases was 26 percent in the wet season and 16 percent in the dry season. The major pests reported were golden snail, stemborer, tungro, BPH and rice bugs. Prevention of these losses would translate into increased productivity.

Table 3. Yield Losses Reported by Farmers from Household Survey, 1992-94.

Characteristics		Wet Season	Dry Season
Yield at harvest		3,270	3,822
Production losses		945	1,298
	Drought	198	759
	Typhoon/strong wind	358	253
	Floods	49	27
	Insect and diseases	250	206
	Inferior variety	25	11
	Lack of capital	48	42
	Others	17	0
Expected normal yield		4,215	5,120
Loss as percent of harvest		28.9	34.0

Source: Hossain, M., Gascon, F. and Revile M., 1995

PhilRice has established one of its branch stations in Mindanao, the PhilRice Midsayap branch, as the Rice Pest Management Centre in the country to coordinate all research activities on rice pest management.

3.4 Efficient Use of Fertilizer

Two aspects of nutrient management are being worked out in the Philippines, namely: improving balanced fertilization and determining the proper amount and timing of application. Despite the perennial presence of fertilizer as a component of government rice programmes, the average fertilizer use of rice farmers in the country is still relatively low when compared with the past and present fertilizer recommendations. Evidence shows that balanced fertilization strategy has a higher yield compared to farmer’s mode of application. At present, research is being undertaken to come up with site-specific fertilizer recommendations.

Based on the Balanced Fertilization Strategy (BFS) of the Bureau of Soils and Water Management, the recommended average kg N-use is lower by 46 percent during the wet season, but only by 20 percent for the dry season (Table 4). One possible constraint in using the optimal amount is the high cost of this input. Although farmers recognize the importance of fertilizer in getting higher yields, farmers are not applying it because its price becomes prohibitive. The share of fertilizer ranges from 13 to 15 percent of production cost.

Table 4. Farmers’ Fertilizer Use and BFS Recommendation.

	Average Farmer1		BFS Recommended2		% Difference
	WS	DS	WS	DS	WS	DS
N	54	100	100	125	46	20
P	11	33	30	30	63	-10
K	8	26	30	30	73	13
Yield	3.73	3.85	3.98	4.44	6.5	15.3

¹ 1996-97 RBFH Survey
² TechnoDemo protocol, 1998

Table 5. Method of Nitrogen Application in Nueva Ecija, Philippines, WS 1998.

Method	Yield (t/ha)	N Applied (kg/ha)	Factor Productivity (kg yield/kg N)
LCC	4.16	52	80.0
SPAD	4.17	81	51.5
FP	4.16	118	35.2

Source of Basic Data: ASD, PhilRice, 1997

Temporary fertilizer subsidies to farmers may be cost effective in stimulating farmers to adopt and appropriately use fertilizer together with new production technologies. Further, it may be effective in overcoming the fixed costs related to adoption of new technologies and inducing farmer experimentation and learning during the period of rapidly changing technological phase. However, such temporary subsidies should be phased out as adoption of the recommended rate becomes widespread in the target areas.

3.5 Use of Quality Seeds

The national survey of rice farmers in 30 rice-producing provinces conducted in 1997 revealed that although nearly 100 percent of our rice farmers are using modern rice varieties, only about 15 percent are using high quality seeds which include foundation, registered and certified seeds. Most of them still use either homegrown seeds or farmers’ seeds exchanged with neighbours. One basic reason for this low percentage of certified-seed usage is the lack of sufficient certified seeds, or if available, the high cost of quality seeds make it unaffordable to farmers.

Use of quality seeds has a yield advantage over that of farmers’ ordinary seeds. Analysis of actual on-farm data shows that the average yield of farmers using quality seeds is 12.6 percent higher than the mean yield of farmers using their home saved seeds across seasons. Thus, with the use of quality seeds alone, the yield gap can be lowered substantially. When aggregated for all irrigated areas, this translates into a production increment of 1.14 million tons of paddy (Table 6).

Table 6. Seed Utilization and Yield by Seed Class, Philippines, 1996-97.

Seed Class	Percent Using	Yield
Quality Seeds Farmer’s Seeds	15 85	4,010 3,560
Yield Advantage		12.6%
Aggregate Production Increment		1.14Mmt

Source of Basic Data: RBFH Survey 1996-97, SED

3.6 Expansion of Irrigated Areas

With a comparatively small area for rice production, one way to increase output is to increase the proportion of irrigated areas. With the favourable crop environment afforded by irrigated areas, not only cropping intensity is doubled, but also yield. Historical data analysis shows that the irrigated ecosystem has a yield advantage of more than one ton per hectare compared to rainfed areas yields. It is also important to improve maintenance of existing systems to prevent further deterioration (Table 7).

Table 7. Yields of Irrigated and Rainfed Rice, 1970-1997.

Year	Ecosystem		Difference
	Irrigated	Rainfed
1970-79	2.44	1.37	1.07
1980-89	3.14	1.80	1.34
1990-97	3.40	1.81	1.59
Average	2.99	1.66	1.33

Source of Basic Data: Philippine Rice Statistics, 1999

3.7 Intensifying Technology Promotion

The full productivity effects of yield-enhancing technologies can be best realized if the technically inefficient farmers can attain the performance of those operating in the frontier of current production technology. In order to bring the technology closer to farmers, PhilRice initiated the setting up of technology demonstration farms across the country. These farms showcase high yield technologies appropriate to the location. Results of the ‘Techno-Demo’ data analysis show that with better management and appropriate technology, yield increase of more than one ton per hectare can easily be realized (Table 8).

Table 8. Reduced Yield Gap II due to Technology Demonstration.

	Wet Season	Dry Season
On-farm Experiment Actual Techno-demo	5.7 3.7 4.9	7.5 3.9 5.5
Yield Gap Iia Yield Gap Iib Yield Gap II reduction	2.0 0.8 1.2	3.6 2.0 1.6
On-farm experiment is average of LTCCE from 1991-95
Actual yield from techno-demo data

Technology demonstration areas are established all over the country, technically supervised by PhilRice in cooperation with the local technicians and farmer cooperators. These demonstration areas showcase the latest rice technologies for adoption by farmers. Some of the technologies demonstrated are balanced fertilization, integrated pest management, and hybrid rice production. Field days are conducted to gather more farmers from other areas.

In support to these activities, PhilRice conducts massive training of rice farmers and extensionists to build their technical capability. Print and audio-visual materials have been developed to serve as useful reference materials to farmers and extensionists.

4. CONCLUSIONS AND RECOMMENDATIONS

There is a considerable yield gap between experiment station yields and farmer’s yields, which can be narrowed by increasing productivity. Although we have already developed technologies for increased productivity, some policy measures need to be initiated to maximize the potential of these technologies. Researchers should continue generating new technologies and fine tune existing ones to suit the needs of resource-poor and resource-rich farmers in the different environments. Policy and decision makers should ensure the timely delivery of the required inputs of production, e.g., quality seeds, fertilizer, irrigation and water to the farmers. Lastly, there is a need to strengthen further the existing extension systems in the country. Without an efficient extension system, technologies generated will not find their own way to the farmers.

REFERENCES

Barker R., Herdt, R. and Rose, B. 1995. The Rice Economy of Asia. WRF-IRRI

David, Cristina C. and Balisacan, Arsenio (1995). Philippine Rice Supply Demand: Prospects and Policy Implications. Philippine Institute of Development Studies, Makati City.

Gonzales, Leonardo A. (1999). The Global Rice Industry. Philippine Technical Bulletin. Volume 4. PhilRice Maligaya, Muñoz, Nueva Ecija.

Gonzales, Leonardo A. Philippine Rice Self-Sufficiency: The Elusive Dream. A paper presented at the 30^th Annual Scientific Conference of the Pest Management Council of the Philippines, PhilRice, Maligaya, Muñoz, Nueva Ecija, May 4-6, 1999.

Hossain, M., Gascon, F. and Revilla, I. 1995. Constraints to Growth in Rice in the Philippines. Jour. of Agric. Economics and Development. Vol XXXIII Nos. 1&2.

BAS-PhilRice, 1998.Philippine Rice Statistics.

Roetter, R., Aggarwal, P.K., Tan, P.S., Hoanh, C.T., Cabrera, J.M.C.A., and Nunez, B. 1998. Use of Crop Simulation Models and Alternative Yield Estimation Techniques for Optimizing Agricultural Land Use and Resource Management. In Exchange of Methodologies in Land Use Planning.

Rosegrant, M.W. and Pingali, P.L. 1991. Sustaining Rice Productivity Growth in Asia: A Policy Perspective. IRRI-SSD papers No. 91-01.

Serrano, S.R. 1993. Philippine Rice Policy: A Review. Paper presented at the International Seminar on Recent Trends and Future Prospects of Rice Farming in Asia. May 24-30, 1993. Seoul, Korea.

APPENDIX 1.

Rice Varieties Approved by Philippine Seed Board for Commercial Release from 1990-1998

Year	Variety	Popular Name	Breeding Institution	Ecosystem	Average Yield (mt/ha)	Maximum Yield in Test Sites (mt/ha)
1990	PSB Rc 1	Makiling	IRRI	Upland	2.40	3.90
1991	PSB Rc 2	Molawin	IRRI	Irrigated	4.90	7.10
1991	PSB Rc 4	Nahalin	IRRI	Irrigated	4.60	6.10
1992	PSB Rc 6	Carranglan	PhilRice	Irrigated	5.70	6.90
1992	PSB Rc 8	Talavera	PhilRice	Irrigated	5.40	7.10
1992	PSB Rc 10	Pagsanjan	IRRI	Irrigated	5.10	7.50
1992	PSB Rc 12	Caliraya	UPLB	Rainfed TP*	3.80	4.00
1992	PSB Rc 14	Rio Grande	UPLB	Rainfed TP*	3.80	5.10
1993	PSB Rc 16	Enanno	Traditional	Rainfed DS**	2.70	4.30
1994	PSB Rc 18	Ala	IRRI	Irrigated	5.10	6.50
1994	PSB Rc 20	Chico	IRRI	Irrigated	5.20	6.10
1994	PSB Rc 22	Liliw	UPLB	Irrigated	5.00	7.20
1994	PSB Rc 24	Cagayan	MRC	Rainfed	3.10	4.10
1994	PSB Rc 26H	Magat Hybrid	IRRI	Irrigated	5.60	7.60
1995	PSB Rc 28	Agno	IRRI	Irrigated	4.70	9.00
1995	PSB Rc 30	Agus	IRRI	Irrigated	4.70	8.00
1995	PSB Rc 32	Jaro	UPLB	Irrigated	4.70	8.80
1995	PSB Rc 34	Burdagol	Farmers’seln	Irrigated	4.80	10.30
1995	PSB Rc 36	Ma-ayon	Traditional	Rainfed	2.70	4.90
1995	PSB Rc 38	Rinara	Traditional	Rainfed	3.20	4.40
1995	PSB Rc 40	Chayong	Traditional	Rainfed	2.80	4.40
1995	PSB Rc 42	Baliwag	PhilRice	Rainfed	3.20	3.60
1995	PSB Rc 44	Gohang	IRRI	Cool Elevated	4.20	4.70
1995	PSB Rc 46	Sumadel	IRRI	Cool Elevated	4.20	4.70
1995	PSB Rc 48	Hagonoy	IRRI	Saline Prone	2.70	5.50
1995	PSB Rc 50	Bicol	IRRI	Saline Prone	2.97	4.30
1997	PSB Rc 3	Ginilingan Puti	Traditional	Upland	2.90	6.00
1997	PSB Rc 5	Arayat	IRRI	Upland	2.90	4.20
1997	PSB Rc 52	Gandara	IRRI	Irrigated	5.30	9.00
1997	PSB Rc 54	Abra	IRRI	Irrigated	5.00	6.60
1997	PSB Rc 56	Dapitan	PhilRice	Irrigated	5.30	7.50
1997	PSB Rc 58	Mayapa	UPLB	Irrigated	4.90	7.30
1997	PSB Rc 64	Kabacan	IRRI	Irrigated	5.00	8.90
1997	PSB Rc 66	Agusan	PhilRice	Irrigated	5.20	10.20
1997	PSB Rc 72H	Mestizo Hybrid	IRRI	Irrigated	5.40	9.90
1997	PSB Rc 60	Tugatog	IRRI	Rainfed DS**	3.60	4.50
1997	PSB Rc 62	Naguilian	PhilRice	Rainfed DS**	3.70	4.70
1997	PSB Rc 68	Sacobia	IRRI	Rainfed DS**	3.40	4.40
1997	PSB Rc 70	Bamban	IRRI	Rainfed DS**	3.20	4.50
1998	PSB Rc74	Aklan	UPLB	Irrigated	5.20	8.30
1998	PSB Rc76H	Panay Hybrid	AgroSeed	Irrigated	4.70	7.90

Source: Obien 1998
* Transplanted
** Direct Seeding