Climate-related challenges in rice production in Indonesia underscore the necessity for early-maturing rice varieties. Developing these varieties can enhance productivity by shortening cropping cycles, although the process is often time-consuming, costly, and requires testing across multiple locations. Thus, modeling approaches offer efficient means of simulating the performance of various early maturing rice varieties across many conditions. This study addresses the limited application of the ORYZA (v3) model in tropical settings by calibrating and validating it using field data from two early-maturing rice cultivars: Cakrabuana and Inpari 13. The research used nested split-plots with three replications, two irrigation treatments, continuous flooding (CF) and alternate wetting and drying (AWD), alongside three nitrogen dosage levels: 0 kg ha−1, 90 kg ha−1, and 180 kg ha−1 were implemented. Model calibration was based on observations of phenology and biomass, focusing on parameters such as developmental rates and biomass partitioning. Validation was conducted using independent field data, calibrated Cakrabuana and Inpari 13 crop parameters, and relevant climate and soil information. Cakrabuana met the metric standards, with RMSEn values of 0.11 to 0.17, NSE from 0.68 to 0.93, and MAPE between 0.08 and 0.13%. While, Inpari 13 met the standards for the weight of storage organs. Model tests revealed strong validity for Cakrabuana, while Inpari 13’s lower validity resulted from environmental sensitivity. These findings support the ORYZA (v3) calibrated model as a reliable support planting forecasts for Cakrabuana variety, while further calibration of Inpari 13 is needed.

Amphibious rice varieties are a promising solution to improve rice production resilience under climate change, especially with increasing uncertainty in rainfall patterns. This study uses two complementary methods: bibliometric analysis to explore global research trends on amphibious rice, and field research to optimize the Biobestari variety. The bibliometric analysis identifies key topics, collaborations, and publication patterns. The primary study tests Biobestari using two planting spacing methods, double row with alternating row width (Jajar Legowo is an Indonesian term), square planting and five levels of fertilizer application. The agronomic and economic performance of each combination was evaluated. Results show that amphibious rice, combined with efficient planting and eco-friendly fertilizers, improves productivity and achieves a profit ratio of 1.91. This suggests that amphibious rice is well suited for areas with irregular rainfall. Its adoption should be supported by government programs and farmer training. The study highlights the importance of integrating genetic improvement, good farming practices, economic feasibility, and policy support to build climate-resilient rice systems.

Providing precise fertilisation guidance is vital for improving productivity and reducing environmental risks, yet the adoption of precision fertiliser systems remains low. The study investigates farmers’ intentions to adopt an Internet-based rice fertiliser information system across three agroecosystems: irrigated (Yogyakarta), rainfed (North Sumatra), and tidal (Central Kalimantan), with 100 farmers from each region. Applying an extended version of the technology acceptance model and using PLS-SEM analysis, the findings showed that perceived usefulness, perceived ease of use, and social norms are key determinants influencing individuals’ intention to adopt. Institutional trust also promotes adoption, while experience has no significant effect. These findings highlight the importance of trust and targeted training to boost farmers’ digital engagement with precision fertilisation technologies.

Context or problem: Studies have shown that rice yields in Asia can be further increased, but achieving higher yields with high efficiencies of resource use will require the development and use of management practices customized to reduce the specific yield-limiting constraints of farmers. Objective or research question: We hypothesized that farmers' yields could be increased to an attainable target through participation of technical experts with farmer groups to identify and implement a group-specific integrated crop and nutrient management practice (ICNM), which combined an improved rice variety, optimum population of transplanted rice, and one site-specific nutrient management (SSNM) practice designed to achieve sufficient spikelets for the target yield. Methods: The ICNM of one farmer group was compared to the farmer's management practices (FMP) of an adjacent farmer group at three locations with irrigated rice, two locations with rainfed lowland rice, and two locations in rainfed tidal swamps in Indonesia. Each group had 14-55 farmers. Yield gaps were estimated from the difference between yield potential - simulated using actual weather conditions at each location - and the yield measured for each farmer. Results: The FMP yields averaged 63-69 % of yield potential for IR 64 at irrigated locations and 53-60 % of water-limited yield potential for IR 64 at rainfed locations. The ICNM increased yield compared to FMP by about 20 % at each location, largely through an increase in panicles and spikelets per panicle. With ICNM, > 40 % of farmers attained >= 80 % of yield potential at each irrigated location and > 40 % of farmers attained >= 70 % of the water-limited yield potential at three of the four rainfed locations. The ICNM increased costs for fertilizer, seed, nursery management, and transplanting by an average sum total of USD 53 ha(-1), but ICNM reduced use of insecticide and fungicide. With ICNM, pesticide use was reduced by an average of two applications resulting in an average savings of USD 23 ha(-1). The ICNM reduced yield-scaled costs, and the added net benefit with ICNM averaged 307 USD ha(-1). Conclusions: One SSNM practice - agreed upon by a farmer group and then used by farmers in the group - combined with an adapted rice variety and adequate plant population increased yield and income, while achieving for many of the farmers a targeted fraction of simulated yield potential.

Site-specific nutrient management (SSNM) for a rice ( Oryza sativa L.)-growing domain is typically developed by first using the nutrient omission plot technique (NOPT) to determine yield responses with added nitrogen (N), with added phosphorus (P), and with added potassium (K) and then conducting an evaluation experiment to verify an SSNM practice developed from the NOPT results. We hypothesized that an effective SSNM practice could be more rapidly developed through concurrent NOPT experiments and evaluation of a preliminary best-bet SSNM practice derived from experiences in other rice-growing domains. Our study domain was rainfed lowland rice in an Indonesian tidal swampland without past NOPT experiments and without a verified SSNM practice. Concurrent NOPT and evaluation experiments were conducted in the wet season (WS) and dry season across 20–25 farmers’ fields either directly or not directly influenced by tides. Rice yields and gross return above fertilizer cost for a preliminary SSNM practice were higher than for farmers’ fertilizer practice in both seasons and for two fertilizer practices based on soil tests in WS. The inherent ability of SSNM to adjust fertilizer rates for an attainable target yield and time fertilizer applications to match crop demand contributed to the superiority of SSNM. In NOPT experiments, relative yields without added N, without added P, and without added K respectively averaged 0.70, 0.89, and 0.88 across seasons and tidal locations. These relative yields enabled preliminary SSNM fertilizer rates to be further adjusted for the rice-growing domain. Rice growers in domains without a verified SSNM practice can benefit, before NOPT experiments are completed, by using generic SSNM guidelines for timing fertilizer applications and adjusting fertilizer rates for a target yield. After completion of NOPT experiments, the fertilizer rates can be further adjusted based on measured yield responses with added N, P, or K.

Implementing a cropping intensity program with rice cultivation four times a year (CI 400) can be achieved using early maturing varieties of rice. However, this development needs to pay attention to the adaptability of the varieties planted to ensure successful implementation. The adaptability approach is a combination of assessing stability and productivity potential. This concept has been developed and applied in several studies, including research on rice. However, this approach is considered less comprehensive because it is non-parametric and only focuses on one stability analysis. Therefore, a systematic integration of various stability analyses, including index methods, is needed to comprehensively assess adaptability, particularly for early-maturing rice in South Sulawesi. This region is characterized by a dynamic climate zone and is one of the top four highest rice producers in Indonesia. Meanwhile, this study aims to develop a comprehensive adaptability index and select the best early-maturing rice varieties, especially in South Sulawesi. The investigation was conducted in Bone, Soppeng, and Gowa over two seasons using a nested randomized complete block design, with organized replications in each environment (location-season). Additionally, there was a significant focus on the application of five early-maturing and two check rice varieties, with each factor repeated three times at each location, totaling 126 experimental units. The results showed that the adaptability index, by combining stability rank accumulation with yield min max standardization, was effective at assessing the yield potential and stability of early-maturing rice varieties in supporting CI 400. Inpari 13 had the best index value at 0.55, followed by Cakrabuana at 0.31; hence both were recommended as adaptive early-maturing rice varieties, especially in South Sulawesi.

The genotype evaluation process requires analysis of GxE interactions to ascertain the responsiveness of a genotype to various environments, including the development of early maturing rice. However, the concept of interaction is relatively specific to grain yield. In contrast, grain yield is highly polygenic, so assessment should be carried out with multivariate approaches. Therefore, multivariate assessment in evaluating GxE interactions should be developed, especially for early maturing rice genotypes. The study aimed to develop a comprehensive multivariate approach to improve the comprehensiveness and responsiveness of GxE interaction analysis. The study was conducted in Bone and Soppeng districts, South Sulawesi, Indonesia, in two seasons. The study used a randomized complete block design, where replications were nested across two seasons and locations. Two check varieties and five early maturing varieties were replicated three times in each environment. Based on this study, a new approach to GxE interaction analysis based on multiple regression index analysis, BLUP analysis, factor analysis, and path analysis was considered adequate, especially for evaluating early maturing rice. This approach combined days to harvest, biological yield, and grain yield in multiple linear regression with weighting based on the combination of all analyses. The effectiveness of the GxE interaction assessment was reflected by high coefficient of determination (R2) and gradient (b) values above 0.8 and 0.9, respectively. Inpari 13 (R2 = 0.9; b=1.05), Cakrabuana (R2 = 0.98; b=0.99), and Padjajaran (R2 = 0.95; b=1.07) also have good grain yield with days to harvesting consideration, namely 7.83 ton ha-1, 98.12 days; 7.37 ton ha-1, 95.52 days; and 7.29 ton ha-1, 97.23 days, respectively. Therefore, this index approach can be recommended in GxE interaction analysis to evaluate early maturing rice genotypes. Furthermore, Inpari 13, Cakrabuana, and Padjajaran are recommended as adaptive early maturing varieties.

Minimizing the problem of nitrous oxide emissions from paddy field that contributes to climate change is the key to increase fertilizer efficiency. Application of Nitrogen-Phosphorus-Potassium efficiently in combination with organic fertilizer is crucial to improve fertility of degraded soil without sacrificing the yield. A trial in 2022 dry season, as part of on-farm long term fertility experiment applied combination of chemical fertilizer and organic to explore changes in soil fertility, soil organic content and yield under double rice cropping system. The experiment was designed in Split Plot with 4 replications, has been conducting at the Sukamandi experimental station, ICRR. The main plot was 5 chemical fertilizers which were without fertilizer input as control, + PK, + NP, NK + and + NPK. The subplot was organic fertilizer: a dose of 2 ton manure ha −1 , straw compost with dose 5 ton ha −1 and without organic content as control. The results of cropping season 2022 showed that (1) combined application of organic and chemical fertilizer at plot +NK significantly improved the soil organic content and yield of rice, (2) Fertilization significantly affected the growth, yield of rice and the soil nutrient status, (3) Adequate supply of macronutrients N-P-K treatment resulted in higher grain yield and more efficient fertilizer use.

Primary risk to rice (Oryza sativa L.) production is salinity intrusion and water scarcity, leading to a shortage of irrigation water and yield reduction. We examine the impact's effects of alternate wetting and drying (AWD) vs. continuous flooding (CF) and microbe application on yields of three rice cultivars (Ciherang, Inpari 34 Salin Agritan, Inpari 35 Salin Agritan) grown under slight and moderate soil salinity in the dry season (DS) 2017 and 2018. Under slight soil salinity, AWD and CF had nonsignificant difference in grain yield. Under a moderate soil salinity level, there was a substantial decrease in grain yield (8.2%), number of productive tillers, seeds panicle-1, and weight of 1000 grains with the plants grown under AWD. Increased soil salinity levels resulted in lower yield reduction with microbial than without microbial treatments. 'Ciherang' showed superiority over 'Inpari 34' and 'Inpari 35' under AWD at slight soil salinity. However, the yield reduction in the moderate salinity level was more remarkable for 'Ciherang' (18.1%) than 'Inpari 34' and 'Inpari 35' (9.7%) as salinity-tolerant varieties. The AWD used almost one-third less irrigation supplement than CF. This greatly assists small farmers in reducing the additional cost of pumping water. On average, AWD improved total water productivity by 32.7% under slight and 20.4% under moderate soil salinity over CF. Here, we lay out the potential for small farmers in slight salinity lowlands areas of the northern coast of Java to apply AWD during the DS. Farmers could manage water efficiently to prevent further yield loss and improve farm profitably.

CONTEXT: Agricultural landscapes play a crucial role in global carbon sequestration and biodiversity conservation. The presence of trees outside forests has been recognized as a significant carbon pool, but it is crucial to acknowledge that these trees serve purposes beyond being a carbon sink. This study focuses on integrating border trees and home gardens as distinct land use classes in Indonesian Javanese agricultural land to assess their impact on carbon stock potential and biodiversity connections.OBJECTIVE: The objective is to classify and quantify the tree composition of these classes, estimate their carbon stock potential, analyze plant species diversity, and identify the ecological connections between home gardens and field borders.METHODS: To achieve this, high-resolution multispectral and Synthetic Aperture Radar images were used from four sampling areas covering 100 km2 each in Lamongan and Malang districts, East Java, Indonesia, for land cover/land use mapping. The land use function method was used to identify border trees and home gardens as separate land use classes. Carbon stock potential was estimated based on tree cover composition, while plant species diversity was analyzed through field surveys and farmer focus group discussions.RESULTS AND CONCLUSIONS: Crops with border trees cover approximately 28% to 48% of the cropland area in the study sites, while home gardens represent about 74% to 85% of the settlement area. This suggests a potential to double tree presence in these sites by adopting border trees and home gardens practices across the entire area. The median tree cover ratio was around 27% for border trees and 33% for home gardens. This stratification approach identified 31% to 50% more carbon stock compared to calculations using standard classes. Furthermore, home gardens and border trees show a positive correlation with species richness, indicating their role as keepers of biodiversity. Therefore, home gardens and border trees could serve as a sustainability indicator for agricultural land in the Javanese farm system.SIGNIFICANCE: This research contributes to sustainable agricultural practices and climate change mitigation. The stratification approach of identifying border trees and home gardens offers a cost-effective approach for the better computation of carbon stock and can lead to effective land use policies and conservation measures that promote ecological resilience. The study provides valuable insights for similar agricultural contexts worldwide, guiding efforts toward a more sustainable agricultural future.

Fusarium stem rot disease caused by Fusarium verticillioides has become one of the most serious issues confronting Indonesian farmers in recent years. An alternative option for suppressing this disease is to use indigenous microbes as an eco-friendly method to reduce synthetic fungicides. The objective of the research was to identify the molecular characteristics and effectiveness of an indigenous microbial consortium in controlling Fusarium stem rot disease. Identification of indigenous microbes is carried out based on molecular characters using universal primers, namely ITS-1/ITS-4 for fungi and 27F/1492R for bacteria. Nucleotide sequences were analyzed using Bioedit 7.2 version and MEGAX software. In vitro testing was carried out using the dual culture method for indigenous fungi and the disc diffusion method for indigenous bacteria. Meanwhile, in planta testing was conducted by evaluating a consortium of fungi and bacteria to control F. verticillioides in the field using a randomized block design with three replications, followed by a 5% DMRT test. The use of universal primer pairs ITS-1/ITS-4 and 27F/1492R succeeded in amplifying DNA bands of indigenous microbial isolates measuring ±600 bp and ±1465 bp, respectively. S6 and S9 bacterial isolates were identified as Bacillus cereus. JRP 7 and SEDF 6A isolates were identified as Trichoderma asperellum and JRP 10 isolate was identified as Penicillium raperi. All identification resulted in homology of >99%. The in vitro inhibitory reactions of isolates JRP 7, JRP 10, SEDF 6A, S6, and S9 against F. verticillioides were >60%. Disease severity of B6B9C10, B6B9C6, B6B9C7, B9C6C7, B9C7C10, and C6C7C10 treatments significantly proved their ability to control F. verticillioides in the field with a lower percentage of disease severity than positive controls, which are 23.33%, 18.89%, 23.33%., 21.85%, 14.07%, and 15.93%, respectively. The B9C7C10 consortium (S9 + JRP 7 + JRP 10 isolates) containing three species of indigenous microbes, i.e. B. cereus, T. asperellum, and P. raperi is the most effective at controlling F. verticillioides and may be developed for use as biopesticide products.

Cereals–soybean intercropping is not well studied, despite the importance of these crops in increasing agricultural profitability and ensuring nutritional and food security in Southeast Asia. We compared different intercropping practices (IPs) with monocropping practices (MPs) for their yield and economic performance by small-scale farms without mechanization. The treatments were IPs of rice–maize, rice–soybean, or maize–soybean compared with MPs of rice, maize, or soybean as sole crops, across three provinces in the rainfed areas of western Indonesia with a wet climate. Our results show that the yield advantages using the land equivalent ratio of the IPs were 44% for rice–maize, 54% for rice–soybean, and 63% for maize–soybean compared to MPs. Rice equivalent yield, maize equivalent yield, and the gross margin under IPs were significantly higher per cycle than under MPs; IPs provided a substantially lower cost of production and of paid workers. Compared to just rice, there were additional net return gains of USD 160 and USD 203 ha−1 per cycle under rice–maize and rice–soybean intercropping. Maize–soybean intercropping resulted in an additional net return gain of USD 153 ha−1 compared to just maize. These results suggest there is considerable potential for small farmers to increase their yields and profits by intercropping in rainfed areas with a wet climate.

Saline soil is a prospective land for expanding the soybean planting area in Indonesia, but no variety with the ability to adapt to this soil has currently been released. That objective of this esearch was to identify the salt-tolerant soybean germplasm accessions. The experiment consisted of two treatments and these were arranged in a randomized complete block design with three replications. The first factor was three soil salinity levels i.e. 1.44-1.72 dS/m (used as a check), 6.75±0.40 dS/m, and 10.48±0.30 dS/m. The second factor was 25 soybean accessions selected from previous salinity screening activity. Parameters observed were soil electrical conductivity (EC), plant height, yield and yield attributes, as well as K, Ca, and Na concentration in soil and plant. The results showed that salinity treatment increased the soil EC, Na concentrations in shoot and root, and reduced K, thereby causing a reduction in soybean growth, seed weight, and seed size. Meanwhile, MLGG 0169, MLGG 0640, MLGG 0767 (Lokon variety), MLGG 1109 (Dega 1 variety), and MLGG 1098 (Detam 2 variety) were identified as tolerant tosalinity level up to 10.48±0.30 dS/m. The tolerant genotypes were characterized by high ITC index, high seed yield, fewer reduction of seed yield, and mild leaf damage. The tolerances were likely determined by the ability to absorb more K and less Na, translocate more K from root to shoot, and higher K/Na ratio in shoot and root than Ca/Na ratio. It means the K/Na ratio is more important in determining salinity tolerance than Ca/Na ratio. Therefore, accessions can be used as gene source for salt-tolerant breeding, and Lokon, Dega 1, and Detam 2 varieties were recommended for saline soil.

Nutrient management and fertilizer application are paramount elements for increasing rice productivity. However, most of farmers are still applying fertilizer in an improper way and hence economic benefit of the yield remain low. The objective of this study was to examine various fertilizer recommendations and hence the best and efficient dose of fertilizer can be obtain to increase growth and yield of rice. This experiment was conducted in farmers irrigated lowland Sukabumi, West Java in dry season 2019. The material used was high yielding IR-64 rice variety subjected to six fertilizer recommendation, namely urea only (A), LKP (B), factory’s recommendation (C), PUTS, (D), KATAM (E) and farmer’s practice (F). This experiment was arranged in randomized block design (RBD) with four replications. The quantitative morphological and physiological traits and financial analysis were observed. The result showed that fertilizer significantly affected morphological, physiological parameters and grain yield of rice. PUTS and KATAM (9,7t/ha) treatments had higher grain yield compared to other treatments. Fertilizer by farmer’s practice tended lower in morphological, physiological and grain yield responses compared to other fertilizer recommendation. Similar pattern showed for yield components such as panicle number, grains number and % empty grain were also affected by fertilizer recommendation. Based on the financial analysis that treatment with LKP fertilizer recommendation had higher profit (75.61%) compared with farmer’s practice. That treatment can reduce fertilizer costs by 61.57%, can increase revenue by 14.04% and give a profit of Rp. 5,580,969,-.

Sustainability of rice (Oryza sativa L.) production in high-altitude tropical upland is challenged by various abiotic and biotic problems. The main problems include low temperatures and blast disease. Farmers in high-altitude tropical uplands of Indonesia are still growing traditional rice varieties due to the absence of improved adaptive varieties. Development of improved varieties which are adapted to the high-altitude upland environment is therefore needed to increase productivity. This study aimed to investigate the interaction of genotype and environment of upland rice varieties across ten high-altitude upland locations in Indonesia and to determine their adaptability in the target areas. In addition, screening on blast disease and grain quality analysis was performed to characterize the genotypes. Significant interaction effects between genotype and the environment were observed for all agronomic characters. Genotype adaptability was determined based on the regression coefficient of grain yield and the environmental index. Genotypes such as B14168E-MR-10 adapted well in locations with low environmental indexes. In contrast, genotypes such as B11592F-MR-23-2-2 adapted well in locations with high environmental indexes. Screening using ten rice blast races showed that upland rice genotypes had a broad spectrum of resistance. Most of the genotypes had intermediate amylose content in the grains. Recently, the lines B14168E-MR-10 and B11592F-MR-23-2-2 have been approved to be released as new, improved rice varieties for high-altitude upland in Indonesia, namely Luhur 1 and Luhur 2, respectively. Both varieties are expected to be adopted by farmers in high-altitude upland to increase rice productivity in this environment.

The purpose of this study was to evaluate (a) the performance of two modern rice varieties (non-tolerant and tolerant for saline soils) under different fertilizer management options, and (b) assess the yield gap and income increase through proper crop and nutrient management at different levels of soil salinity. Experiments were carried out in moderate and high levels of soil salinity in West Java, Indonesia. A split plot design with three replications was used. The main plots included two rice varieties, Inpari-30 Ciherang sub1 and Inpari-34 (tolerant variety for saline soils), and subplots included eight fertilizer management treatments. Farmer participatory field trials were also established across three levels of soil salinity with four different rice varieties, Sidenuk, Inpari 30, Inpari 34, and Inpari 35, and a fertilizer package consisting of organic and inorganic fertilizers. Under low and moderate soil salinities, Sidenuk and Inpari 30 with recommended practice had higher productivity and economic benefit compared to the saline tolerant rice varieties, Inpari 34 and Inpari 35. However, under high soil salinity, the yields of Inpari 34 and Inpari 35 with recommended practice were 93% higher than farmers’ practice, representing an exploitable yield gap of 1.3 t ha−1 and benefit above fertilizer cost of USD 301 ha−1. The combination of tolerant varieties and improved nutrient management use for rice production can therefore be used as a strategy for improving farmers’ income and livelihoods in coastal areas of Indonesia.

Abstract. Subekti NA, Sembiring H, Erythrina, Nugraha D, Priatmojo B, Nafisah. 2020. Yield of different rice cultivars at two levels of soil salinity under seawater intrusion in West Java, Indonesia. Biodiversitas 21: 14-20. A tendency to use saline water in rice production is rising in recent years, but the adaptation of variety under saline conditions is still questionable. The aim of the study was to evaluate the response of several rice cultivars on the growth and yield of rice under seawater intrusion in West Java. Two salt-tolerant cultivars (Inpari 34 and Inpari 35), two promising lines (PL-1 and PL-2) and two modern cultivars (Inpari 30 (Ciherang sub1) and Sidenuk) were evaluated in two soil salinity levels. In each farmer's field a Randomized Complete Block Design was applied with three replications per treatment. Results showed that Sidenuk and Inpari 30 produced same yield compared to tolerant varieties and promising lines during dry season under moderate soil salinity. There were not much different among the cultivars tested in terms of plant height and tiller number as well as the biomass and harvest index. However, under high soil salinity seed germination, plant height, number of tillers per plant, above-ground biomass, spikelet number, percent of sterile florets and productivity were significantly affected. Saline tolerant varieties Inpari 34 and Inpari 35 showed their superiority compared to non-tolerant varieties. Both varieties produced 40% higher yield than Inpari 30 (Ciherang sub 1) and Sidenuk.

Large areas of lowlands within tidal deltas have been reclaimed for crop production in Indonesia. However, major production constraints such as floods, seawater intrusion from tidal rivers, and adverse soils remain a significant problem, resulting in low rice yields (2-3 t ha(-1)) and production systems that are prone to risk. This review describes the recent progress in technology development, to address multiple abiotic stresses through the genetic improvement of rice. During the last 15 years, rice breeding programs and germplasm evaluation systems for coastal deltas have been revitalized. Local landraces, modern varieties and elite stress-tolerant genotypes were screened and physiological response to the stress and agronomic performance of promising genotypes were characterized. These efforts resulted in the release of the first series of flood- and salinity-tolerant varieties for lowlands in Indonesia. On-farm trials with these varieties demonstrated yield advantages of up to 125%, over popular varieties currently used by farmers in the marginal lowlands. Some of these varieties made an impact; Ciherang-Subl, a submergence-tolerant variety near-isogenic of Indonesia's popular variety (Ciherang), occupied over 430,000 ha of rice lowlands within four years of its release in 2012. There are large "exploitable yield gaps" between the attainable farm yield and mean farm yield, and appropriate crop and natural resource management guidelines for the new rice varieties are being developed. These achievements highlight opportunities for sustainable development in unfavorable rice environments of coastal deltas and are relevant to other areas in South and Southeast Asia.

There is conflicting informations regarding the advantages of planting of stock seed (SS) over Extension Seed (ES) classes. An experiment to study the effect of different seedclasses on grain yield and yield components of five rice varieties was carried out at two locations i.e. Sukamandi and Muara Field Station during the wet and dry season of 2009. The treatment consisted of five rice varieties, namely: Ciherang, Mekongga, IR64, Cigeulis and Situ Bagendit, and their respective seed classes: namely breeder seed, foundation seed, stock seed and extension seed. The experiment was arranged in a split plot design with three replications, where rice varieties were as main plots and seed classes as sub plots. Variables to be evaluated consisted of: quality of seed before sowing, plant growth, yield components and grain yield. Performance of the observed variable of each rice variety derived from four different seed-classes in each location and planting season were not significantly different. Differences of seed classes only affected the percentage of seed purity. There was no significant difference on the grain yield and the seed yield obtained from different seed classes of each variety. These results disprove the belief that the higher seed class the higher productivity, which was found to be a wrong perception. Seed certification is designed to maintain the genetic purity of variety and not to increase the productivity.