Rice Production In Asia Research Articles

Nano fertilizer application under different establishment techniques for sustainable paddy (Oryza sativa L.) production

Rice production in Asia is a cornerstone of global food security. Implementing innovative crop establishment practices and utilizing nano fertilizers can enhance rice yields and mitigate environmental concerns, thereby contributing to a resilient and sustainable food system. Therefore, a field experiment was conducted over 2020 and 2021 that included various methods of application (seed treatment, root dipping, soil and foliar application) of nano fertilizers (nano nitrogen and nano zinc) under different rice establishment methods (conventional paddy and SRI). Statistical analysis was performed using Fisher’s analysis of variance and Duncan’s multiple range test (p ≤ 0.05). The findings showed that the application of 75% N and two foliar sprays of nano-nitrogen and nano-zinc at 25 to 30 and 45 to 50 days after transplanting under System of Rice Intensification method (Treatment T14) was statistically superior in improving growth and yield parameters, grain and straw yield, and in enhancing the quality of rice over other treatments. Studies revealed strong positive correlations between all the measures, with the exception of the proportion of chaffiness and unfilled grains. The results of the stepwise regression analysis revealed the percentage dependence of grain and straw yield on growth, yield, and quality factors.

The Threat of the Fall Armyworm to Asian Rice Production Is Amplified by the Brown Planthopper.

The recent invasion of the fall armyworm (FAW) into Asia not only has had a major impact on maize yield but is feared to also pose a risk to rice production. We hypothesized that the brown planthopper (BPH) may aggravate this risk based on a recently discovered mutualism between the planthopper and the rice striped stem borer. Here we show that BPH may indeed facilitate a shift of FAW to rice. FAW females were found to strongly prefer to oviposit on BPH-infested rice plants, which emitted significantly elevated levels of five volatile compounds. A synthetic mixture of these compounds had a potent stimulatory effect on ovipositing females. Although FAW caterpillars exhibited relatively poor growth on both uninfested and BPH-infested rice, a considerable portion completed their development on young plants. Moreover, FAW were found to readily pupate and survive in exceedingly moist soils typical for rice cultivation, further highlighting FAW's potential to switch to rice. We conclude that BPH, by changing the bouquet of volatiles emitted by rice plants, may greatly facilitate this switch. These findings, together with a current increase of nonflooded upland rice in Asia, warrant careful monitoring and specific control measures against FAW to safeguard Asian rice production.

Role of nuclear protein Akirin in the modulation of female reproduction in Nilaparvata lugens (Hemiptera: Delphacidae).

Introduction: Akirin as a highly conserved transcription factor, exerts a profound influence on the growth, development, immune response, and reproductive processes in animals. The brown planthopper (BPH), Nilaparvata lugens, a major pest in rice production in Asia, possesses high reproductive capacity, a critical factor contributing to reduced rice yields. The aims of this study were to demonstrate the regulatory role of Akirin in the reproduction of BPH. Methods: In this study, quantitative PCR (qPCR) was used to detect the mRNA expression of genes. RNA interference (RNAi) was used to downregulate the expression of Akirin gene, and RNA sequencing (RNA-seq) was used to screen for differentially expressed genes caused by Akirin downregulation. Hormone contents were measured with the enzyme linked immunosorbent assay (ELISA), and protein content was evaluated with the bicinchoninic acid (BCA) method. Results: Using BPH genome data, we screened for an Akirin gene (NlAkirin). An analysis of tissue-specific expressions showed that NlAkirin was expressed in all tissues tested in female BPH, but its expression level was highest in the ovary. After inhibiting the mRNA expression of NlAkirin in BPH females, the number of eggs laid, hatching rate, and number of ovarioles decreased. Transcriptome sequencing was performed, following a NlAkirin double-stranded RNA treatment. Compared with the genes of the control, which was injected with GFP double-stranded RNA, there were 438 upregulated genes and 1012 downregulated genes; the expression of vitellogenin (Vg) and vitellogenin receptor (VgR) genes as well as the mRNA expression of genes related to the target of rapamycin (TOR), juvenile hormone (JH), and insulin pathways involved in Vg synthesis was significantly downregulated. As a result of NlAkirin knockdown, the titers of JH III and Ecdysone (Ecd) were downregulated in unmated females but returned to normal levels in mated females. The ovarian protein contents in both unmated and mated females were downregulated. Discussion and conclusion: Our results suggest that NlAkirin affects female BPH reproduction by regulating the mRNA expression of genes related to the Vg, VgR, TOR, JH, and insulin signaling pathways, in addition to the titers of JH III and Ecd. The findings of this research provide novel insights into the regulatory role of Akirin in insect reproductive capacity.

Dynamic gene expression of southern rice black-streaked dwarf virus during its infection in rice plants and vector insects

In this century, a disease caused by southern rice black-streaked dwarf virus (SRBSDV) has resulted in significant loss in rice production in Asia. Aside from infecting rice plants, SRBSDV is transmitted by white-backed planthopper (WBPH) in a persistent propagative manner. Recent studies showed that SRBSDV can dynamically modulate the host cells throughout the infection progress. However, the expression dynamics of the SRBSDV genes during infection remain unclear. Here we established an absolute real-time quantitative PCR method to assess the dynamic of the SRBSDV genes expression in rice plants and planthoppers. Apart from displaying the expression levels of viral genes, we discovered that the expression level of viral genes in insects significantly surpasses that in plant cells. In addition, we identified two nonstructural proteins with unknown functions that exhibit the highest expression levels in plant and insect cells, respectively, which provide possible targets for restraining the disease outbreaks.

Opportunities for mitigating net system greenhouse gas emissions in Southeast Asian rice production: A systematic review

Southeast Asia (SEA) is a key producer and exporter of rice, accounting for around 28% of rice produced globally. To effectively mitigate greenhouse gas (GHG) emissions in SEA rice systems, field methane (CH4) and nitrous oxide (N2O) emissions have been intensively studied. However, an integrated assessment of system-level GHG emissions which includes other carbon (C) balance components, such as soil organic carbon (SOC) or energy use, that can positively or negatively influence the net capacity for climate change mitigation is lacking. We conducted a systematic review of published research in SEA rice systems to synthesize findings across four main components of net system emissions: (1) field GHG emissions, (2) energy inputs, (3) residue utilization beyond the field, and (4) SOC change. The objectives were to highlight effective mitigation opportunities and explore cross-component effects to identify tradeoffs and key knowledge gaps. Field GHG emissions were the largest contributor to net system emissions in agreement with existing scientific consensus, with results showing that practices such as floodwater drainage and residue removal are sound options for CH4 mitigation. On the other hand, increasing SOC potentially provides a large GHG mitigation opportunity, with long-term continuous rice cropping and practices such as residue incorporation and biochar application promoting SOC increase. A reduction in energy inputs was mainly achieved by optimizing agrochemical use, especially N fertilizers. For residue utilization beyond the field, GHG emission mitigation mainly came from preventing open field burning through residue removal. Removed residue can subsequently be used for producing energy that offsets GHG emissions associated with conventional fuel sources (e.g. fossil fuel-based electricity generation) or substituting material used in other production systems. Integrating all four components of net system emissions into one analysis underscores the following two main takeaways. First, the components of field GHG emissions and SOC change are the biggest opportunities for reducing net system emissions and need to be considered for effective climate change mitigation. Second, the reduction of C inputs through residue removal and increased soil aeration through multiple drainage will lower CH4 emissions but may also potentially decrease SOC stocks over time. Hence, we argue that future research needs to consider cross-component effects to optimize net system emissions, specifically the “stacking” of best management practices for mitigation related to field GHG emissions or SOC change in long-term experiments.

OsBLS6.2: A rice bacterial leaf streak resistance gene identified by GWAS and RNA-seq

Bacterial leaf streak (BLS), caused by Xanthomonas oryzae pv. oryzicola (Xoc), is a bacterial disease affecting rice production in Asia and Africa, whose severity is expected to increase with climate change. Identification of new quantitative-trait loci (QTL) or resistance genes for BLS resistance is essential for developing resistant rice. A genome-wide association study to identify QTL associated with BLS resistance was conducted using phenotypic and genotypic data from 429 rice accessions. Of 47 QTL identified, 45 were novel and two co-localized with previously reported QTL or genes conferring BLS resistance. qBLS6.2 on chromosome 6 explained the greatest phenotypic variation. Combined analysis of differential expression and annotations of predicted genes near qBLS6.2 based on haplotype and disease phenotype identified OsBLS6.2 (LOC_Os06g02960) as a candidate gene for qBLS6.2. OsBLS6.2 knockout plants showed higher resistance to Xoc than wild-type plants. Many other candidate genes for resistance to Xoc were identified.

Use of Food Attractant to Monitor and Forecast Population Dynamics of Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), a Long-Distance Migratory Pest

The rice leaf folder, Cnaphalocrocis medinalis, is a significant migratory pest that restricts rice production in Asia and Africa, and monitoring and early warning measures are the basis for its management. Based on its regional migratory path in China, the pest population dynamics were monitored from 2020 to 2021 using food attractants. In this study, we also used internal reproductive system dissection to determine the adult age and reproductive developmental state. The monitoring results indicated that the trapping dynamics of C. medinalis males using food attractants and sex pheromones were approximately similar. Both trapping methods yielded C. medinalis males of different ages, with an identical age structure for both trap types. Dissection analysis of the reproductive system of females trapped using the food attractants indicated that in 2020, the population of C. medinalis in Liling, Hunan Province, was indigenous, while populations in other monitoring sites mainly comprised migrants from other areas. The ovarian development level of females trapped using food attractants showed a positive correlation with the age of males, and there was also a significant positive correlation between the index of ovarian development of females and the mating time. Furthermore, a dynamic prediction method for fecundity in field populations was established based on the quantity of eggs held by the females. This study provides a new method for the monitoring and early warning of the existence of C. medinalis populations.

Contrasting area and yield responses to extreme climate contributes to climate-resilient rice production in Asia

Climate impacts on crop production components other than yield, i.e., area and cropping intensity, remain under-studied. Here, we clarify climate-crop area relationships by analyzing subnational census area and yield data for six multi-rice cropping countries in South and Southeast Asia. Extreme climate has a greater influence on the departure of area and yield from long-term trends than the average seasonal climate; precipitation and temperature in the sowing period of the wet/rainfed season have a greater influence on variability of the total annual area than in the growing period. In 57% of the country-scenario cases showing significant changes in area and/or yield, the directions of the area and yield responses to climate are not synchronized, deriving non-significant production changes under projected climates. Climate-area relationships not only limit production shocks, but also clarify uncertainties associated with climate mitigation of agricultural land, where area markedly affects the scale of mitigation.

Erratum]Occurrence Patterns of Three Planthopper Species in Asian Rice Production Regions

Erratum]Occurrence Patterns of Three Planthopper Species in Asian Rice Production Regions

Fenclorim rice safening and weed control with fall‐applied acetochlor and pyroxasulfone

AbstractApplications of very long‐chained fatty acid elongase (VLCFA)‐inhibiting herbicides are currently not labeled within U.S. rice (Oryza sativa L.) production but have been used in Asian rice production to suppress weedy rice and control other annual grasses and small‐seeded broadleaves. Therefore, separate experiments were initiated in the fall of 2019 and 2020 to evaluate rice tolerance and weedy rice (O. sativa L.) control with acetochlor and pyroxasulfone in the following spring. A three‐factor experiment within a randomized complete block design was implemented with the factors being (1) herbicide choice (acetochlor or pyroxasulfone), (2) a low or high herbicide rate (2100 and 4200 g ai ha−1, and at 237 and 475 g ai ha−1 acetochlor and pyroxasulfone, respectively), and (3) without or with a fenclorim seed treatment (2.5 g ai kg−1 of seed). Throughout the experiments, rice exhibited <10% injury with acetochlor. The fenclorim seed treatment reduced injury (averaged over herbicide choice and rate) from 28% to 21% 28 days after emergence of rice for both trial types. Fenclorim also improved rough‐rice yield (averaged over herbicide choice and rate) by 12 and 18 percentage points for the two different studies. However, regardless of fenclorim, rice did not demonstrate <20% injury with pyroxasulfone. The fenclorim seed treatment or any interaction containing fenclorim did not influence weedy rice control, and weedy rice control with acetochlor ranged from 0% to 48%. Findings from this experiment demonstrate the effects of a fenclorim seed treatment for fall‐applied acetochlor and pyroxasulfone and the efficacy of acetochlor and pyroxasulfone for controlling weedy rice.

Occurrence Patterns of Three Planthopper Species in Asian Rice Production Regions

Occurrence Patterns of Three Planthopper Species in Asian Rice Production Regions

Evaluation of rice tolerance and weed control with acetochlor and fenclorim

AbstractMany problematic weeds have evolved resistance to herbicides in mid-southern U.S. rice fields. With the lack of new effective herbicides, rice producers seek alternatives that are currently not labeled for rice production. Inhibitors of very-long chain fatty acid elongase (VLCFA) are currently not labeled for use with U.S. rice crops but are labeled for use in other U.S. row cropping systems and rice production in Asia. Previous research has demonstrated the utility of VLCFA inhibitors for weed control in rice; however, these herbicides induce variable amounts of injury to the crop when applied early in the growing season. Experiments were initiated in 2020 and 2021 at the Rice Research and Extension Center near Stuttgart, AR, to evaluate rice tolerance and weed control with acetochlor and seed treatment with a herbicide safener, fenclorim. Three rates of a microencapsulated formulation of acetochlor (630, 1,260, and 1,890 g ai ha−1), four application timings (preemergence, PRE; delayed-preemergence, DPRE; spiking; and 1-leaf), and without or with the fenclorim seed treatment (2.5 g kg−1 of seed) were used to evaluate rice tolerance, weedy rice control, and barnyardgrass control. Acetochlor applied DPRE at 1,260 g ai ha−1 provided better weedy rice and barnyardgrass control than applications at the 1-leaf stage at the same rate. Acetochlor rates of 1,260 and 1,890 g ai ha−1 reduced barnyardgrass and weedy rice densities by more greater than the 630 g ai ha−1 rate. The fenclorim seed treatment did not influence weedy rice or barnyardgrass control but did reduce injury for DPRE acetochlor applications. Based on these results, acetochlor can be safely applied to rice DPRE (≤19% injury) at 1,260 g ai ha−1 when the seed is treated with fenclorim, leading to ≥88% barnyardgrass and ≥45% weedy rice control 28 d after treatment.

Coupling life cycle assessment and global sensitivity analysis to evaluate the uncertainty and key processes associated with carbon footprint of rice production in Eastern China.

An accurate and objective evaluation of the carbon footprint of rice production is crucial for mitigating greenhouse gas (GHG) emissions from global food production. Sensitivity and uncertainty analysis of the carbon footprint evaluation model can help improve the efficiency and credibility of the evaluation. In this study, we combined a farm-scaled model consisting of widely used carbon footprint evaluation methods with a typical East Asian rice production system comprising two fertilization strategies. Furthermore, we used Morris and Sobol' global sensitivity analysis methods to evaluate the sensitivity and uncertainty of the carbon footprint model. Results showed that the carbon footprint evaluation model exhibits a certain nonlinearity, and it is the most sensitive to model parameters related to CH4 emission estimation, including EFc (baseline emission factor for continuously flooded fields without organic amendments), SFw (scaling factor to account for the differences in water regime during the cultivation period), and t (cultivation period of rice), but is not sensitive to activity data and its emission factors. The main sensitivity parameters of the model obtained using the two global sensitivity methods were essentially identical. Uncertainty analysis showed that the carbon footprint of organic rice production was 1271.7 ± 388.5kg CO2eq t-1 year-1 (95% confidence interval was 663.9-2175.8 kg CO2eq t-1 year-1), which was significantly higher than that of conventional rice production (926.0 ± 213.6kg CO2eq t-1 year-1, 95% confidence interval 582.5-1429.7kg CO2eq t-1 year-1) (p<0.0001). The carbon footprint for organic rice had a wider range and greater uncertainty, mainly due to the greater impact of CH4 emissions (79.8% for organic rice versus 53.8% for conventional rice). EFc , t, Y, and SFw contributed the most to the uncertainty of carbon footprint of the two rice production modes, wherein their correlation coefficients were between 0.34 and 0.55 (p<0.01). The analytical framework presented in this study provides insights into future on-farm advice related to GHG mitigation of rice production.

Effect of the Asian monsoon on the northward migration of the brown planthopper to northern South China

AbstractAs wind‐borne migration of insects is strongly influenced by atmospheric circulation and weather systems, the relationships between insect population abundance and meteorological conditions are substantial. The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the major wind‐borne insects hampering rice production in Asia, and its migration is significantly influenced by the Asian monsoon, a main component of the Asian climate system. However, the degree and mechanisms of the effects of monsoon on BPH migration have been little studied. In this paper, the effect of the Asian monsoon on the northward migration of BPH from the Indochina Peninsula to northern South China (NSC) was investigated based on the BPH light‐trap data and meteorological data for 39 years. The results show that the level of BPH migration in May could indicate the degree of annual pest outbreaks in NSC and that the southeast monsoon was more critical in this northward migration than the previously recognized southwest monsoon. The significance of the southeast monsoon stemmed from the strong effect of South China Sea subtropical high on BPH migration under a unique weather system distribution, the Polar low–Continental low–West Pacific subtropical high pattern. Furthermore, based on the key areas of migration obtained from the composite analysis, the multivariable linear regression prediction model could effectively predict the occurrence of BPH in NSC. These results indicate the importance of interactions between monsoons during BPH northward migration, which reflects the complex relationship between BPH migration and atmospheric motion.

Evaluating crop models to assess rice yield potential in Argentina

Due to the high concentration of the rice production in Asia, the study and comprehension of rice producing chains outside this continent are key to guarantee the global food security. The objectives of this study were to validate the SimulArroz and ORYZA v3 crop simulation models for rice production in Argentina, estimate the yield potential (Yp) for different sowing dates with both models, and estimate how much Argentina can increase rice production in the current agricultural area by reducing the yield gap. Two contrasting rice models (ORYZA v3 and SimulArroz) were used. Besides both are mechanistic models, Simularroz model requires fewer coefficients than ORYZA v3,. which may increase the systematic error. The coefficient of determination between simulated and measured values was at least 0.74 for grain yield and 0.97 for phenology. RMSEn values for phenology ranged from 5.7% to 9.4%. Both models simulated grain yield accurately at high yield levels (>13 ​Mg ​ha−1) with an RMSE <0.5 ​Mg ha-1. The average irrigated rice Yp for subtropical Argentina estimated by the SimulArroz model ranged from 3.8 to 15.6 ​Mg ​ha−1, and from 7.6 to 14.3 ​Mg ​ha−1 in the ORYZA v3. The differences in the Yp between the models were due to different approaches in the calculation of thermal sum and radiation use efficiency. The increase in the rice production in Argentina if the fields close the exploitable gap (80% of the Yp) would be 42% of the current total rice production or 916,091 ​Mg annually.

IDENTIFICATION OF RESISTANCE SOURCES IN DIVERSE RICE GERMPLASM AGAINST SHEATH BLIGHT DISEASE CAUSED BY Rhizoctonia solani

Sheath blight of rice caused by Rhizoctonia solani, is the most serious disease severely damaging the rice production in Asia including Pakistan. Durable solution is a dire need to manage this disease for which the study was planned to identify the resistance sources in advanced local and exotic rice germplasm. Development of resistant varieties is the most reliable, economical and efficient strategy to manage this disease. The objective of the present study was to identify the genotypes harboring resistance against sheath blight disease in rice. To cope this issue, rice germplasm (85 advance rice lines/mutants/varieties) originated from IRRI and Pakistan were inoculated with Rhizoctonia solani through toothpick inoculation method under field conditions during 2020 and 2021. The results revealed that none of the genotype reflected immune response against sheath blight disease while two rice varieties, Noor Basmati and IRRI-29 with disease severity (15.21-15.77% and 18.39-19.97% respectively) were found resistant in both years. Eight varieties/lines Basmati 515, Chenab basmati, Punjab basmati, NM-7, NM-11, NM-15, NM-16 and NM-17 categories as moderately resistant with the disease severity ranging from 21 to 30% in both years. 26 varieties/lines were found moderately susceptible with the disease infection of 31.33 to 44.94% while 49 were susceptible with 45.72 to 65.26% in 2020-2021. The resistant and moderately resistant genotypes could be used in breeding program to develop sheath blight disease resistant cultivars in Punjab, Pakistan.

Comparative Genomic Analysis of Two Xanthomonas oryzae pv. oryzae Strains Isolated From Low Land and High Mountain Paddies in Guangxi, China.

Xanthomonas oryzae pv. textitoryzae (Xoo) is a causal agent of rice bacterial leaf blight (BLB), the major rice disease, which is seriously constraining rice production in Asia. The interaction between Xoo and rice is in a dynamic process, essentially the co-evolution. Tracking the occurrence of plant diseases and identifying the epidemic pathogens in time are critical to assessing the epidemic disease status and understanding the pathogen evolution. In 2020, the occurrences of rice BLB were spotted in many places of Guangxi, the major rice growing region in China. Two of the 2020-epidemic Xoo strains, namely, GXO20-01 and GXO20-06, were isolated from low land and high mountain paddies in Guangxi, respectively, and were demonstrated to be race R8 of Chinese Xoo strains, but with significantly different virulence on certain susceptible varieties of rice. The HiFi PacBio sequencing revealed that GXO20-01 and GXO20-06 share the highly syntenic genome structures and the major genome contents, but only differ in <10 genes, including one gene encoding for transcription activator-like effector (TALE). A phylogenomic analysis grouped GXO20-01 and GXO20-06 into the PX-A lineage, stood close to PXO563 and PXO71 strains, but stood away from the other Chinese Xoo strains; for example, the JL25 and YC11. A comparative genomic analysis revealed that the major pathogenicity/virulence genes are conserved in two, newly isolated Xoo strains and the other Xoo strains in PX-A lineage, including the majority genes for the TALomes. The genomic differences between the Xoo strains were pinpointed to a few tal genes, which were variable in both their numbers and sequences, even between GXO20-01 and GXO20-06, the two 2020-epidemic Xoo strains. The study further revealed the instability and variability of tal genes in Xoo and highlighted the utility of HiFi long-read sequencing in TALE analysis and pathogen tracking.

A Scalable Machine Learning Pipeline for Paddy Rice Classification Using Multi-Temporal Sentinel Data

The demand for rice production in Asia is expected to increase by 70% in the next 30 years, which makes evident the need for a balanced productivity and effective food security management at a national and continental level. Consequently, the timely and accurate mapping of paddy rice extent and its productivity assessment is of utmost significance. In turn, this requires continuous area monitoring and large scale mapping, at the parcel level, through the processing of big satellite data of high spatial resolution. This work designs and implements a paddy rice mapping pipeline in South Korea that is based on a time-series of Sentinel-1 and Sentinel-2 data for the year of 2018. There are two challenges that we address; the first one is the ability of our model to manage big satellite data and scale for a nationwide application. The second one is the algorithm’s capacity to cope with scarce labeled data to train supervised machine learning algorithms. Specifically, we implement an approach that combines unsupervised and supervised learning. First, we generate pseudo-labels for rice classification from a single site (Seosan-Dangjin) by using a dynamic k-means clustering approach. The pseudo-labels are then used to train a Random Forest (RF) classifier that is fine-tuned to generalize in two other sites (Haenam and Cheorwon). The optimized model was then tested against 40 labeled plots, evenly distributed across the country. The paddy rice mapping pipeline is scalable as it has been deployed in a High Performance Data Analytics (HPDA) environment using distributed implementations for both k-means and RF classifiers. When tested across the country, our model provided an overall accuracy of 96.69% and a kappa coefficient 0.87. Even more, the accurate paddy rice area mapping was returned early in the year (late July), which is key for timely decision-making. Finally, the performance of the generalized paddy rice classification model, when applied in the sites of Haenam and Cheorwon, was compared to the performance of two equivalent models that were trained with locally sampled labels. The results were comparable and highlighted the success of the model’s generalization and its applicability to other regions.

Wage labor in rice cultivation areas near Lake Victoria in Western Kenya

Rice is now the most rapidly growing food commodity in sub-Saharan Africa. This growth is mainly driven by urbanization. There is substantial research on the wage labor dynamics in rice production in Asia, but in Africa, there is limited analysis of the labor used in rice cultivation-the attributes, numbers, and costs which make it difficult to understand the actual market, such as how products are procured. This study aims to fill this gap in the research by comparing wage labor factors in two rice cultivation areas in Kenya: Awach and Ahero. The role of wage labor in farm household management as well as in the economy of the areas is considered. The results, based on two surveys, show that, at the Awach small-scale scheme, the yield was low and the cultivation area small, generating profit per household of only about one-half that of the more large-scale Ahero scheme. High wage expenses at Awach put pressure on rice farming management because, although family labor was used for rice cultivation, additional labor was required for transplanting and weeding, incurring expenses. These were covered by sales of rice in the previous year or sales of livestock. In both areas, wage laborers were mostly people residing in the same area. In the case of Ahero, the scale of the scheme itself was large, and the hired laborers were unknown. However, in Awach, there was a high rate of hiring neighbors, and thus, wage labor costs could also be understood as a source of income for people in the area. Therefore, it can be inferred, in the case of Ahero, that there is a mechanism of wage labor based on economic principles, whereas in the case of Awach, small-scale production using family labor may be less efficient, but there is an additional concern with community principles. Key words: Rice cultivation, western Kenya, wage labor, economic principles, community principles.

Towards Sustainable Rice Production in Asia: The Role of Climatic Factors

Towards Sustainable Rice Production in Asia: The Role of Climatic Factors