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Farmers’ perceptions of improved rice varieties represent a critical initial step in their adoption as climate change adaptation strategies. This study examined farmers’ perceptions by integrating on-farm adaptive research, which compared the agronomic performance of rice varieties, with participatory approaches to capture farmers’ evaluation of improved varieties. A total of 81 farmers from climate-affected areas of Batang Regency were purposively selected as respondents. Data was collected through structured interviews and questionnaires administered during the evaluation of field demonstrations. Farmers’ perception levels were assessed using a Guttman scale and classified into three categories: high, medium, and low. Logistic regression analysis was subsequently employed to examine the relationship between farmers’ socio-demographic characteristics and their acceptance of improved rice varieties. The results indicate that, overall, farmers exhibited a low perception of improved rice varieties. Among the evaluated opinions, Inpari 32 HDB received the highest perception scores across all agronomic attributes. The regression results show that farm size and age significantly influence variety acceptance. The odds ratio for farm size (0.117) suggests that each additional hectare of cultivated land area reduces the likelihood of adopting improved rice varieties by approximately 88.3%, holding other factors constant. In contrast, the odds ratio for age (1.080) indicates that each additional year of age increases the probability of adoption by about 8%.

Abstract Rice fields are a major producer of methane, a strong greenhouse gas. However, identifying genetic variation in methane emissions among rice varieties remains challenging. This study applied association rule mining to detect key rice root morphological and anatomical traits influencing methane emissions, validated using a support vector machine. We report models which accurately classified high and low methane-emitting varieties with 98% (morphological) and 94% (anatomical) accuracy. These models effectively distinguished methane emission categories based on intrinsic trait patterns. Machine learning analysis highlighted the top 10 morphological and anatomical traits associated with methane emission levels. High methane-emitting varieties were characterized by lower middle root porosity, base root porosity, average root porosity, root diameter (RDia), and higher S-type lateral root length. Conversely, low methane-emitting varieties exhibited lower root number, tiller number, root dry weight, leaf number, and higher RDia. Anatomically, high methane-emitting varieties showed reduced lacunae number, total stele area, mean metaxylem size, metaxylem number, and metaxylem vessel area. Low methane-emitting varieties, in contrast, had higher percent aerenchyma, total stele area, ratio of total cortical area to root cross-section area, ratio of stele to root cross-section area, and aerenchyma area. The results suggest that the rhizosphere oxygenation role of root porosity and aerenchyma might predominate over the methane transport role.

Selection of varieties and number of seedlings per hole in rice plants is closely related to the shape of canopy, the rate of plant growth and the age of plant which determine the ability of plants to intercept and absorb solar radiation intensity. This research aimed to improve the Radiation Use Efficiency of rice by selecting plant canopies based on varieties and number of seeds per hole. Research was conducted from November 2015 to May 2016, in Landak Regency, West Kalimantan. A Split Plot Design with three replications was adopted to evaluate three varieties (Sembada-168, Inpari-30, and local varieties) as main plot, and the number of seedlings per planting hole (one, three, five, and seven seedlings per planting hole) as sub plot. Result showed that there was no interaction between varieties and the number of seedlings per hole to Radiation Use Efficiency (RUE) on rice. RUE on local variety was lower than Sembada-168 and Inpari-30. One seedling per hole had higher RUE than seven seeds with value of 3.36 and 2.17 % respectively. The number of seedlings showed that RUE of one and three seedlings per hole were higher than seven seedlings per hole.

High-yielding varieties developed in the 1960s and 1970s at the International Rice Research Institute (IRRI) and elsewhere benefited farmers and the public, ultimately increasing yields and reducing the cost of rice to consumers. Most of these varieties, however, did not have the optimum cooking quality that was possessed by many of the traditional varieties they replaced. In 1985, the IRRI-developed indica variety IR64 was released in the Philippines. In addition to its high yield, early maturity and disease resistance, it had excellent cooking quality, matching that of the best varieties available. These merits resulted in its rapid spread and cultivation on over 10 million ha in the two decades after it was released. It has intermediate amylose content and gelatinization temperature, and good taste. It is resistant to blast and bacterial blight diseases, and to brown planthopper. Because of its success as a variety, it has been used extensively in scientific studies and has been well-characterized genetically. Many valuable genes have been introduced into IR64 through backcross breeding and it has been used in thousands of crosses. Its area of cultivation has declined in the past 10 years, but it has been replaced by a new generation of high-quality varieties that are mostly its progeny or relatives. Continued basic studies on IR64 and related varieties should help in unraveling the complex genetic control of yield and other desirable traits that are prized by rice farmers and consumers.

Genetic diversity is a useful resource for crop improvement. In this study, a total of 28 rice genotypes were screened to isolate potential salt-tolerant genotypes at the seedling stage using hydroponic system. Different morpho-physiological indicators were used to classify tolerant and susceptible genotypes and biochemical determinants were dissected to clarify the underlying tolerance mechanism. Rice seedling were treated with two salinity levels (EC-1.1 dSm‒1 (control) and EC-7 dSm‒1) for 18 days. Salt stress resulted in significant decrease of growth and physiological traits in all genotypes; however, the lowest reduction was observed in some salt-tolerant genotypes namely Ghunsi, Nonabokra, Hogla, Holdegotal, Vusieri, and Kanchon. Cluster analysis considering percent reduction of growth parameters categorized the genotypes into four main sub-clusters and importantly, the salt-tolerant landraces were placed in the same cluster (cluster-II) with salt-tolerant check genotypes. The results of principle component analyses also demonstrated highly salt-tolerant genotypes were Vusieri > Nonabokra > Ghunsi > Hogla > Holdegotal > Kanchon. To explore the potential biochemical basis of salt stress tolerance, three tolerant genotypes were further characterized along with a salt-sensitive genotype. The higher K+/Na+ ratios noted for all salt-tolerant landraces thus indicating that the K+/Na+ ratio serves as a reliable indicator of salt tolerance in rice. The higher increment of proline content, catalase, ascorbate peroxidase activities, and comparatively lower accumulation of H2O2 and MDA were reported in salt-tolerant landraces as compared with salt-sensitive genotype. Therefore, these landraces could be utilized as promising genotypes as a source of salt-tolerant parents in the hybridization program for the development of high-yielding salt-tolerant rice variety as well as in isolating salt-tolerant genes.

Intermittent irrigation can save water use in rice cultivation, which is essential, especially during the dry season. This study aims to improve the physiology of the growth and yield of rice in various varieties by applying intermittent irrigation. The research was conducted from February to June 2019 in the experimental field of the Faculty of Agriculture, Universitas Muhammadiyah Yogyakarta. The research used a factorial experimental method 3 x 4 strip plots arranged in a Completely Randomized Block Design with three replications. The factor I rice varieties consist of Cempo Merah, Inpari 23, Sintanur, and Inpari 42. Factor II is the irrigation system consisting of continuous flooding, ten days of inundation, five days of drying, seven days of inundation, and three days of drying. There is an interaction between types of irrigation and rice varieties on the number of tillers. In Ten-day watering five-day drying, Sintanur and Inpari 42 variety produce more tillers than Inpari 23. On Seven days watering five-day drying, the Inpari 42 variety produces more tillers than Inpari 23. There are the differences in the responses of various rice varieties to the Specific Leaf Weight and yield. Specific Leaf Weight rice Cempo Merah varieties are higher than, Inpari 23, Sintanur and Inpari 42. Rice yield of Inpari 42 variety is higher than Cempo Merah, Inpari 23, and Sintanur varieties. Roots with watering seven days watering, three days of drying is longer than Ten-day watering five-day drying. Roots with watering Ten-day watering five-day drying is longer than conventional.

Rice bran oil (RBO) is increasingly valued for its bioactive constituents and associated health benefits. This study presents a comprehensive comparative analysis of RBOs derived from purple (PRBO), red (RRBO), and white (WRBO) rice bran, focusing on their physicochemical properties, fatty-acid profiles, bioactive components, antioxidant activity, oxidative stability, and lipidomics. Our results demonstrate that PRBO consistently exhibited a more favorable fatty-acid composition, characterized by a higher proportion of unsaturated fatty acids and significantly greater concentrations of bioactive compounds (including tocopherols/tocotrienols, γ-oryzanol, phytosterols, and squalene). Accordingly, PRBO showed the highest radical-scavenging activity and storage oxidative stability, followed by RRBO and WRBO. Additionally, untargeted lipidomics using UPLC–MS–MS identified 2908 lipid species spanning 57 subclasses and revealed distinct variety-specific lipid signatures. PRBO was uniquely enriched in lipid species such as ceramide phosphate (CerP) and monogalactosyldiacylglycerol (MGDG). RRBO was characterized by a distinct abundance of sitosteryl esters (SiE), phosphatidic acid (PA), and cardiolipin (CL), while WRBO was distinguished by phosphatidylethanol (PEt), lysodimethylphosphatidylethanolamine (LdMePE), and sphingomyelin (SM). Overall, PRBO possessed not only a broader repertoire of lipid species but also higher relative abundances of nutritionally significant lipids. These results enable quality evaluation and varietal authentication of colored RBOs and guide their targeted use in health-oriented foods and nutritional interventions.

Rice is globally a major food crop and its production has progressively been affected by various types of abiotic stresses especially drought, flooding, salinity, heat and cold in most of the cultivable rice ecosystems. The incidence, intensity and duration of these stresses are anticipated to aggravate due to climate change consequences, demanding resilient yields in these situations to be essential. Present paper deals with reviewing various types of abiotic stresses and their mitigation strategies for enhancing and stabilizing rice production in stress prone areas. Review of available literature pertaining to the study area has been used as research methodology for this paper. The available literature suggests that stress-tolerant varieties can serve as the most viable strategy to contribute in coping with the problem of abiotic stresses. Although, good progress has been made in the development of stress-tolerant rice varieties (STRVs) and incessant efforts are being made to spread these varieties in target areas, adoption by farmers is yet to meet expectations. Advantage, affordability, awareness and availability are the main factors responsible for adopting of any technology. The adoption of stress-tolerant varieties has not reached its potential, predominantly due to the lack of awareness and non-availability of seeds amongst farmers. Strategic and intentional collaborations should be ensured for scaling the sustainable delivery and diffusion of STRVs. A promotional roadmap that ensures the linkages between private and public seed sectors remains the key factor for its successful adoption. Similarly, strengthening of formal, informal and semi-formal seed systems is crucial to accelerate the dissemination of these varieties. There is an imperative need to create strategic plans for the development of varieties possessing multiple stress tolerance. Significant investments for sustainability of rice production in stress prone areas form the essential component of long-term agricultural development. The sooner these investments and strategies are accomplished, the greater the gains are expected.

In this study, three japonica rice varieties—Nanjing 9108, Jiahua 1 and Wuyunjing 29—were supplied with different levels of nano-foliar selenium fertilizers (0, 40 and 80 kg Se ha−1) under field conditions. Their rice yield and absorption, accumulation, transportation and utilization of selenium were studied to find suitable selenium-rich rice cultivars and optimal selenium supply levels, while providing references for the development of selenium-rich rice. On an average basis, the Nanjing 9108, Jiahua 1 and Wuyunjing 29 yielded 8755 ± 190, 8200 ± 317 and 9098 ± 72.7 kg ha−1, respectively. The selenium content in polished rice of the three rice varieties is between 0.210 and 0.933 mg kg−1. When 40 g Se ha−1 nano-selenium fertilizer was used, the selenium accumulation in the shoots of Nanjing 9108, Jiahua 1 and Wuyunjing 29 was, respectively, 11.4 g Se ha−1, 12.3 g Se ha−1 and 12.2 g Se ha−1, and when 80 g Se ha−1 selenium fertilizer was applied, the total selenium accumulation of three rice varieties was, respectively, 2.45, 1.75 and 2.40 times that of 40 g Se ha−1 selenium fertilizer. No evident diversity was observed in the selenium transport coefficient and the apparent utilization rate of selenium among the three varieties. The three rice varieties in this experiment had a strong selenium enrichment capacity, and they could be planted as selenium-enriched and high-yield rice varieties. Further, the amount of selenium fertilizer should not exceed 40 g Se ha−1.

Rhizosphere microbiomes and metabolomes are influenced by host genotype and developmental stage. However, there has been limited research that simultaneously profiles the rhizosphere microbiome and metabolism of rice across different genotypes and developmental stages. Furthermore, the interactions between rhizosphere microbiomes and metabolism in various plant genotypes and developmental stages are not well understood. Here, we investigated the diversity and composition of rhizosphere microbial community and metabolism across three hybrid rice varieties and their respective parent lines during three developmental stages (tillering, heading, and mature) using amplicon sequencing and untargeted metabolomics analyses. Plant developmental stages and genotypes significantly influence the rhizosphere microbiome and metabolome, with the impact of developmental stages being more pronounced. The composition of microbial communities and metabolites in the rhizosphere exhibited significant differences between the tillering stage and other developmental stages, with these differences becoming less distinct as the growth period continued. Hybrid rice displayed heterosis characteristics in their rhizosphere microorganisms compared to their parent varieties, as reflected by the significant enrichment of microbial species and the enhanced potential for microbial interactions within the co-occurrence network. Moreover, the differential microorganisms between the tillering and heading stages showed significant correlations with differential metabolites and soil chemical properties, including total phosphorus (TP), available phosphorus (AP), and nitrate nitrogen (NN). Taken together, this study contributes to our understanding of plant-microbiota-metabolome associations and provides a foundation for developing beneficial plant microbiomes and compounds to promote sustainable agricultural production.