Plant Gene and Trait 2025, Vol.16, No.3, 104-112 http://genbreedpublisher.com/index.php/pgt 105 multiple studies, this research seeks to provide a comprehensive understanding of the determinants of rice yield and offer actionable recommendations for policymakers, researchers, and farmers to achieve sustainable rice production. 2 Methodology 2.1 Data collection and criteria for inclusion The data for this study were collected from a comprehensive bibliographic search of research papers published between 2001 and 2022. The search focused on studies that investigated various techniques for improving rice yield, including quantitative trait loci (QTL) analysis, genome-wide association studies (GWAS), and field management practices. A total of 462 QTLs from 47 independent studies were retrieved, and 563 QTLs from 67 rice populations were analyzed for traits under water deficit conditions (Aloryi et al., 2022). Additionally, data on greenhouse gas emissions and yield responses to elevated CO2 and O3 concentrations were included (Ainsworth, 2008). Studies were selected based on their relevance to rice yield improvement, the robustness of their methodologies, and the availability of quantitative data. 2.2 Statistical approaches used for study The study employed several statistical techniques to synthesize data from multiple studies. QTL projection was performed using a reference map, and meta-QTL (MQTL) analysis was conducted to identify stable and robust QTLs with reduced confidence intervals (CI) (Khahani et al., 2021; Aloryi et al., 2022). For genome-wide association studies, meta-GWAS was used to detect significant loci affecting yield and its component traits (Su et al., 2021). Dose-response analysis was applied to assess the impact of high temperatures on rice yield and quality (Xiong et al., 2017). Additionally, statistical methods were used to evaluate the effects of various field management practices on greenhouse gas emissions and yield (Wang et al., 2012; Feng et al., 2013; Zhao et al., 2019). The results were synthesized to provide a comprehensive understanding of the genetic and environmental factors influencing rice yield. 2.3 Limitations and sources of bias in the study Several limitations and potential sources of bias were identified in this study. The heterogeneity of the studies included, such as differences in experimental conditions, genetic backgrounds, and environmental factors, could introduce variability in the results (Khahani et al., 2021; Su et al., 2021; Aloryi et al., 2022). Publication bias may have affected the selection of studies, as research with significant findings is more likely to be published. The reliance on reported data without access to raw data may limit the accuracy of the study. Additionally, the interaction between different field management practices and site-specific conditions was not always accounted for, which could influence the generalizability of the findings (Huang et al., 2015; Zhao et al., 2019). Despite these limitations, the study provides valuable insights into the techniques for improving rice yield and highlights areas for future research. 3 Overview of Global Rice Yield Improvement Techniques 3.1 Conventional breeding approaches Conventional breeding approaches have significantly contributed to the development of high-yielding rice varieties. The selection of high-yielding varieties involves identifying and propagating rice strains that exhibit superior yield potential under optimal conditions. This method has been a cornerstone of rice improvement strategies, particularly during the Green Revolution, which introduced semi-dwarf rice types that significantly increased yield potential (Khush, 2013). Hybrid rice technology has been another pivotal conventional breeding approach. By crossing two genetically diverse rice varieties, hybrid rice exhibits heterosis or hybrid vigor, resulting in higher yields compared to inbred varieties. Field experiments in China and Japan have demonstrated that the best recent Chinese hybrids have a yield potential about 10% higher than the best recent inbred cultivars in Japan (Horie et al., 2005). This technology has been instrumental in achieving yield gains and meeting the rising global demand for rice.
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