The International Rice Research Institute (IRRI) is an international agricultural research and training organization with its headquarters in Los Baños, Laguna in the Philippines, and offices in seventeen countries. IRRI is known for its work in developing rice varieties that contributed to the Green Revolution in the 1960s which preempted the famine in Asia.The Institute, established in 1960 aims to reduce poverty and hunger, improve the health of rice farmers and consumers, and ensure environmental sustainability of rice farming. It advances its mission through collaborative research, partnerships, and the strengthening of the national agricultural research and extension systems of the countries IRRI works in.IRRI is one of 15 agricultural research centers in the world that form the CGIAR Consortium of International Agricultural Research Centers, a global partnership of organizations engaged in research on food security. It is also the largest non-profit agricultural research center in Asia.
Mid-season rice in the Yangtze River basin was studied to analyze the effects of high-temperature stress during flowering on yield and seed setting rate, using ORYZA(v3) model simulation data (1981–2019). Results indicated that: (1) Under varying high-temperature durations during flowering, rice yield and seed setting rate were less negatively impacted in coastal Jiangsu. (2) In the mid-season rice-producing area of the Yangtze basin, long-duration (≥8 days) low-intensity (≤38 ℃) and short-duration (≤3 days) high-intensity (≥41 ℃) heat stress during flowering induced similar yield and seed setting rate reductions. (3) Yield and seed setting rate reduction trends plateaued when high-temperature duration at anthesis reached 8 days; durations below 2 days showed no significant differential effects on reduction percentages across intensities. Given these findings, under future warming scenarios, extremely high-temperature events in the rice-producing region of the Yangtze River Basin are expected to increase in frequency and persistence. Proactive measures are crucial for mitigating sequential high-temperature events during rice flowering, thereby ensuring stable and high yields in mid-season rice-producing areas of the Yangtze Basin.
Rice (Oryza sativa) is one of the world’s most important cereal crops, contributing to food and financial security, particularly in developing countries. High temperature due to climate change seriously threatens sustainable rice production. Rice crops are adversely affected by heat stress at the morphological, physiological, and molecular levels, resulting in reduced yield and poor grain quality. Rice is highly sensitive to heat during the reproductive phase, causing pollen sterility, impaired pollen dehiscence, pollen germination, and tube growth, ultimately drastically reducing spikelet sterility and yield. High temperature also promotes the accumulation of reactive oxygen species in plant cells, resulting in multiple adverse effects, including damage to chloroplasts and cell membranes, inactivation of photosystems, reduced Rubisco activity, and impaired production of photoassimilates. In this review, we have synthesized the current knowledge on the effects of heat stress on rice and summarized QTLs, genes, and regulatory pathways underlying thermotolerance. We further evaluate conventional breeding, transgenics, and diverse omics-based strategies to breed high-yielding, heat-tolerant rice varieties. The precise molecular insights gained through various omics approaches are expected to advance our understanding of the intricate nature of heat stress tolerance in rice. Additionally, we highlight the emerging roles of microbiome, high-throughput phenotyping technologies, and artificial intelligence as promising tools for accelerating the development of heat-resilient rice.
Flooding stress is a major adverse condition during the emergence period of direct-seeded rice. This study investigated the use of wood vinegar as a seed soaking treatment to enhance rice seedling rates under flooding stress, exploring both the methodology and physiological mechanisms involved. The optimal seed soaking concentration was determined through a gradient experiment, followed by a multi-cultivar validation test. The physiological mechanism of wood vinegar soaking on seedling emergence was analyzed by measuring the electrical conductivity of the flooding water, the changes in starch and soluble sugar contents in the grains and sprouts, and the dynamics of α-amylase activity and antioxidant-related enzyme activities in the sprouts. The results showed that soaking rice seeds in a wood vinegar solution at a low concentration significantly enhanced the emergence of rice seedlings under flooding conditions, with a 100-fold dilution having the most pronounced effect, increasing seedling rates by 50.6%–60.0%. Further analysis indicated that wood vinegar treatment enhanced seedling establishment by inducing a significant increase in α-amylase activity, leading to a 74.9%–213.6% increase in soluble sugar content in the sprouts during 2–8 d after flooding stress compared with the control. Additionally, the treatment increased superoxide dismutase and peroxidase activities in the sprouts, mitigating lipid peroxidation of the cell membranes, and notably lower water electrical conductivity was observed in wood vinegar-treated seeds compared with the control. In conclusion, soaking rice seeds in a 100-fold diluted wood vinegar solution improves rice seedling rates under flooding stress by mitigating oxidative damage and maintaining energy supply. This approach is valuable for developing cost-effective seed treatment technologies and offering novel strategies to improve seedling rates and uniformity of direct-seeded rice under flooding conditions.
Boosting crop photosynthesis holds promise for meeting the needs of a growing population in a warming climate. However, improving photosynthesis with crop biotechnology is a new prospect for farmers and other key agrifood stakeholders, who will determine the success of such pioneering plant breeding initiatives. We conducted focus groups with 62 participants in four countries to understand farmer and agrifood stakeholder perspectives towards the aim of boosting photosynthesis through biotechnology in rice and potato, two of the world's most important crops. We found farmers were positive towards the benefits of boosting photosynthesis, although the relative importance of improving yield was debated - water and radiation use efficiency were less contested and linked to more sustainable agriculture. Farmer concerns centered on balancing the competing agronomic and market demands that new varieties would bring. Farmers in the low-income countries had few concerns about the use of biotechnology and anchored their understanding in existing biotechnology crops, such as Golden Rice in the Philippines and Bt Brinjal in Bangladesh. Farmers in Europe and industry stakeholders were more apprehensive about biotechnology crops for several reasons that were rooted in the perceived opinion of consumers and supermarkets towards biotechnology.
Extreme temperature events associated with climate change have led to significant declines in rice production, particularly when they occur during reproductive growth stages. However, existing models lack the ability to capture the distinct effects of sustained versus episodic low-temperature stress. In this study, a two-year temperature-controlled experiment was conducted with two temperature levels to compare the impacts of individual and combined low-temperature stress at booting (BS), flowering (FS), and combined (BS + FS) stages on rice yield and its components. Low-temperature stress occurring at booting and combined stages significantly reduced spikelet fertility in the upper spike and grain number in the lower spike, whereas it showed a stronger effect on the spikelet fertility in the lower spike at flowering stage. Under the same cooling degree-days (CDD), continuous low temperature at 12 degrees C for 8 days at booting caused the largest yield loss (55.3 %), compared with 15.5 % at flowering and 39.3 % under the combined treatment, suggesting that low-temperature stress exerts different cumulative effects across booting and flowering stages. We refined the ORYZA yield formation algorithms using these experimental insights, enabling the model to account for both intermittent low-temperature events and combined stress across booting and flowering stages, thereby better reflecting the conditions observed in rice production. The improved model substantially enhanced simulation accuracy (RMSE reduced from 7.18 to 2.05 g plant-1; D index increased from 0.72 to 0.93), and was further validated against historical low-temperature events at multiple sites in Northeast China. This improvement enhances the reliability of rice yield predictions under field low-temperature scenarios, thereby supporting climate risk assessment and cold-tolerance breeding.
