{"id":27908,"date":"2026-09-17T16:59:47","date_gmt":"2026-09-17T20:59:47","guid":{"rendered":"https:\/\/mmcereais.com.br\/2026\/arroz\/arroz-irrigado-frio-e-calor-podem-causar-esterilidade\/"},"modified":"2026-09-17T16:59:47","modified_gmt":"2026-09-17T20:59:47","slug":"arroz-irrigado-frio-e-calor-podem-causar-esterilidade","status":"publish","type":"post","link":"https:\/\/mmcereais.com.br\/en\/2026\/arroz\/arroz-irrigado-frio-e-calor-podem-causar-esterilidade\/","title":{"rendered":"Irrigated rice: cold and heat can cause sterility."},"content":{"rendered":"

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The flourishing of rice<\/a> Irrigated cultivation is one of the most sensitive phases of the crop cycle and can significantly impact productivity. Stress caused by cold, heat, lack of water, or inadequate management during this period can lead to spikelet sterility and reduce the number of filled grains per panicle.\n<\/p>\n

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Flowering occurs when the spikelets open and the ovule is fertilized by pollen. It is at this stage that it is determined how many of the grains formed will reach the harvest.<\/p>\n

Even a crop that has shown good development up to the booting stage can suffer losses due to a specific stress event. Temperature, water availability, irrigation management, and nutritional balance are among the factors that can affect flower fertility.<\/p>\n

Irrigated rice is a warm-climate crop, but it is sensitive to extreme temperatures during the reproductive phase. The critical period begins a few days before panicle emergence, at the booting stage, and extends until the end of flowering.<\/p>\n

During this period, pollen development, flower opening, and fertilization depend on suitable air and water temperature conditions. Maintaining a stable water level and a good supply of nutrients are also important, as is the health of the plants.<\/p>\n

Rice flowering typically occurs in the morning, when the spikelets remain open for a few hours. Before anthesis, pollen development takes place within the panicle.<\/p>\n

According to data presented in the technical material, intense cold or excessive heat at this stage can impair pollen viability. At anthesis, when the spikelet opens, the anthers are exposed, and the pollen is released, adequate temperature and humidity conditions are necessary for germination on the stigma and growth into the ovule.<\/p>\n

After fertilization, the formation of the embryo and endosperm begins. Severe stress at this stage can cause the death of the newly formed embryo and result in empty spikelets.<\/p>\n

Sterility occurs when one or more of these stages are impaired. Causes include low air and water temperatures during pollen formation and anthesis, as well as excessively high temperatures during flowering, which can cause stigma desiccation and render the pollen unviable.<\/p>\n

Water stress near the booting and flowering stages also increases the risk. Abrupt variations in water availability can affect the plant, while nutritional imbalances, especially excess or lack of nitrogen and deficiency of potassium and sulfur, can also compromise fertility.\n<\/p>\n

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The consequence is directly reflected in the yield. Sterility reduces the number of filled grains per panicle, one of the components of rice's productive potential.<\/p>\n

Even when the crop exhibits good tillering and large panicles, a high number of empty spikelets can compromise final productivity. In situations of intense heat stress during flowering, sterility can reach levels capable of causing productivity reductions of tens of percentage points.<\/p>\n

The impact can also extend to the processing stage. A higher proportion of full and shriveled grains can hinder harvest planning and affect industrial quality, including reducing the yield of whole grains.<\/p>\n

Prevention begins before sowing, especially between June and September, a period in which the crop is planned, cultivars are chosen, the planting season is determined, and the irrigation system is established.<\/p>\n

Planting planning should aim to position flowering during a phase of the cycle with a lower probability of intense cold during the early morning hours or extreme heat waves. In regions subject to late frosts, the recommendation presented in the material is to avoid the booting and flowering stages coinciding with historically colder periods.<\/p>\n

Historical climate data and seasonal forecasts can be used to adjust the planting season, always within the window recommended by research institutions.<\/p>\n

The choice of cultivar also affects the crop's exposure to risks. The material recommends considering cycles appropriate to the region and sowing season, as well as the sensitivity of each cultivar to cold and heat during the reproductive phase.<\/p>\n

The uniformity of flowering should also be observed. Materials with more concentrated flowering can facilitate management and assessment of climate risks in the crop.<\/p>\n

Irrigation is another point of attention. The system must be able to maintain a stable water level during the critical period, which runs from the booting stage to the end of flowering.<\/p>\n

It is also necessary to assess the availability of water in the reservoir to avoid shortages precisely during the reproductive phase. Under certain conditions, adjustments to the water flow may be considered to reduce abrupt variations in water and air temperature near the canopy, always with technical support.<\/p>\n

Nutritional management should aim for balance. Soil analysis and, when possible, foliar analysis help adjust base and topdressing fertilization, avoiding deficiencies and excesses, especially of nitrogen.<\/p>\n

The final application of nitrogen as a top dressing should be planned to ensure supply during the reproductive phase, without excesses that could promote lodging or delay maturation. The management of potassium, sulfur, and micronutrients related to floral fertility should also consider technical recommendations and analysis results.<\/p>\n

During flowering, maintaining a constant water level becomes important. The material recommends keeping it constant from a few days before the shoot begins to set until the end of the flowering phase, preventing soil exposure and drying out of the area.<\/p>\n

Sudden variations in water level should be avoided because they can generate stress, impair nutrient absorption, and abruptly alter the water temperature. During cold periods, a stable water level helps to mitigate temperature drops in the rhizosphere. During heat waves, it helps to dampen temperature spikes near the plants.<\/p>\n

Nitrogen also requires attention during the growing cycle. The distribution of applications must be appropriate to the cultivar's cycle, ensuring supply during the reproductive phase without excess near flowering.<\/p>\n

The material advises avoiding concentrated doses too close to the booting stage in unstable weather conditions. Excess nitrogen can make the plant more susceptible to lodging and heat stress.<\/p>\n

Management should also consider the area's history, expected productivity, and official recommendations based on soil analysis and, when available, regional research recommendations.<\/p>\n

Protecting crops from other stress factors is also part of prevention. Weeds compete for water and nutrients and should be managed, especially near the reproductive period.<\/p>\n

Monitoring for leaf and panicle diseases is also necessary, as these problems can compromise grain filling after flowering and further reduce the number of filled grains.<\/p>\n

Applications of agrochemicals with a risk of phytotoxicity during the booting and flowering stages should be avoided. The material recommends giving preference to selective products and following specific guidelines for this stage.<\/p>\n

Monitoring the weather throughout the cycle allows for proactive management decisions. As the short- and medium-term forecast approaches the booting stage, minor adjustments to operations, such as blade management or topdressing applications, can be evaluated in light of the possibility of intense cold or heat waves.\n<\/p>\n

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When intense cold is forecast precisely during the flowering period, the material recommends evaluating with the responsible technician the possibility of discreetly bringing forward or postponing certain practices that could alter the pace of development, always with caution and technical support.<\/p>\n

After flowering, monitoring continues. During grain filling, the percentage of empty spikelets can be observed at different points in the field, allowing for the recording of possible relationships with variations in terrain, irrigation, or soil.<\/p>\n

This information can be used to improve the planning of subsequent crops, including the choice of cultivars, the sowing season, and irrigation management in areas with a higher incidence of barrenness.<\/p>\n

Recording the dates of booting and flowering, weather conditions, and management practices also helps to create a unique history for the property.<\/p>\n

The strategy to reduce sterility during rice flowering, therefore, begins with crop planning and continues throughout the reproductive period. The combination of appropriate sowing time and cultivar selection, water stability, balanced nutrition, and monitoring of climate, pests, and diseases aims to reduce stress precisely during the most sensitive phase of the crop.<\/p>\n

Recommendations regarding fertilizer doses, planting timing adjustments, and cultivar selection should be determined with the support of an agricultural engineer, considering soil analyses, area history, and official research recommendations.<\/p>\n<\/p><\/div>\n

THE MM Cereais<\/strong> It works with the best rice grains on the market and also keeps you up-to-date on the latest news and analysis about agribusiness.
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