Falling temperatures increase the vulnerability of second-crop fields in the Center-South region, warns Inmet.

Adverse weather conditions have significantly impacted the progress of the second grain crop in the states of Paraná and Mato Grosso do Sul. In some regions, the delay in harvesting compromised the ideal planting window for subsequent crops, increasing the risks associated with reduced rainfall and a higher probability of incursions of cold air masses, which normally advance over the region throughout May. During the planting of corn and bean crops, a reduction in rainfall volumes was observed, causing initial problems in crop development, mainly in western Paraná and southern Mato Grosso do Sul. Both crops entered critical development phases throughout April and early May, depending on the growing region, being strongly impacted by water scarcity precisely during the period of greatest water demand by the plants. This condition has already resulted in significant losses, even with the improvement in rainfall observed between the end of April and the beginning of May. Currently, weather forecasts indicate the advance of an intense mass of polar air over the Southern Region, southern São Paulo and Mato Grosso do Sul. The scenario points to a sharp decline in temperatures, favoring the occurrence of frosts in much of the Southern Region of Brazil. This situation represents a high risk for summer crops, such as corn and beans, which are in critical stages of development in the states of Paraná, Mato Grosso do Sul and São Paulo. In this context, the economic importance of the regional center of Ponta Grossa (PR) stands out, which has approximately 33,000 hectares cultivated with second-crop corn. According to the Department of Rural Economy of Paraná (DERAL), approximately 95% of this area is in phases more sensitive to thermal stress, with 25% in flowering and 70% in fruiting. Given this scenario, the forecast of falling minimum temperatures in the coming days, with a value around 3.6 °C on Tuesday (12), increases concern about possible impacts on flowering and grain filling. These conditions can cause pollination failures, reduced grain formation, and consequently, decreased productivity. Furthermore, the prolonged drought period between April 10th and 26th, shown in Figure 1, contributed to increasing the plants' vulnerability to heat stress. The combination of early water deficit and a sudden drop in temperature intensifies the risk of severe crop damage, especially in areas more susceptible to frost. For bean crops, which are even more sensitive to low temperatures, flower abortion and reduced pod formation may occur. During grain filling, frost can cause wrinkling, as well as a reduction in grain size and weight. On the other hand, winter crops in the planting or early development phase, such as wheat, oats, canola, and pastures, should not experience significant negative impacts at this time. Weather Forecast: The forecast for the coming days indicates the passage of a cold front over the Southern Region, favoring the occurrence of intense rainfall and severe weather conditions in areas of southwestern and south-central Paraná, as well as northern Santa Catarina, with accumulations that could exceed 80 mm. Temperatures are expected to remain low in much of the Southern Region, especially in southern Rio Grande do Sul, western Santa Catarina and Paraná, as well as the extreme south of Mato Grosso do Sul. The cold air mass will continue to act throughout the end of the week, particularly in areas of south-central Paraná and the mountainous region of Santa Catarina, where minimum temperatures may fall below 8 °C, with values below 2 °C in higher areas. This scenario of intense cold, associated with the possibility of frost in higher altitude areas of Paraná and Santa Catarina, increases the risk of impacts on crops that are in more sensitive stages of development. This situation reinforces the need for careful planning of agricultural activities in the region, recommending continuous monitoring of meteorological updates to support decision-making in crop management, reduce operational risks, and optimize the planning of field operations.

This text was translated by machine from Brazilian Portuguese.