Study indicates the best dates to plant beans in Goiás

Bean producers in Goiás now have another tool to reduce the risk of losses due to climate. A study conducted by researchers from Embrapa, in partnership with the Federal University of Goiás (UFG), identified the ideal planting windows for dry beans in 28 municipalities in the state. Based on simulations performed with an advanced computer model, the scientists discovered that the right time to sow can significantly change crop yields, depending on the location. The study used climate data and data from the crop's genetic improvement program and complements information from the Agricultural Climate Risk Zoning (Zarc) for beans in Goiás.

Scientists used historical series of climate data to feed the CSM-CropGro-Dry Bean model, used to simulate bean development and created by researchers from the University of Florida in the United States, in collaboration with the International Center for Tropical Agriculture (CIAT) in Colombia. CSM-CropGro-Dry Bean is a computer program capable of integrating variables related to the sowing location, such as climate and soil, cultivar characteristics and crop management. The result is the indication of sowing windows in which there is a lower risk of exposure, throughout the crop cycle, to adverse weather conditions and, consequently, the achievement of better yields.

In Goiás, the sowing of dry beans coincides with the beginning of the rainy season in late October and can last until December. However, it is common for rainfall distribution to vary throughout the state. Therefore, defining sowing windows and periods with greater water availability helps to minimize the drop in crop productivity.

Scientists simulated productivity with the CSM-CropGro-Dry Bean and estimated climate risk for 28 municipalities representative of dry bean production in Goiás. Risk was assessed based on the selection of eight different sowing dates, one every ten days, between the end of October and December.

In most municipalities on the eastern border of the state of Goiás, there was an increase in yield losses due to delayed sowing. In these cases, it is recommended that beans be sown at the beginning of the rainy season, between mid-October (days 20 to 30) and early November (day 10). For municipalities located further west in the state, it is recommended that sowing occur at the end of November (days 20 to 30) and in December (days 10, 20 and 30), since yield losses decrease as sowing is carried out later.

Results vary depending on the location of each municipality

Municipalities with a tendency for productivity to drop increases with delay in sowing:

1. Cold Water of Goiás, 3. Headwaters, 5. Campo Alegre of Goiás, 6. Catalan, 8. Crystalline, 9. Flowers of Goiás, 10. Formosa, 14. Leopold of Bulhões, 15. Luziânia, 21. Planaltina, 24.

Municipalities with a tendency for productivity to decline with delay in sowing: 2. Alto Paraíso de Goiás, 4. Caiapônia, 7. Chapadão do Céu, 11. Gameleira de Goiás, 12. Ipameri, 13. Jataí, 16. Mineiros, 17. Montividiu, 18. Niquelândia, 19. Padre Bernardo, 20. Perolândia, 22. Rio Verde and 23. Santo Antônio do Descoberto.

According to one of the study coordinators, Alexandre Heinemann, a researcher at Embrapa Arroz e Feijão (GO), the difference is caused by the variation in rainfall distribution across the state. “The rainy season begins in October and continues throughout the summer in the state of Goiás, but the decrease gradually progresses over the months to the northwest. That is why the difference highlighted by the research exists,” says Heinemann.

The irregular distribution of rainfall across the state can harm crop productivity. Researcher Silvando Carlos da Silva, who also participated in the study, highlights the importance of the impact of reduced water on plants. “Bean plants are more susceptible to water deficits during the reproductive phase. When the water supply is reduced, especially during the flowering period, there is a risk of reduced plant height, pod size, number of pods and number of seeds per pod, which directly affects crop yield,” explains Silva. He emphasizes that for beans to reach their full yield potential, air temperatures must be at least 12°C, at most 30°C and at an optimum level of around 21°C.

Computer simulation

The CSM-CropGro-Dry Bean model helps to gain more knowledge about the responses of bean crops in interaction with the environment, as it provides results that involve a complexity of physical, chemical and biological processes.

It is a tool that allows the study and understanding of cultivated systems, estimating crop performance under different conditions. According to Heinemann, it is a form of predictive modeling based on the use of big data (large banks of information collected over time). He commented that the difference brought about in the study conducted by Embrapa and UFG was precisely the approach to interpreting the data obtained by CSM-CropGro-Dry bean.

Heinemann noted that functional data analysis (FDA) was used, a set of techniques to summarize the properties of a time series through mathematical functions and statistics. “By applying the set of functional data analysis techniques, we were successful in determining sowing dates with lower climate risk,” Heinemann said.

The researcher also clarifies that CSM-CropGro-Dry Bean does not replace Zarc, but adds to it and provides a new type of approach to knowledge about cultivation, allowing the establishment of proactive risk management strategies that optimize resource allocation and increase agricultural resilience in the face of possible climatic adversities.