Research defines best period for planting irrigated rice in TO

A survey developed by Embrapa defined that the most favorable period for sowing irrigated rice in the state of Tocantins is the interval between October 1st and November 20th. That window corresponds to the time of lowest climate risk for the crop, a result registered in the article Climatic risk and sowing period for irrigated rice in Tocantins, published in the Agri-Environmental Sciences Magazine, from the State University of Tocantins (Unitins). This information is important because the Determining the best planting time is one of the most important management practices. strategies to avoid losses in the field and achieve a profitable harvest with greater productivity.

The research covered the floodplain environment tropical areas of the Tocantins-Araguaia river valley, involving five municipalities rice producers: Dueré, Cristalândia, Lagoa da Confusao, Formoso do Araguaia and Pium.

For the study, the software computer called ORYZAv3, developed for work applications scientific. It is software that simulates growth, development and rice crop productivity and is supplied with data on soil, climate (historical series of daily precipitation, temperature and solar radiation data global), management practices and cultivation characteristics. In this case, the source information to validate this system was the series of experimental data from field of Embrapa's tropical irrigated rice improvement program and service InfoClima. To apply simulations within the model ORYZAv3, the impact on the agronomic behavior of the cultivar BRS Catiana, material considered as reference in this study and widely planted in the region.

Embrapa Arroz e Feijão researcher Alexandre Heinemann, one of the coordinators of the work, highlighted that sowing at a favorable time is essential in reducing the risk climatic, as it increases the chance that the plant's critical phases will not coincide with the occurrence of adverse climatic factors. In this sense, he considered that, for the region studied, plantings after November 20th, December, as well as those later, in January, are not recommended. “The ideal period is from the beginning of October to November 20th. This period presents greater probability of high productivity, due to cooler climatic conditions favorable to the development of rice cultivation,” he stated.

Heinemann commented that the best season of seeding was established in the research through the relationship between elements climatic conditions and their effect on plant physiology at each stage of plant development in the field. For example, two essential components: solar radiation and air temperature impact reducing or increasing the productivity. “During the rice grain filling phase, solar radiation adequate temperature is reached in the Tocantins floodplains between January and February. In that period, air temperatures are also higher, which is advantageous, as reduces disease pressure on the grains and facilitates the drying process in the end of farming. For this situation, sowing must be carried out between October and November 20th”, advises the scientist.

Furthermore, there is another favorable factor for sowing during this period. According to the researcher, this seeding window provides the occurrence of lower values ​​of minimum air temperature in the phase vegetative growth of the crop, when compared to other planting times. That brings less energy expenditure on plant maintenance, due to less respiration night vegetable.

Result combined with practice

Heinemann drew attention to another issue associated with the sowing period. Knowledge of how it works of the local production system is another component to be considered. According to him, In the Tocantins-Araguaia river valley, irrigated rice, in a large part of the areas, is succeeded by soybean cultivation for seed production, conducted with sub-irrigation. The soybean sowing window in tropical floodplains begins on April 20th and continues until May 31st. Considering that soil preparation for soybeans must be done well in advance of sowing to allow for decomposition of rice straw, this implies that the cereal harvest is completed by the end of March, and may extend until the beginning of April. According to the researcher, this practice reinforces the indication that sowing of irrigated rice occurs within the period recommended by the study, since the The cereal crop cycle generally lasts 120 days, which provides the grain harvest in the months of February and March, without disturbing the soybeans.

Tocantins is the third largest producer

Irrigated rice is found from north to south of the Brazil, in subtropical and tropical environments. In the first, rice is concentrated in the states of Rio Grande do Sul and Santa Catarina and is responsible for 80% of national production. In the tropical environment, it is cultivated in the North, Northeast and Central-West and occupies 13,2% of the total cultivated area. Despite being responsible for only 20% of national production, the tropical environment presents important contributions to food security, as pointed out in Embrapa work, then facilitates cereal distribution logistics to states in the North and Northeast from Brazil; minimizes the impacts of severe weather phenomena that can break rice production in southern Brazil; and encourages the establishment of processing industry in production regions.

To the tropical floodplains of the Tocantins-Araguaia river valley have enormous potential for the production of irrigated rice and contribute to Tocantins being the third largest producing state in this category, with 656,6 thousand tons of rice in bark registered in the 2020/2021 harvest, according to data from the National Food Company Supply (Conab).

Through partnerships, Embrapa developed, recently, the cultivar rice BRS A706 CL adapted to tropical regions.

Fortification of partnerships

In recent years, Embrapa has strengthened partnerships with various actors in the rice production chain in Tocantins. One of the main partners are the State University of Tocantins (Unitins), public institution of higher education and responsible for research agriculture in the state. Both institutions coordinate activities at the Center of Várzea Agro-Environmental Research (CPAV), located in the municipality of Formoso do Araguaia, which maintains 145 hectares dedicated to rice experiments irrigated.

Through a technical cooperation contract, the two institutions carry out various research and development activities aiming for an increasingly sustainable production chain. The activities involve trials linked to the Irrigated Rice Improvement Program (MelhorArroz), the development of elite lineages and adequate technical management of the rice. There is even the prospect of launching cultivars, which would the BRSTO name and would be jointly owned.

Other partners who help strengthen the The irrigated rice production chain in Tocantins are seed companies. Since 2019, three private companies have made financial contributions annually within of MelhorArroz, which aims to develop cultivars aimed at specificities of each Brazilian region. Uniggel Sementes, Sementes Simão and Brazeiro Sementes have signed a five-year technical-financial cooperation contract with Embrapa, renewable for the same period, which makes the partnership in Tocantins viable.

Activities include research (from development of elite lines of irrigated rice, undergoing trials regional yields of tropical strains and by value value tests tropical cultivation and use, reaching experimental crops), production of seeds and actions for technology transfer, communication and development of market.