Off-season corn suffers from the dry period

Off-season corn is suffering the effects of the long period of water deficit, from January to May 2021, in the main Brazilian producing states: São Paulo, Paraná and Mato Grosso do Sul. In the producing regions of São Paulo, concentrated in the municipalities of Assis, Pedrinhas Paulista , Votuporanga, Guaíra and Capão Bonito, during this period and in some of these places, it rained 1/3 of what was expected. In Votuporanga, for example, around 640 mm were expected and only 280 mm were recorded in the first five months of this year, according to records from the Agronomic Institute (IAC), of the São Paulo State Department of Agriculture and Supply. This condition impacts supply and prices, causing concern in the market.

According to Angelica Prela Pantano, IAC researcher, crops planted earlier already have a clear compromise in their productive potential, making it possible to observe low vegetative development in the field. "The later ones, which could benefit from the coming rains, expected at the end of May, are also starting to feel it, as the expected rain did not come in sufficient volume to meet the crop's needs in some growing regions", says the researcher .

In São Paulo, most crops were sown from mid-February until the second half of March 2021. At the time of planting, soil moisture was adequate. However, at the beginning of April the rains were scarcer and the water deficiency became even more accentuated in May, when there were many days without rain. In Assis and Pedrinhas Paulista, for example, there was practically no rain in April. "After 60 to 90 days, most crops are in the flowering and grain filling stage, which are critical phases for the development of plants and the definition of productivity", says the researcher at the Agronomic Institute (IAC), Aildson Pereira Duarte .

Some locations in São Paulo had rainfall volumes considered satisfactory in the first months of the year, a situation that changed from March onwards. "The long period of water deficit, which began in February and lasted until May, harms the development of the crop and compromises the productivity of safrinha corn, which may fall in most producing states", says Angélica.

According to Duarte, the situation is serious in the North and Northwest regions of the State, where temperatures are higher, exceeding 30º C, increasing the demand for water by plants. There, there has been no rain since the third decade of March, when 130 to 150 mm of rain were expected. However, in Guaíra, Pindorama and a few other locations, it rained 20 to 30 mm in the period from April 16 to 18, easing the water stress of the plants somewhat.

"In some crops and depending on the hybrid, pollination was compromised due to the lack of pollen to fertilize the receptive anthers of the cob, or "hair" of the corn. Even when there was pollination, the tendency is for the grains at the tip of the cob to remain flat and the others with reduced weight", says Duarte.

In the Middle Vale do Paranapanema region, on the border with Paraná, where the largest area of ​​off-season corn in São Paulo is concentrated, temperatures were milder, on average 22 to 25º C.

According to Aildson and Angelica, the development of the crop is satisfactory only in Alto Paranapanema, Capão Bonito region, for example, where average temperatures prevail, between 18 and 23º C, and more voluminous rains occurred in March. "Thus, in most crops, we observe symptoms of water deficiency from the vegetative stage onwards, such as the loss of turgidity and/or curling of the leaves and the drying out of the lower leaves", explains Duarte.

The rains that occurred in Médio Paranapanema, on the border of the states of São Paulo and Paraná, on May 30th and 31st, alleviated the situation specifically in that region. Total volumes ranged from 50 to 80 mm. But, according to weather forecasting agencies, rainfall should not be heavy in the months of June to August. "This could further worsen the situation of safrinha corn cultivation in the North/Northwest region of the state of São Paulo, compromising part of the 2021 harvest", warns the researcher.

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The Agronomic Institute (IAC) provides technologies that help the crop tolerate drought. Duarte advises that adequate soil management and the use of drought-tolerant cultivars are contributing to reducing productivity losses due to water deficiency. "The difference in the effect of drought between cultivars from similar cycles and between neighboring crops planted at the same time is clear. The good visual appearance of off-season corn stands out in areas with crop rotation and/or a history of cover crops in previous years, reports the researcher.