Irrigation contributes to fruit production during low temperatures

The intense cold has arrived in Rio Grande do Sul and the low temperatures recorded can cause damage to tropical and subtropical fruit species that cannot withstand negative temperatures. One of the methods to prevent the death of plants of these species by freezing is the use of sprinkler or micro-sprinkler irrigation.

In the municipality of Soledade, the young couple of producers Bruna Miranda da Silva and Lucas Muniz invested in pitaya production as a way of diversifying production and, as a result, irrigation became necessary due to the low temperatures frequently recorded in the municipality.

In the 0,4 hectare area where the pitaya plantation is located, the young couple noted the need to invest in automated irrigation to guarantee the cultivation of the fruit due to the occurrence of frequent frosts. In the winter of 2019, the couple made a significant investment in an anti-frost system using microsprinkler irrigation and in equipment for drip irrigation in the pitayas, also sizing the pump to irrigate other crops on the property.

"The low temperatures that Soledade records have always caused us fear. We researched and discovered that it was possible to produce. Last winter we tried to cover the plants, but it didn't work. So, we invested in irrigation and the anti-frost system for this winter. We are curious to see how the plants will behave during the season, as this was the first major frost that hit the plantation this year", comments Bruna, referring to the strong frost in the municipality this Friday (03/07). In addition to pitaya, the couple produces seasonings, cabbage, kale and broccoli, in addition to an area cultivated with pecan trees that have not yet started production.

The agricultural extension agent at Emater/RS-Ascar, Roger Terra de Moraes, explains that pitaya is a tropical species and is not adapted to intense cold. As a result, temperatures below zero cause severe damage and may result in the death of plants or part of them. "With a microsprinkler anti-frost system, the layer of ice that forms on the surface of the plant creates a kind of capsule where the plant's internal temperature does not reach negative temperatures, maintaining the integrity of the plant tissue", he explains.

According to the extension agent, the strategy can also be adopted in fruit trees with a temperate climate in general, cultivated in regions where frost is frequent. "Some species such as peach, plum, vine, among others grown in regions where late frosts frequently occur, this system also proves to be efficient in preserving the integrity of flowering", advises Moraes.

To this end, there are rural credit lines that provide for the financing of the irrigation system, such as the National Program for Strengthening Family Agriculture (Pronaf) with interest of 2,75% per year and a payment period of up to 10 years for family farmers, and the National Support Program for Medium Rural Producers (Pronamp) with interest of 5,0% per year.

Other cultures

Care must also be observed in crops such as vegetables and pastures. In vegetables, cultivation in partially modified environments such as greenhouses and tunnels partially protects the plants from the cold. However, in places where temperatures are excessively low, summer species may die, even those cultivated inside these environments. Another guideline is not to cultivate species that are susceptible to low temperatures or that have their development affected by the cold, such as tomatoes and peppers.

In pasture production, the extension agent guides the cultivation of frost-resistant species, such as oats and ryegrass. "The native pasture stops its growth in these conditions of frost and intense cold, reducing the supply of forage to the animals", highlights Moraes.

In wheat production, which is in the vegetative phase, frosts have little or no negative influence on the crop. "On the contrary, the cold stimulates the tillering of plants, something that is desirable. The lethal temperature for the crop in the vegetative phase is below -9°C, with the rubbering and heading phase being the most sensitive", observes the extension agent.