Classical breeding continues to lead the supply of drought-tolerant sugarcane varieties

An improved sugarcane variety, IACCTC07-8008, launched in 2017 by the Agronomic Institute (IAC), in Campinas, required a strong drought this year to prove its true potential in the field. Planted dryland in a production area, in one of the largest plants in the Goianésia region, in Goiás, it planted an average of 155 tons of sugarcane per hectare compared to 122 tons of other varieties planted in the same soil under identical climatic and ratoon conditions, that is, an average productivity of almost 25% above already established varieties.

“We had high expectations regarding this variety, but the result really surprised us. Researchers in the areas of biotechnology and physiology at the IAC are now trying to understand the reason for this potential for tolerance”, says Marcos Landell, agronomist, researcher and general director of the IAC. According to him, the support from BIOEN – Fapesp's Bioenergy Program was decisive in this research, for example, for setting up the biogenetics laboratory. “Without this, we would certainly not be able to advance at the current speed”, he acknowledges.

Landell says that IACCTC07-8008 is the result of varietal evolution work known as classical breeding. He foresees that different species will be crossed with the expectation that a third variety will combine the best of the previous two. It is a work of persistence, of trial and error, for many years. However, this line of research has proven decisive in obtaining hundreds of varieties that today contribute to increasing productivity levels.

He says that he began fieldwork in Goianésia in the 1990s, a dry region, with weak soil and poorly distributed rainfall throughout the year. “At that time, the average productivity of the first cut was no more than 90 tons. Today, even in conditions of strong water stress, we harvest no less than 120 tons from the sugarcane plant, that is, in the first cycle of the crop. This is the result of a series of factors, but the new varieties contributed a lot to this”, he assesses.

Change in management

In addition to classic improvement, Landell explains that some advances in the area of ​​tolerance to water stress occurred thanks to changes in plantation management. He says that one of these advances developed by the IAC is the so-called Third Axis Matrix. This methodology considers that, with each cycle (cutting) of sugarcane cultivation, the root system develops better, enabling it to reach greater depths. According to the researcher, this information is essential for defining harvest planning, in order to promote the mitigation of water deficit throughout the useful life of a sugarcane field and prevent younger sugarcane from being overly exposed to long periods of drought.

Landell explains that research carried out by the IAC indicated that, contrary to what was believed, the sugarcane root continues to develop and deepen year after year, as long as the plant does not suffer physical-chemical impediments from the soil or the action of any factor, such as pests. . The Third Axis Matrix method defines that the harvesting of sugarcane from the first and second cycles (cuts) must occur by the end of June at the latest, preventing the plant from being exposed to situations of intense water stress when the root is still very superficial. . As a result, sugarcane maintains robust root development and, from the third cycle onwards, it is able to absorb moisture from deeper regions of the soil and continues to deepen year after year, which guarantees better productivity levels in all subsequent harvests.

“This methodology was implemented in the Campo Florido region, in Minas Gerais, by producers who managed to expand productivity from 62 tons of sugarcane per hectare to 116 tons, considering the average of nine cycles (cuts). “This is the result of a well-formed and deep root”, guarantees Landell. According to the general director of IAC, large companies in the sector are already using this methodology with good results. “As producers start to use better varieties, combined with new techniques, we will soon reach the average national sugarcane productivity per hectare above three digits”, he bets.