Fusariosis-resistant grafting revives passion fruit production in Mato Grosso

Ongoing research in the municipality of Terra Nova do Norte (MT) is bringing hope to passion fruit producers in Mato Grosso and reactivating the culture in the state. The work, carried out in partnership between Embrapa and the Coopernova cooperative, validates the resistance to fusariosis of grafted passion fruit plants. Caused by fungus Fusarium oxysporum f. passiflorae, the disease affects the roots and kills the plants within a few days, making cultivation in infected areas unfeasible.

Preliminary data show that at least one of the three rootstocks used has proven resistant to the disease in the climatic and soil conditions of that region. While the plants grown without grafting (straightfoot) died and some of those grafted onto Alata passionflower e Passiflora gibertii have also presented the problem, all plants grafted into Passiflora nitida they remain alive, without symptoms and producing well.

The result is a relief for producers, since fusariosis practically made passion fruit cultivation in the Terra Nova do Norte region unviable. Between 2008 and 2009, more than 300 members produced passion fruit. The production was sold fresh or processed in the cooperative's agribusiness. In two years, around 90% of producers abandoned their activity due to problems with the disease. The loss of investment was added to an idle capacity of around 85% of Coopernova's processing industry.

Adversity leads to solution

The problem was so big in the region that, from it, the solution emerged. Firstly, producers and the cooperative's technical team observed that in the same areas where the sour passion fruit plants died, there were species of wild passion fruit that remained alive. Intrigued, they began researching ways to use that resistance in sour passion fruit plants.

The solution was found in a passion fruit grafting technique developed around 15 years ago. Responsible for innovation, the researcher at Embrapa Agrosilvopastoral Givanildo Roncatto explains that, unlike other species such as mango and citrus, for example, grafting in passion fruit does not depend on removing branches from adult plants.

"In the nursery phase, 100% young seedlings are used. You produce everything by seed, not only the rootstock, but also the plant that will give rise to the scion. Young plants do not have a hollow stem, like adults. Hollow stems are a problem, as the grafted plant does not grow,” explains Roncatto.

Coopernova's technical director, Carlos Távora, was the one who started collecting and multiplying the seeds of wild passion fruit, which later came to be identified as Passiflora nitida. He used the seedlings as rootstock and, since then, with support from Embrapa, he has been carrying out tests in the nursery and in the field. The good results led to a return of interest from farmers.

Currently, around 90 farmers have returned to passion fruit cultivation. All of them using grafted seedlings produced in the Coopernova nursery. According to Távora, demand from cooperative members reaches 40 thousand seedlings per year, three times greater than production capacity.

“If we are able to meet the demands of producers, not only in the region, but also in the state, the tendency is for a progressive increase not only in the area, but also in passion fruit productivity in the state. Fusarium wilt has been a limitation as it causes high plant mortality. As in grafting we practically eliminated this mortality, the trend is towards an increase”, predicts Carlos Távora.

One of the producers who abandoned passion fruit production after the death of four hectares of crops was Odair Piccini. Today, thanks to the grafted seedlings, it has returned to activity and already has eight hectares planted.

“The seedlings are very satisfactory. It's easy to move. It increased productivity by 25% or more, and is even better for disease control. As it provides less foliage, it makes it easier to combat mites and cochineal”, says the producer, who has plans to expand passion fruit planting to 15 hectares and offers his site for research development.

Productivity increase

The research conducted by Embrapa in Terra Nova do Norte is still ongoing and will only have final data on productivity after the end of the two-year cycle. However, evaluations carried out by the Coopernova team demonstrate that grafted feet are more productive than straight feet.

In areas with three years of production, it was observed that in the first year the trees produced more. In the second year there is a balance and in the third the grafted plants produce more. The greater longevity of the plants is another aspect still being evaluated, but the cooperative team is already extending the crop cycle from two to three years.

Another concern of researchers is the possibility of incompatibility between the scion and the rootstock, causing damage to the scion.

“An incompatibility leads to a difference in stem diameter. Then there may be plant death, or less growth. In the experiment, we are verifying that there is some incompatibility with the rootstock, mainly P. gibertii. But it is believed that this will even be beneficial, as the vegetative part develops less and the plant produces more. A balance occurs. Less vegetative growth and greater fruit production”, assesses Roncatto.

Fruit quality

To ensure the feasibility of using rootstocks resistant to fusariosis, fruit quality indicators were also evaluated. Physical and chemical aspects were tested. According to the Embrapa researcher Sílvia Campos, no differences were found in relation to the fruits of francaises.

“What we have to keep in mind post-harvest is whether the fruits are suitable for the market, whether there is no loss in the quality of the fruits, regardless of the types of rootstock. We were able to observe that there is no difference, despite the amount of soluble solids (amount of sugar) in the grafted fruits being higher than that in fruits harvested from free trees”, explains Sílvia Campos.

To date, research has only worked with the cultivar BRS Rubi do Cerrado at the Worldcup. The next step will be to test other cultivars and all evaluations will be redone.

“It is important that the characteristics of the cultivars used in the scion are maintained, even with the use of the rootstock. If we have a bad response, it is likely that that combination of cultivar and rootstock is not suitable for a given region”, says the researcher.