Baru has not been domesticated yet, and its advance may lead to a production system for this nut, which is originally from the Cerrado biome. One of the main challenges to domesticate baru trees is the production of seedlings from materials with superior traits, the focus of this study. Multiplication by vegetative propagation allows uniformity and high yield. Besides the seed, which is the most popular part, the fruit also has edible pulp and an endocarp that can be transformed into coal. Grafting is a good technique to reproduce Cerrado native species. Grafting, a method of vegetative propagation to produce clones, has been proven viable to multiply baru trees. Recent studies conducted at the plant nursery at Embrapa Cerrados presented promising results for three types of grafting: budding, cleft grafting, and splice grafting (see the box at the end of the news article). For the seedlings grown in full sun, the three types provide a fixing average of over 50%, especially budding, which reached over 60%. Vegetative propagation Vegetative propagation or cloning consists on the multiplication of plant parts of interest without the use of seeds, which has other plants that are identical to their mother plant (clones) grow. The main advantages of the method include the possibility of establishing highly productive and highly uniform plantations and, sometimes, anticipating the reproductive stage of the species. In addition to grafting, other methods of asexual reproduction or vegetative propagation are cutting, mini-cutting, and micropropagation. These are the first results of the development of a production system of baru trees. “We highlight we are dealing with a native tree species lacking of technical information on it, and we believe these data will base new studies aimed at improving the grafting methodology of the species”, the researcher Wanderlei Lima emphasizes. He is the coordinator of the study. The full findings are in the paper “Avaliação de métodos de enxertia em mudas de baruzeiro (Dipteryx alata Vogel, Fabaceae)”, published in the journal Ciência Florestal, in the April/June 2023 issue. Lima explains that the next step is to refine the process using the acquired experience in the first experiment and increase the percentage of seedling fixation. The result was very positive according to the team, which is also composed of the analyst Fernanda Morais and the assistant Vicente Moreira. Some of the grafted seedlings at Embrapa Cerrados have already been transplanted to a field in the border of an integrated crop-livestock-forestry system (ICLFS) experiment, in which the use of Cerrado native species is being evaluated (read news article). One of the main challenges to domesticate baru trees is the production of seedlings. Currently, there is no validated asexual reproduction methodology for the species. Baru tree (Dipteryx alata Vogel) Also called cumbaru or cumaru in Brazilian Portuguese, baru trees are 15 to 25 meters tall and are widely distributed in the Cerrado biome. This is one of the native species of the biome with great economic potential due to its diverse uses. The fruit pulp can be consumed fresh or in mixes, and its endocarp can be transformed into coal with high calorific value. Its seed is the most popular part and has gained market value, as it is used in national and international cuisine. It resembles a nut and can be appreciated as an appetizer or used in several recipes. The oil extracted from the seed has several uses as well. The tree can be used in landscaping and its wood has great resistance and durability. Baru trees are one of the most promising species for cultivation; thus, the generation of information on its multiplication, growth, development, yield, and variability will allow its domestication for commercial cultivation. At the moment, practically all baru production comes from forest extraction activities. Photo: Alexandre Veloso The experiment Three kinds of grafting were tested (budding, cleft grafting, and splice grafting) in three systems to conduct rootstocks (plastic bags in full sun, under shade, and tubes in a suspended nursery in full sun). The seedlings (rootstocks) were formed from seeds collected from mature baru trees in the experimental field at Embrapa Cerrados. The buds used for grafting were also obtained from adult trees at Embrapa How is grafting done? Many fruit trees are multiplied through grafting. It not only keeps the desirable characteristics in the resulting plant, but is also a fast and reliable way to reproduce superior plants for commercial cultivation. The technique involves the introduction of a bud, a plant sprout, or a branch, into another plant that is called rootstock. The grafted plant carries the characteristics one wants to obtain onto the new plant, and it will be the one to bear fruit. The rootstock is formed by the root system and part of the stem; it is responsible for providing water and nutrients to the plant and for ensuring its adaptation to soil and climate conditions. The performance of the plants was different according to each conduction system. “We considered the seedling production system in plastic bags in full sun the best one. We achieved over 50% fixing in the three types of grafting we used in our study, in which budding was the most effective, followed by cleft grafting and splice grafting”, Lima informs. According to the researcher, only splice grafting had a fixing percentage above 50% for seedlings conducted in the shade, which indicates that it is a technique to reproduce the species in such conditions. However, the time spent for the seedlings to reach the ideal diameter for grafting was higher in the systems under shade. Considering the seedlings were formed on the same day, the seedlings under shade only reached the ideal diameter three months later than the seedlings conducted in full sun. This is important information both for the multiplication and the domestication of the crop, since the higher the time the seedling takes to reach the ideal diameter for grafting, the higher the costs during this stage. About the third conduction system, Lima clarifies: “We decided not to use grafting in tubes or suspended nursery in the study, because these methods present the worst performance in growing and development”. The researcher considers this a very positive result: “As it is the first experiment, the figures were very satisfying. We aim to reach 80% by refining the technique and verifying some factors that could have affected the seedlings development”. Lima observes that the experiment was carried out during the most critical period of the covid-19 pandemic, when many studies were compromised. Based on the findings from the experiment, the recommendation for those who wish to produce baru seedlings is to redo the grafting of the seedlings that do not take. “This ensures reduced production costs since it reuses the rootstocks”, he comments. Photo: Wanderlei Lima Types of grafting evaluated in the experiment In grafting, part of a plant whose characteristics are desirable is “implanted” in the stem of another plant, fusing those two parts. Budding – A bud of the plant to be multiplied is introduced in a cut done in a seedling that will be the rootstock. Apical grafting – Two parts of a plant with the same diameter are perfectly placed into each other. A rope is used to tie them together. There are two types of apical grafting: cleft grafting and splice grafting. They differ due to the cut done to the plants to fit them in. The first one entails a v cut, and the second, a transversal cut. Photo: Wanderlei Lima Promising results Vegetative propagation or cloning is an excellent tool for forestry production in Brazil, providing an increasing yield of planted forests with non-native species. However, its use with native plant species is still incipient. The few baru-tree orchards are formed by seedlings originated from seeds. “Sexual reproduction [using seeds] involves high genetic variability, so it does not guarantee the offspring will have the same characteristics of the mother. On the other hand, asexual reproduction [vegetative propagation], with clone production, assures these characteristics will be maintained. This is an important tool to multiply different materials of interest”, Lima explains. Previous studies carried out in 2002 and 2003 at Embrapa Cerrados evaluated other methods of vegetative propagation for baru trees. The cutting method, despite being a very popular technique to forest species, did not show good results, since the baru tree presents difficult rooting. The buds sprouted, but the roots did not grow. Simultaneously to the current experiment, epicormic growth was stimulated with severe pruning of mature plants, in order to new buds to arise. According to the researcher’s evaluation, the species resprouts easily, and the use of these buds represent a potential source for asexual reproduction that has not been explored yet. Grafting has two purposes: helping the breeding and genetic improvement of the species and enabling the multiplication of superior plants. “Grafting may be the first step to domesticate native species of the biome, especially those that are difficult to be reproduced through cutting. Then, it will be possible to select elite materials with desirable characteristics, such as shorter trees to facilitate the management, more homogeneous orchards, and trees with higher yield potential”, the researcher informs. Another advantage of using the technique is reducing the time to start the production. The scientist informs that, in the last decades, the demand for products of Cerrado native species has increased. Despite this reality, a large portion of the production comes from forest extraction. Baru stands out among native fruit trees due to its high economic potential, which can be used to restore degraded lands, recover legal reserves, and establish commercial orchards. “Its domestication may open a very profitable market to local farmers”, he concludes. Photo: Alexandre Veloso Edited on Jul 04 18:30 to reflect the latest version of the original in Portuguese.