Knowledge on the ideal conditions for the formation of high quality seedlings is fundamental to guarantee establishment success of crops in a safe and efficient manner. Here, we evaluate the effect of different substrates and irrigation frequencies on the initial growth of parica (Schizolobium parahyba var. amazonicum) seedlings. The experiment was conducted in a greenhouse at the Federal Rural University of Amazônia, Capitão Poço, PA. Several variables were analyzed including seedling height, stem diameter, number of leaflets, shoot dry matter, root dry matter, total dry matter, height and stem diameter ratio, shoot dry matter ratio and root dry matter. We found significant differences in seedling development between the applied treatments, including a significant interaction between substrate type and irrigation regime on seedling height, stem diameter, the number of leaflets and plant growth indices, with the best response for proportions 75% soil + 25% bovine manure and 50% soil + 50% bovine manure. Therefore, the substrates containing organic compounds resulted in a higher quality of the seedlings, while the sand consistently presented the lowest increases in seedling production under the three experimental irrigation frequencies, and thus is not recommended as a substrate for the development of Schizolobium parahyba var. amazonicum.

RESUMO Com o aumento da preocupação com reflorestamento é de grande importância o conhecimento sobre o sistema de produção das espécies florestais nativas com potencial para esse setor. Nesse sentido, objetivou-se avaliar diferentes substratos no crescimento de mudas de guapuruvú. O experimento foi conduzido em casa de vegetação na Universidade Federal Rural da Amazônia, campus de Capitão Poço, durante maio à julho de 2014. O delineamento experimental adotado foi o inteiramente casualizado, constituído de 5 substratos: a) solo local; b) areia lavada; c) 75% de solo + 25% de esterco bovino; d) 50% de solo + 50% esterco bovino e; e) 75% de solo + 25% de esterco caprino, com 4 repetições. As variáveis avaliadas foram altura de planta (AP), número de folíolos (NFOL), massa seca da parte aérea (MSPA), da raiz (MSRA) e massa seca total (MST). Os dados experimentais foram submetidos à analise de variância e as médias foram submetidas ao teste de Tukey, à 5% de probabilidade. Para as variáveis analisadas os substratos 50% solo + 50% esterco bovino e 75% solo + 25% esterco bovino apresentaram as melhores respostas. A areia não é recomendada como substrato. PALAVRAS-CHAVE: agricultura, biomassa, povoamento florestal EFFECT OF SUBSTRATES IN GUAPURUVU SEEDLINGS GROWTH (Schizolobium parahyba (VELL.) S. F. BLAKE) ABSTRACT The increasing concern over reforestation, it´s very important knowledge about the system of production of native species potential for this sector. In this sense, the objective was to evaluate different substrates on growth guapuruvú seedlings. The experiment was conducted in a greenhouse at the Federal Rural University of Amazonia, Capitão Poço campus, during May to July 2014. The experimental design was completely randomized, consisting of 5 substrates: a) local soil; b) washed sand; c) 75% soil + 25% of cattle manure; d) 50% soil + 50% cattle manure and; e) 75% soil + 25% goat manure, with four repetitions. The evaluated variables is plant height

Desertification is a phenomenon that results from the combination of natural factors, mainly the episodic droughts; and anthropogenic factors, such as overgrazing, deforestation and removal of vegetation cover, together with agricultural activities that take place above the carrying capacity of the environment. In Brazil, the Caatinga biome is the most affected, second only to the Atlantic Forest and the Cerrado. It is estimated that 80% of the vegetation is completely modified, due to extractivism and agriculture, with most of these areas in early or intermediate stages of ecological succession. However, the objective of this bibliographical research was to show the causes and consequences of desertification in the Caatinga and the methods that are attributed to prevention. It should be noted that the physical and chemical restrictions of soils, the scarcity of water in the semi-arid Northeast, as well as the intensive exploitation of natural resources and overgrazing make the Caatinga vulnerable to desertification and the threat of extinction of species of fauna and flora native to the region, however, this process can be controlled, avoided, and even reversed, as long as there is the involvement of the population and that government bodies propose solutions, together with communities and schools and the whole society to resolve, or to the less, seek sustainable alternatives, offering technical assistance for the management of these areas and encouraging environmental preservation so that there is no overload of problems in risk areas. In places where the desertification process has already taken place, investments are needed for its containment; however, the cost is in the order of billions of dollars.

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