RESUMO Diversas ações humanas têm causado degradação de solos e a revegetação dessas áreas é uma alternativa de recuperação. Contudo, em solos afetados por sais, é fundamental escolher espécies adequadas para a extração de sais do solo. Neste estudo o objetivo foi avaliar o desenvolvimento e a resposta de espécies arbóreo-arbustivas cultivadas em solo degradado por sais, estabelecidas isoladamente ou associadas à espécie fitoextratora de sais, por meio da produção de biomassa e extração de elementos pelas plantas. Um experimento de campo foi instalado em Serra Talhada-PE com oito tratamentos: 1) Atriplex nummularia Lindl., 2) Mimosa caesalpiniifolia Benth, 3) Leucaena leucocephala (Lam.) de Wit, 4) Azadirachta indica A. Juss, 5) A. nummularia + M. caesalpiniifolia, 6) A. nummularia + L. leucocephala e 7) A. nummularia + A. indica; em blocos casualizados com quatro repetições. Após 30 meses de cultivo, as plantas foram coletadas e pesadas, analisando-se teores de Na, K, Ca, Mg, Cl, P e N. Plantas de A. indica produziram mais biomassa total (10,75 kg planta-1), cerca de 15 vezes mais que M. caesalpiniifolia, ambas em cultivo associado com A. nummularia. Plantas de A. nummularia extraíram mais Na e Cl na matéria seca, com máximo de 124,70 e 166,79 g planta-1, respectivamente. A mais alta produção de biomassa vegetal (23,55 t ha-1) e extração total de elementos (1438,51 kg ha-1) foi no cultivo associado de A. nummularia e A. indica. O cultivo associado não diminuiu o potencial fitoextrator de A. nummularia, e pode ser utilizado em áreas sob recuperação.

ABSTRACT Anthropogenic actions have caused soil degradation and revegetation is a way to recover degraded soils. However, salt-affected soils require the use of suitable species to extract salts from the soil. This study investigated the growth of shrub and tree species in a soil degraded by salts, alone or associated with a phytoextraction salt species, evaluating plant biomass yield and extraction of elements by plants. A field experiment was assembled with eight treatments: 1) Atriplex nummularia Lindl., 2) Mimosa caesalpiniifolia Benth, 3) Leucaena leucocephala (Lam.) Wit, 4) Azadirachta indica A. Juss, 5) A. nummularia + M. caesalpiniifolia, 6) A. nummularia + L. leucocephala and 7) A. nummularia + A. indica; in randomized blocks with four replications. After 30 months of cultivation, plants were collected to measure biomass and concentrations of Na, K, Ca, Mg, Cl, P, and N. A. indica plants had the highest total biomass (10.75 kg plant-1), about 15 times more than M. caesalpiniifolia, both in associated cultivation with A. nummularia. A. nummularia plants extracted more Na and Cl in the dry matter, maximum of 124.70 and 166.79 g plant-1, respectively. The highest production of plant biomass (23.55 t ha-1) and total extraction of elements (1438.51 kg ha-1) were obtained by associated cultivation of A. nummularia and A. indica. Associated cultivation did not decrease the phytoextractor potential of Na and Cl by A. nummularia plants and it can be used to regenerate degraded areas.

RESUMO Sistemas consorciados de beterraba x caupi-hortaliças estão começando a ser implantados no semiárido nordestino. O grande desafio é saber se existe ou não eficiência agroeconômica nesses sistemas quando adubados com matéria orgânica produzida por espécies espontâneas do bioma Caatinga. Assim, o objetivo desta pesquisa foi avaliar o efeito da adubação verde utilizando diferentes quantidades de jitirana (Merremia aegyptia) na associação de beterraba com caupi-hortaliça nas condições do semiárido. O experimento foi realizado na Fazenda Experimental Rafael Fernandes, zona rural de Mossoró, RN, no período de setembro-dezembro de 2015, em delineamento experimental de blocos casualizados com quatro tratamentos e cinco repetições. Os tratamentos consistiram de quantidades de jitirana incorporadas ao solo (10, 25, 40, 55 t ha-1 em base seca). As cultivares de beterraba e do caupi-hortaliça plantadas foram ‘Early Wonder’ e ‘BRS Itaim’, recomendadas para as condições semiáridas do Nordeste brasileiro. O melhor desempenho agroeconômico para o consórcio de beterraba e caupi-hortaliça foi obtido com 55 t ha-1 de jitirana incorporada ao solo. O uso da espécie jitirana como adubo verde é agronomicamente viável em sistemas consorciados de beterraba com caupi-hortaliça.

ABSTRACT Intercropping systems of beet and green cowpea are beginning to be implemented in the northeastern semi-arid region in Brazil. The great challenge is to know if there is agro-economic efficiency in these systems when fertilized with organic matter produced by spontaneous species of the Caatinga biome. Thus, the objective of this research was to evaluate the effect of green manuring using different amounts of hairy woodrose (Merremia aegyptia) in the association of beet with green cowpea under the semi-arid conditions. The experiment was carried out at the Rafael Fernandes Experimental Farm, rural area of Mossoró, RN, Brazil, in the period of September-December 2015, in a randomized complete block design with four treatments and five replicates. The treatments consisted of hairy woodrose amounts incorporated into the soil (10, 25, 40, 55 t ha-1 on a dry basis). The cultivars of beet and green cowpea planted were ‘Early Wonder’ and ‘BRS Itaim’, recommended for the semi-arid conditions of the Brazilian Northeast. The best agro-economic performance for intercropping system of beet and green cowpea was obtained with 55 t ha-1 of hairy woodrose incorporated in the soil. The use of the hairy woodrose species as green manure is agronomically viable in intercropped systems with beet and green cowpea.

ABSTRACT Inga edulis Mart. is a leguminous tree adapted to acidic and low-fertility soils that establishes symbioses with nitrogen (N)-fixing bacteria. The identification of effective bacteria in biological N fixation may bolster the use of I. edulis in degraded or modified areas and agroforestry systems. Therefore, the aims of this study were evaluation of the symbiotic effectiveness of eight strains of the Bradyrhizobium genus native to Roraima in Inga edulis plants, and in vitro evaluation of the ability of the eight strains of Bradyrhizobium to develop plant growth-promoting characteristics. Determination of symbiotic effectiveness was carried out via three experiments: the first in a greenhouse in pots with a sterile substrate; the second in a greenhouse in pots containing non-sterile soil; and the third in a nursery in bags with a non-sterile substrate. Twelve treatments were evaluated: inoculation with eight strains of Bradyrhizobium ingae (ERR 490, ERR 492, ERR 493, ERR 494T, ERR 496, ERR 497, ERR 498, and ERR 569); inoculation with two strains indicated for Inga marginata, BR 6609 and BR 6610 (positive controls); no inoculation but with mineral N; and neither inoculation nor mineral N. All of the experiments were conducted in a completely randomized design with four replicates. The first experiment was conducted for 60 days, and the other experiments were conducted for 100 days. For all of the experiments, the number of nodules, nodule dry matter, root dry matter, shoot dry matter, number of leaflets, plant height, stem diameter, total N in the shoots, root/shoot dry matter ratio, Dickson’s quality index, relative effectiveness, and the Pearson correlation between the variables under study were evaluated. The strains were also evaluated by their ability to solubilize calcium and aluminum phosphates and to produce indolic compounds. The results showed that B. ingae strains were effective in biological N fixation, especially the ERR 493, ERR 498, and ERR 569 strains. These strains increased the production of shoot dry matter and total N and exhibited relative effectiveness higher than 100 % in all of the experiments. The B. ingae strains were also able to solubilize calcium and aluminum phosphates, despite their synthesis of indolic compounds. Thus, the strains of B. ingae can be used for inoculation in the production of I. edulis seedlings.