The use of green manures in vegetable crop production systems has increased, but there is still a lack of information about the correct handling of the species for better use by culture. Two field experiments were conducted in Serra Talhada in the semiarid of Pernambuco state, Brazil, to evaluate the effects of amounts of biomass and times of Calotropis procera incorporation into the soil in the agronomic performance of the beetroot 'Early Wonder' in two growing seasons (fall and spring-summer). The experimental design was a randomized block in three replications. The treatments were arranged in a 4 x 4 factorial scheme, with the first factor corresponding to the quantities of C. procera biomass (5.4, 8.8, 12.2, and 15.6 Mg ha -1 on a dry basis) and the second to the times of incorporation into the soil (0, 10, 20, and 30 days before sowing of beetroot). The following characteristics were assessed in the beetroot: plant height, number of leaves per plant, root diameter, total productivity, commercial productivity, and dry mass of roots. The amount of C. procera as well as the time of incorporation and growing season directly influenced the agronomic performance of beetroot. Regardless of the assessed agronomic characteristics, increasing amounts, and decreasing the time of incorporation proportionally influenced the performance of beetroot. The best agronomic performance of the beetroot was obtained by fertilization with 15.6 Mg ha -1 of C. procera. The ideal time of incorporation of green manure coincided with the date of the sowing of beetroot. The cultivation in the fall season resulted in higher total and commercial productivity of beetroots fertilized with C. procera.

No abstract

Lettuce is a vegetable crop that requires a large supply of nutrients in a readily available form, within a short period of intense vegetative growth. The use of green manuring, with spontaneous species of the Caatinga biome, can quickly increase the organic matter content in the soil, providing nutrients for the crop. Therefore, the objective of this work was to evaluate the agron omic performance and economic profitability of lettuce fertilized with Calotropis procera in single crop under the semi-arid conditions of the state of Rio Grande do Norte, Brazil. The experimental design was a randomized complete block, with four treatments and five replicates. The treatments consisted of four amounts of C. procera biomass incorporated into the soil (10, 25, 40, and 55 t ha-1 of dry matter). The maximum agronomic efficiency of lettuce productivity was obtained for a yield of 18.16 t ha-1 , with 40.29 t ha-1 of C. procera biomass added to the soil. The maximum economic efficiency of lettuce yield was achieved by the net income of AU$3,006.50 (R$7,546.31 ha-1), provided by the production of 17.65 t ha-1 of fresh mass, with 32.20 t ha-1 of C. procera biomass added to the soil. The use of C. procera as a green manure presents agro-economic feasibility for lettuce cultivation in the semi-arid conditions of the Rio Grande do Norte state.

The objective of this work was to evaluate the response of sunflower cultivars submitted to increasing levels of phosphate fertilization in two crops. The experimental design was a randomized complete block design with four replicates in subdivided plots, where five doses of simple superphosphate (0, 50, 100, 150, and 200 kg ha-1 P2O5) were allocated to the plots and three sunflower cultivars (Aguará 06, Altis 99, and Embrapa 122-V2000) were assigned to the subplots. The variables evaluated were the P content in the diagnostic leaf, number of achenes per capitulum, achene yield (kg ha-1), oil content (%) and oil yield. The phosphorus doses increased the components of production. The dose that provided the best sunflower performance varied for the different cultivars. Among the doses studied, fertilization with 100 kg ha-1 P2O5 in the 2016 agricultural crop and 150 kg ha-1 P2O5 in the 2017 agricultural crop provided the best conditions for sunflower cultivation. The cultivar Aguará 06 produced more achenes and oil than the other cultivars analyzed in the agricultural crops.

RESUMO -Planting trees is an important way to promote the recovery of degraded areas in the Caatinga region. Experiments (E1, E2, and E3) were conducted in a randomized blocks design, with three, three, and five replicates, respectively. The objectives were to evaluate biomass of the shoots of: a) gliricidia (G) and sabiá (S), as a response to planting density; b) G, S, and neem (N) in competition; c) G, and S in agroforestry. E1 was conducted in split-plots, and planting densities (400, 600, 800, 1000, and 1200 plants ha -1 ) as subplots. E2 consisted of a factorial comprising the following plots: GGG, NGN, SGS, NNN, GNG, SNS, SSS, GSG, NSN (each letter represents a row of plants). E3 was conducted with G and S in agroforestry experiment. The trees were harvested after 54, 42, and 27 months old, in E1, E2 and E3, respectively. In E1, G presented higher green biomass of the stems and leaf at smaller densities than S, but lower green biomass of branches at most densities. The species did not differ for mean stem dry biomass and leaf dry biomass, but G showed higher branch dry biomass at most densities. Higher planting densities increased green and dry biomass of stems, branches, and leaves in S, but decreased those characteristics in G, with the exception of leaf dry mass, which was not influenced by density. In E2, the behavior of each species was identical in plots containing the same or different species. Griricidia showed the highest green biomass of stems and branches, and the highest values for geren biomass of the leaf were observed for gliricidia and neem. The highest stem, branch, and leaf dry biomass values were obtained for G, S, and N, respectively. In E3, G was superior for stem and leaf green biomass, and for stem and branch dry biomass. There were no differences between species for the other biomass values. Palavras-chave: Azadirachta indica; Gliricidia sepium; Mimosa caesalpiniifolia. BIOMASSAS DE ESPÉCIES ARBÓREAS EM RESPOSTA A DENSIDADES DE PLANTIO E À COMPETIÇÃO INTERESPECÍFICA ABSTRACT -Existe interesse na recuperação de áreas degradadas da Caatinga com o plantio de árvores. Experimentos (E1, E2 e E3) foram realizados, em blocos ao acaso com três, três e cinco repetições, respectivamente, para avaliar as biomassas da parte aérea: a) da gliricidia (G) e sabiá (S), em resposta à densidade de plantio; b) da G, S e nim (N) em competição; e c) da G e S em experimento agroflorestal. E1 foi realizado com

The use of spontaneous species of the Caatinga biome can contribute significantly to the nutritional demand of vegetable crops, thereby providing an agroecological and sustainable form of production. The objective of this research was to determine the effects of different biomasses of Calotropis procera (rooster tree) and times of incorporation into the soil of green manure during two growing seasons on the agronomic performance of coriander cv. Verdão produced in Serra Talhada, a semi-arid region of Pernambuco, Brazil. The experimental design was randomized blocks with three replications. The treatments were arranged in a 4 x 4 factorial scheme, with the first factor consisting of biomass amounts of C. procera (5.4, 8.8, 12.2 and 15.6 t ha -1 on a dry basis) and the second by the incorporation times into the soil (0, 10, 20 and 30 days before coriander planting). The evaluated characteristics were plant height, number of stems per plant, yield of green mass and dry mass of shoot. The best productive performance of coriander was observed in amounts of 12.2 (spring) and 8.8 (autumn-winter) t ha -1 C. procera added to the soil, with an ideal incorporation time of 13 (spring) and 23 (autumn-winter) days before sowing of the crop and with larger accumulations of green and dry mass of the shoot being obtained in autumn-winter.Index terms: Coriandrum sativum L.; organic cultivation; rooster tree. RESUMOO uso de espécies espontâneas do bioma Caatinga pode contribuir de forma significativa no suprimento nutricional demandado pelas hortaliças, sendo uma forma agroecológica e sustentável de produção. O objetivo da pesquisa foi determinar os efeitos de quantidades de biomassa de Calotropis procera (flor-de-seda), de tempos de incorporação ao solo do adubo verde e de duas épocas de cultivo sobre o desempenho agronômico do coentro cv. Verdão produzido em Serra Talhada, semiárido de Pernambuco, Brasil. O delineamento experimental foi em blocos casualizados, com três repetições. Os tratamentos foram arranjados em esquema fatorial 4 x 4, com o primeiro fator constituído por quantidades de biomassa de C. procera (5,4; 8,8; 12,2 e 15,6 t ha -1 em base seca), e o segundo pelos tempos de incorporação ao solo (0, 10, 20 e 30 dias antes do plantio do coentro). As características avaliadas foram altura de plantas, número de hastes por planta, rendimento de massa verde e massa seca da parte aérea. O melhor desempenho produtivo do coentro foi observado nas quantidades 12,2 (primavera) e 8,8 (outono-inverno) t ha -1 de C. procera adicionada ao solo, com um tempo ideal de incorporação de 13 (primavera) e 23 (outono-inverno) dias antes da semeadura da cultura e com maiores acúmulos de massas verde e seca da parte aérea sendo obtidos no outono-inverno.Termos para indexação: Coriandrum sativum L.; cultivo orgânico; flor-de-seda.

Sunflower is an oleaginous plant of great importance worldwide that stands out in the production of edible oil and human food. The identification of differences between cultivars regarding the use of phosphorus and the production of achenes at different levels of phosphate fertilization is a viable strategy to allow its cultivation in soils with different concentrations of phosphorus, without compromising yield and reducing environmental damage associated with excessive applications of phosphate fertilizers. Thus, the objective of this study was to evaluate different levels of phosphorus fertilization and sunflower cultivars regarding the efficiency of phosphorus use in two agricultural crops. The experimental design was in randomized blocks with four replications in split-plots, where four doses of phosphorus (50, 100, 150, and 200 kg ha−1 of P2O5) were allocated in the plots, and in the subplots three sunflower cultivars (Aguará 06, Altis 99, and BRS 122). The phosphorus use efficiency of sunflower cultivars was estimated through agronomic efficiency, vegetative efficiency, agrophysiological efficiency, apparent recovery efficiency, and utilization efficiency. The dose of 50 kg ha−1 of P2O5 provided the best phosphorus efficiency indices for the different sunflower cultivars in the two studied crops. Cultivar Aguará 06 was more efficient in conditions with P2O5 supply below 150 kg ha−1, regardless of the crop. Sunflower cultivars had the best efficiency indices of phosphorus applied in the 2016 harvest.