Rômulo Magno Oliveira de Freitas

Produção e qualidade de sementes de feijão-caupi em função de sistemas de plantio e estresse hídrico

The cowpea plays an important role in the Brazilian agricultural production, especially in the North and Northeast Regions, where it is widely cultivated by smallholders. Thus, this study aimed at evaluating the physiological quality of cowpea seeds produced under no-tillage and conventional tillage and different periods without irrigation. A randomized blocks design, in a split-plot scheme, with four replications, was used. The plots consisted of cropping systems (no-tillage and conventional tillage), while the subplots consisted of periods without irrigation (2, 6, 10, 14, 18 and 22 days). In the plots, seeds were collected and subjected to the following evaluations: seeds weight per plant, one thousand seeds weight, test weight, seed length and width, moisture content, germination, accelerated aging, field seedling emergence and emergence speed index. Cowpea seeds from plants subjected to hydric stress resulted in lower physiological quality, but were physically bigger and heavier. The no-tillage system provided seeds with better physiological quality. Cowpea plants subjected to hydric stress after flowering produced fewer seeds.

Temperaturas e substratos na germinação de sementes de pereiro-vermelho (Simira gardneriana M.R. Barbosa & Peixoto)

O pereiro-vermelho e uma especie florestal pertencente a familia Rubiaceae, considerada endemica do bioma Caatinga. O presente trabalho teve como objetivo definir o tipo de substrato e a temperatura mais adequados para a germinacao de sementes de pereiro-vermelho (Simira gardneriana M.R. Barbosa & Peixoto). Dessa forma, realizou-se experimento em delineamento inteiramente ao acaso e arranjo fatorial 5 x 4, constituidos pelas combinacoes de cinco substratos (entre areia, sobre areia, rolo de papel, sobre papel e sobre vermiculita) e quatro temperaturas (constantes de 25; 30; 35 °C e alternada de 20-30 °C), com quatro repeticoes de 25 sementes cada. Foram analisadas as seguintes variaveis: porcentagem de germinacao, porcentagem de plântulas anormais, indice de velocidade de germinacao, comprimento e massa seca das plântulas. As temperaturas de 25 e 30 °C e os substratos rolo de papel ou areia sao condicoes ideias para a germinacao das sementes de pereiro-vermelho.

Efeito da salinidade na emergência e crescimento inicial de plântulas de flamboyant

The objective of this study was to evaluate the effect of different salt concentrations in irrigation water on the emergence and initial development of flamboyant (Delonix regia (Bojer ex Hook.) Raf.) seedlings. The experiment was conducted in the greenhouse of the Department of Plant Sciences, Universidade Federal Rural do Semiarido - UFERSA, Mossoro-RN. The statistical design was completely randomized with five treatments and four replicates, each with 25 seeds. The treatments consisted of salt concentrations (0.5, 1.5, 3.0, 4.5 and 6.0 dS m-1), obtained by adding NaCl to water so that the solutions were calibrated to the pre-established electrical conductivity values. The variables measured were: percentage of seedling emergence, rate of emergence, leaf area, seedling height, number of leaves, root length and shoot dry weight. Salinity negatively affects all variables directly proportional to its increase in the irrigation water, with the greatest seedling development at a dose of 0.5 dS m-1.

Gibberellic acid enhances the emergence of Zizyphus joazeiro seeds.

Zizyphus joazeiro (Rhamnaceae) is a native species of the Brazilian semiarid region. It has a very low germination rate, thus complicating the scion production for reforestation projects and commercial use. Several species from Rhamnaceae have been reported to increase germination when treated with gibberellic acid (GA3). The purpose of this work was to study the effect of gibberellic acid on the rate and speed of emergence in this species. Three GA3 solutions (1, 2, and 3 mM), along with a control of distilled water, were evaluated using seeds previously treated with sulfuric acid. The GA3 treatments enhanced the emergence of seeds. Sixty-two days after sowing the GA3 treatment-induced seeds, percentage emergence increased almost five times in comparison with nontreated seeds. However, there was no statistical difference among the three concentrations of GA3. Thus, Zizyphus joazeiro seed treatment with GA3 is simple and adequate for scion production.

Crescimento de cultivares de Ipomoea batatas oriundas de rebentos produzidas de forma convencional e in vitro

This work had the objective of analyzing the growth and agronomic behavior of sweet potato cultivars originated from conventionally or in vitro produced sprouts. The experimental design was a 5×2 full factorial in randomized complete blocks with four replicates. The treatments were five sweet potato cultivars (‘ESAM 1’, ‘ESAM 2’, ‘ESAM 3’, ‘Branca do Rio de Janeiro’ e ‘Califórnia’) and two propagation methods (conventional and in vitro). For the growth analysis, plant were collected at 40, 60, 80, 100 and 120 days after planting, from which was measured the plant dry mass, the tuberous root dry mass, and the leaf area. The following physiological indexes were calculated: absolute and relative growth rates, leaf area index and net assimilatory rate. A significant interaction among cultivars, propagation forms and evaluation time for all variables was observed. The highest values were obtained for the plants originated from in vitro culture. Cultivar ‘ESAM 2’ exhibited a higher plant dry mass, absolute growth rate and tuberous roots dry mass.

The use of saline aquaculture effluent for production of Enterolobium contortisiliquum seedlings

The use of aquaculture effluent for irrigation of field crops has been suggested as the most appropriate biological method for treatment of this effluent. However, using it for irrigation of tree species in seedling nurseries might be a better alternative to avoid soil salinization and groundwater contamination in agricultural fields. This paper aimed at assessing the production of Enterolobium contortisiliquum seedlings under irrigation with saline aquaculture effluent. The experiment was carried out in a randomized complete block design with four replicates and four seedlings per experimental unit. Each replicate was daily irrigated with five solutions containing different concentrations of saline aquaculture effluent diluted with freshwater (0, 25, 50, 75 and 100% effluent). Despite increasing substrate salinity, the dilution of saline aquaculture effluent in the irrigation water promoted greater shoot growth and higher total dry weight in E. contortisiliquum. Moreover, seedlings treated with low concentrations of this effluent increased their leaf area expansion and chlorophyll content. Therefore, the use of solutions containing 25 and 50% effluent allowed the production of high-quality seedlings. These results suggest that saline aquaculture effluent can be reused to irrigate tree species, enabling a successful integration of aquaculture and agriculture and reducing environmental impacts of improper effluent disposal.

PRODUÇÃO DE MUDAS DE Enterolobium contortisiliquum E PARTIÇÃO DE ASSIMILADOS EM RESPOSTA À ADUBAÇÃO FOSFATADA E INOCULAÇÃO COM FUNGOS MICORRÍZICOS

This study aimed to evaluate the production of Enterolobium contortisiliquum (Vell.) Morong seedlings and assimilate partitioning under different levels of phosphorus, in the presence and absence of arbuscular mycorrhizal fungi. The experiment was conducted in randomized blocks in a 5x2 factorial design, with four replications represented by three plants each. The first factor consisted of P levels (0, 50, 100, 150 and 200 mg.Kg soil -1 ), using superphosphate fertilizer (P 2 O 5 ) as the phosphorus source. The second factor consisted of the presence or absence of arbuscular mycorrhizal fungi. At 98 days after sowing (DAS), plants were evaluated by non-destructive assessments of shoot height (APA), leaf number (NF) and stem diameter (DC). Then, chlorophyll content index (ICC), leaf dry matter (MSF), stem dry matter (MSC), shoot dry matter (MSPA) and root dry matter (MSR) analyses were conducted. Leaf area (AF), leaf weight ratio (RPF), specific leaf area (AFE), Dickson quality index (IQD) and shoot/root dry matter ratio (MSPA/R) were also determined. The P level of 100 mg.Kg -1 proved to be the most efficient one for the production of Enterolobium contortisiliquum seedlings in Mossoro, Rio Grande do Norte state, with no benefits in the use of mycorrhizal fungi until 98 DAS, promoting photoassimilate distribution between the organs of young seedlings favorable to the establishment in the field.

CRESCIMENTO DE Mimosa caesalpiniifolia Benth., SOB SOMBREAMENTO NO SEMIÁRIDO NORDESTINO

Seedling production for reforestation aims to achieve the best plant growth in a minimal amount of time, to provide good survival and growth levels after transplantation. During cultivation, it is necessary to know the shading levels that lead to the best growth. The objective of this study was to assess the growth of young Mimosa caesalpiniifolia Benth. plants provided with various amounts of shade in the northeast semi-arid region of Brazil. Four types of shade cloth were tested (0, 30, 50 and 70%). Shoot length, stem diameter, stem dry matter, leaf dry matter, total dry matter and leaf area were assessed. Leaf area ratio, specific leaf area, absolute growth rate, relative growth rate and net assimilation rate were also calculated. The different shading levels affected M. caesalpinifolia growth, with the best growth indicators observed in plants grown under 50% shade, with increases in plant height, leaf area and total dry matter observed compared to the full sun condition.

Teste de tetrazólio para avaliação da qualidade fisiológica de sementes de Vigna unguiculata (L.) Walp.

RESUMO - O objetivo do trabalho foi desenvolver procedimentos apropriados para a conducao do teste de tetrazolio com o intuito de verificar a viabilidade de sementes de feijao-caupi. Foram avaliadas duas temperaturas, 35 e 40 °C; tres concentracoes de tetrazolio, 0,05; 0,075 e 0,1%; por tres tempos, 90; 150 e 210 minutos. Paralelamente, foram conduzidos testes de germinacao e emergencia de plântulas, condutividade eletrica e envelhecimento acelerado, estabelecendo-se criterios para avaliacao da viabilidade e vigor. As sementes foram tipificadas em dois grupos, viaveis e inviaveis, as quais apresentaram adequada relacao com a emergencia. A avaliacao da viabilidade e vigor das sementes de feijao-caupi, por meio do teste de tetrazolio, e eficiente com o emprego do pre-condicionamento de imersao direta em agua por 16 horas, a 25 °C, e utilizacao da solucao de tetrazolio na concentracao de 0,05%, por 210 minutos, na temperatura de 40 °C. Palavras-chave: Feijao-caupi. Germinacao. Vigor.

Desempenho agronômico de cultivares de batata-doce oriundas de ramas produzidas de forma convencional e in vitro - DOI:10.5039/agraria.v8i3a2353

Este trabalho teve como objetivo avaliar o desempenho agronomico de cultivares de batata-doce [ Ipomoea batatas L. (Lam.)] oriundas de ramas produzidas de forma convencional e in vitro, nas condicoes edafoclimaticas de Mossoro-RN. O delineamento experimental utilizado foi o de blocos ao acaso, em esquema fatorial 5 x 2, com quatro repeticoes. Os tratamentos consistiram da combinacao de cinco cultivares de batata-doce (ESAM 1, ESAM 2, ESAM 3, Branca do Rio de Janeiro e California) e duas formas de propagacao (convencional e in vitro). As caracteristicas avaliadas foram: Produtividades total, comercial e nao-comercial de raizes; massa de raizes comerciais; numero de raizes comerciais e total por planta; massa seca da parte aerea, de raizes e total. A propagacao in vitro proporcionou, em todas as cultivares de batata-doce maior numero e produtividade de raizes comerciais, sendo a cultivar ESAM 1 a que apresentou os maiores ganhos percentuais. As cultivares California e ESAM 2 foram as mais produtivas, respectivamente na propagacao convencional e in vitro.