GROWTH, YIELD AND POST-HARVEST EVALUATION OF LETTUCE PLANTS SUBJECTED TO DIFFERENT LEAF SILICON CONCENTRATIONS

Lettuce is considered the most produced and consumed leafy vegetable; however, it has short post-harvest life, which generates significant losses for both producers and consumers. Studies have proven the beneficial effect of silicon on fruits and vegetables. Therefore, the aim of the current study is to evaluate the influence of leaf calcium silicate application on the growth, biomass production and postharvest conservation of curly lettuce. The experiment was carried out in greenhouse at Federal Rural University of Amazonia, Parauapebas Campus / PA. It followed a completely randomized design (CRD) with five Si concentrations (0.0, 2.0, 4.0, 6.0 and 8.0 mg L-1) and eight repetitions, which totaled 40 plants. Plants were grown in plastic pots (capacity = 3 dm3) filled with soil classified as Red-Yellow Argisol. Different Si concentrations were applied to plant leaves, at the 20th and 27th days after transplantation (DAT). Silicon has favored the growth and development of lettuce plants, as well as reduced their post-harvest weight loss. It was possible concluding that the herein tested Si concentrations, which were applied to leaves - in the form of calcium silicate - had beneficial effect on lettuce plants

Effect of salicylic acid on cowpea seedlings under saline stress

The aim of this work was applying salicylic acid (SA) in cowpea seedlings under saline stress. The experiment took place in the seed laboratory of the Universidade Federal Rural da Amazônia with a completely randomized experimental design in a 2 x 2 x 3 factorial scheme, with two bean cultivars (Canapu and Pingo-de-ouro), two levels of salicylic acid (0, and 0.50 mM) and three salt stress levels (0, 25, 50 mM). The seeds were previously soaked in salicylic acid (0 and 0.50 mM) for a period of 12 hours and then placed in germitest paper rolls for treatments with NaCl (0, 25, 50 mM) for a period of 12 days at room temperature constant 27 °C. There was a significant effect of cultivars, AS dose and NaCl concentrations and their interactions on most of the analyzed variables. Root and leaf proline concentrations were higher in pingo-de-ouro cultivar, Canapu cultivar had better performance in biomass accumulation. Salicylic acid reduced proteins in the leaves by 13.33%, while in the root there was an increase of 12.61%, ammonium concentrations reduced in the roots by 11.9%. When applied to salinity (25 and 50 mM) there was an increase of proteins in the leaves 40.83% and 27.48% respectively, and a reduction of amino acids of 30.24 and 25.24% in NaCl dosages (25 and 50 mM) respectively. Salinity reduced biomass accumulation and interfered with cellular solute production. However, the application of salicylic acid promoted salt stress tolerance in Canapu cultivar

Parâmetros germinativos em sementes de sorgo submetido a PEG-6000 e NaCl / Germinative parameters in sorghum seeds submitted to PEG-6000 and NaCl

 Fatores abióticos como a deficiência hídrica e a salinidade reduzem a produção do sorgo. Durante a fase germinativa e de estabelecimento da plântula não é diferente, uma vez que a embebição é fundamental em todos os processos fisiológicos e no transporte de substâncias indispensáveis para seu crescimento e desenvolvimento. Mediante a isso, o objetivo do trabalho foi avaliar o efeito do estresse salino e hídrico na germinação de sementes de sorgo, avaliando o comportamento germinativo (porcentagem de germinação, índice de velocidade, tempo médio e a primeira contagem de germinação). O trabalho foi desenvolvido na Universidade Federal Rural da Amazônia (UFRA – Campus Belém), utilizando sementes de sorgo [Sorghum bicolor (L) Moench] cultivar BRS 310. O experimento foi dividido em dois delineamentos inteiramente casualizados separados para cada estresse (hídrico e salino). O primeiro composto por 5 concentrações de NaCl (0,0; 50; 100; 150 e 200 mmol) e o segundo composto por 4 tratamentos (0,0; -0,3; -0,6; -0,9 MPa), no qual as soluções de Polietilenoglicol 6000 simularam tais potenciais osmóticos. A germinação de sementes de sorgo foi comprometida pelo aumento das concentrações de NaCl, assim como a redução dos potenciais osmóticos simulados de PEG-6000. 

QUALIDADE DE SOLO E LITEIRA EM VEGETAÇÃO PÓS MINERAÇÃO E FRAGMENTO FLORESTAL EM CAPITÃO POÇO, PARÁ, BRASIL

The present study aimed to evaluate some chemical and physical attributes of the soil, as well as the litter accumulated above ground in two areas at different fallow times after pebble and sand exploration, compared to a secondary forest. The study was carried out in the municipality of Capitão Poço, Pará, Brazil. Each study area has about 5 ha. The three areas are composed of a forest fragment (FOR), a mined area with fallow of 48 months (DA48) and an area mined in a period of 18 months (DA18). The variables analyzed were soil density, soil particle density, soil fertility and litter physical quality. FOR obtained higher values ​​of litter biomass in almost all factors analyzed. Just the water holding capacity of the litter in this area together with the weight of the fresh straw. In general, it was observed that it is more appropriate to use the fallow observed in the DA18 area for intervention through recovery practices to take advantage of natural regeneration.O presente estudo teve como objetivo avaliar alguns atributos químicos e físicos do solo, bem como a serapilheira acumulada acima do solo em duas áreas em diferentes épocas de pousio após a exploração de seixo e areia, em comparação com uma floresta secundária. O estudo foi realizado no município de Capitão Poço, Pará, Brasil. Cada área de estudo possui cerca de 5 ha. As três áreas são compostas por um fragmento florestal (FOR), uma área minerada com pousio de 48 meses (DA48) e uma área minerada em um período de 18 meses (DA18). As variáveis analisadas foram densidade do solo, densidade de partículas do solo, fertilidade do solo e qualidade física da serapilheira. FOR obteve maiores valores de biomassa de serapilheira em quase todos os fatores analisados. Apenas a capacidade de retenção de água da liteira desta área juntamente com o peso da palha fresca. De modo geral, observou-se que é mais adequado utilizar o pousio observado na área DA18 para intervenção por meio de práticas de recuperação para aproveitar a regeneração natural. Palavras-chave: solos degradados; biomassa vegetal; ecossistemas; recuperação de áreas degradadas; exploração de seixo de areia.   Soil and litter quality under post mining vegetation and forestry fragment in Capitão Poço, Pará, Brazil   ABSTRACT: The present study aimed to evaluate some chemical and physical attributes of the soil, as well as the litter accumulated above ground in two areas at different fallow times after pebble and sand exploration, compared to a secondary forest. The study was carried out in the municipality of Capitão Poço, Pará, Brazil. Each study area has about 5 ha. The three areas are composed of a forest fragment (FOR), a mined area with fallow of 48 months (DA48) and an area mined in a period of 18 months (DA18). The variables analyzed were soil density, soil particle density, soil fertility and litter physical quality. FOR obtained higher values ​​of litter biomass in almost all factors analyzed. Just the water holding capacity of the litter in this area together with the weight of the fresh straw. In general, it was observed that it is more appropriate to use the fallow observed in the DA18 area for intervention through recovery practices to take advantage of natural regeneration. Keywords: degraded soils; vegetal biomass; ecosystem; recovery of degraded lands; pebble and sand exploitation

Silício como mitigador da toxicidade de zinco em plantas jovens de Schizolobium amazonicum Huber ex Ducke

O zinco é um elemento essencial às plantas, entretanto, em excesso pode ser tóxico ao vegetal. A fitorremediação de solo contaminado por Zn é eficaz para reduzir os efeitos tóxicos desse metal ao meio ambiente. Por isso, necessita-se identificar espécies tolerantes a essas condições. O Schizolobium amazonicum é uma espécie arbórea nativa da Amazônia utilizada na recuperação de áreas degradadas. O silício é um elemento benéfico que aumenta a tolerância da planta à estresses bióticos e abióticos. Portanto, o objetivo deste trabalho foi avaliar os efeitos do silício no crescimento, no estado nutricional e na fisiologia de plantas jovens de S. amazonicum submetidas à níveis tóxicos de zinco. Utilizou-se um delineamento em blocos casualizados em esquema fatorial 4 x 2, com quatro concentrações de zinco (1, 150, 300 e 600 µM) e duas concentrações de silício (0 e 1.5 mM) com cinco repetições por 30 dias. Avaliou-se o estado nutricional, o crescimento, a fluorescência da clorofila a, as trocas gasosas e o teor de pigmentos fotossintéticos nas mudas. Os resultados mostraram que os elevados níveis de zinco reduziram o crescimento vegetal, a absorção de nutrientes avaliados e a fotossíntese, com efeitos principalmente associados à limitação fotoquímica e à redução na capacidade de fixação de CO2 no mesófilo, contudo, a aplicação de Si atenuou esse efeito. O S. Amazonicum apresentou baixa translocação e tolerância moderada e alta às concentrações de Zn indicando que está espécie pode ser utilizada como fitoestabilizadora desse metal.Zinc is an essential element for plants, however, in excess it can be toxic to plants. Phytoremediation of soil contaminated by Zn is effective in reducing the toxic effects of this metal on the environment. Therefore, it is necessary to identify species tolerant to these conditions. Schizolobium amazonicum is a tree species native to the Amazon used to recover degraded areas. Silicon is a beneficial element that increases the plant's tolerance to biotic and abiotic stresses. Therefore, the objective of this work was to evaluate the effects of silicon on growth, nutritional status and physiology of young plants of S. amazonicum submitted to toxic levels of zinc. A randomized block design was used in a 4 x 2 factorial scheme, with four concentrations of zinc (1, 150, 300 and 600 µM) and two concentrations of silicon (0 and 1.5 mM) with five repetitions for 30 days. Nutritional status, growth, chlorophyll a fluorescence, gas exchange and photosynthetic pigment content in seedlings were evaluated. The results showed that the high levels of zinc reduced plant growth, the absorption of evaluated nutrients and photosynthesis, with effects mainly associated with the photochemical limitation and the reduction in the capacity of CO2 fixation in the mesophile, however, the application of Si attenuated this It is made. S. Amazonicum showed low translocation and moderate and high tolerance to Zn concentrations, indicating that this species can be used as a phytostabilizer of this metal

GROWTH, YIELD AND POST-HARVEST EVALUATION OF LETTUCE PLANTS SUBJECTED TO DIFFERENT LEAF SILICON CONCENTRATIONS

Lettuce is considered the most produced and consumed leafy vegetable; however, it has short post-harvest life, which generates significant losses for both producers and consumers. Studies have proven the beneficial effect of silicon on fruits and vegetables. Therefore, the aim of the current study is to evaluate the influence of leaf calcium silicate application on the growth, biomass production and postharvest conservation of curly lettuce. The experiment was carried out in greenhouse at Federal Rural University of Amazonia, Parauapebas Campus / PA. It followed a completely randomized design (CRD) with five Si concentrations (0.0, 2.0, 4.0, 6.0 and 8.0 mg L-1) and eight repetitions, which totaled 40 plants. Plants were grown in plastic pots (capacity = 3 dm3) filled with soil classified as Red-Yellow Argisol. Different Si concentrations were applied to plant leaves, at the 20th and 27th days after transplantation (DAT). Silicon has favored the growth and development of lettuce plants, as well as reduced their post-harvest weight loss. It was possible concluding that the herein tested Si concentrations, which were applied to leaves - in the form of calcium silicate - had beneficial effect on lettuce plants