Plant development, gas exchanges and pigments of Mesosphaerum suaveolens submitted to osmoconditioning and saline stress

Salinity is one of the main plant abiotic stresses affecting the establishment and development of crops. It is thus a matter of prime importance to search for technologies that minimize the damage caused by salinity. The aim of the present work was to evaluate the effect of salinity stress and osmotic conditioning of seeds on the biomass, gas exchanges and chlorophyll pigments in Mesosphaerum suaveolens (L.) Kuntze. The statistical design adopted was a randomized block design, combined according to the central composite design, referring to electrical conductivities of irrigation water and osmotic potentials, with minimum (- α) and maximum (α) values of 0.5 and 10.0 dS m-1 and 0.0 and -1.0 MPa, respectively, totaling nine combinations. The characteristics of dry biomass, gas exchange and chlorophyll indices were evaluated at 45 days after the beginning of irrigation with saline water. The salinity of irrigation water severely affected the dry biomass and the gas exchanges of M. suaveolens. Irrigation water of electrical conductivity above 3.2 dS m-1 caused reductions in chlorophyll a, b and total contents in M. suaveolens plants. Seed osmoconditioning did not attenuate the negative effects of saline stress on M. suaveolens plants

Initial growth of Moringa oleifera Lam. as a function of poultry litter doses and granulometry

There is an increasing use of poultry litter in seedling production. However, studies regarding the effect of different particle-size litter on plant growth are still scarce. This study aimed to evaluate the growth of Moringa oleifera Lam. fertilized with poultry litter doses (0 g dm-3, 40 g dm-3, 80 g dm-3 and 120 g dm-3) with distinct particle sizes (1 mm and 4 mm), with four replications. The following variables were evaluated: plant height; root and stem diameter; leaf, stem, shoot and root dry matter mass; shoot/root dry matter mass ratio; and the Dickson quality index. There was no influence of the particle size on the studied variables, except for plant height. The root diameter decreased with the increase of the poultry litter doses. The accumulation of dry matter mass from the shoot and root increased with the increase of poultry litter doses up to 120 g dm-3. A linear increase of the Dickson quality index, relatively to days and poultry litter doses, was observed. It is recommended to apply 80 g dm-3 of poultry litter to fertilize M. oleifera plants, independently of the granulometry used

Photochemical efficiency and growth of sugar apple under irrigation with saline water and foliar nitrogen

Salt stress has compromised the worldwide expansion of fruit farming by causing damage to light energy regulation and crop growth, which can be mitigated by applying foliar nitrogen (N). From this perspective, this study aimed to evaluate the chlorophyll contents, fluorescence, and the growth of sugar apple seedlings under irrigation with saline water and foliar N fertilisation. The experiment was conducted in a plant nursery and following a randomized block design referring to five electrical conductivity levels of irrigation water (0.5, 1.15, 2.75, 4.35, and 5.0 dS m-1) and five foliar N levels (0.0, 0.33, 1.15, 1.97, and 2.3 g L-1), with four replications and two plants per plot, totaling nine combinations generated by the Box central composite design. Irrigation water salinity reduces the growth of sugar apple seedlings irrigated with conductivity levels over 1.7 dS m-1 at 90 days after emergence. Foliar N fertilisation increased the photochemical efficiency and growth of sugar apple seedlings. The foliar application of 1.93 g L-1 mitigate the deleterious effects of water salinity on the photochemical efficiency and growth of sugar apple seedlings

Basil (Ocimum basilicum) growth under saline stress and salicylic acid

443-449Basil (Ocimum basilicum L.) is an aromatic and spice plant used around the world in cooking, pharmaceutical, cosmetic and flavoring industries. Salicylic acid has been used to mitigate the deleterious effects of salinity on plants. This work aimed to evaluate the growth of basil under saline stress and salicylic acid. A randomized block design was used. Five electrical conductivities of irrigation water (ECw - 0.5, 1.3; 3.25; 5.2 and 6.0 dS m-1) and five salicylic acid doses (SA - 0.0, 0.29, 1.0, 1.71 and 2.0 mM) was used. Plant height, number of leaves, stem diameter, leaf area, specific leaf area, relative growth rate, leaf area ratio, leaf mass ratio, relative leaf growth rate and chlorophyll a, b and total indices were evaluated at 32, 39, 46, 53 and 60 days after irrigation with saline water (DAI). The increase in the electrical conductivity of irrigation water (ECw) negatively affected growth and increased the basil chlorophyll index. The application of salicylic acid attenuated the negative effects of salt stress on the number of leaves and leaf area and had negative effects on the stem diameter, but did not affect the other growth variables and chlorophyll indices

Physiological and Biochemical Changes in Immature Seeds of Tabebuia caraiba During Storage

Abstract Studies about the viability and vigor of seeds during storage, especially on the characterization of enzymatic changes, may increase the harvesting efficiency of immature seeds and guarantee their viability for a prolonged period. Therefore, this study aimed to evaluate the behavior of immature seeds of Tabebuia caraiba during storage. For this, thirty selected mother plants at the anthesis stage located in São João do Cariri and Sumé, Paraíba, Brazil were selected. Flowers of each tree were marked, and the fruits were harvested at 35, 42, and 49 days after anthesis (DAA) and characterized according to their maturation stages. The seeds from each maturation stage and city were packed in paper bags and stored in a refrigerator (6 ± 2 °C) for 360 days. The seed quality, seedling vigor, and enzymatic activity of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX) were evaluated at the beginning of the storage period and intervals of 90 days. The seeds of T. caraiba harvested at 35, 42, and 49 DAA maintained high viability for 360 days of storage. T. caraiba seeds stored for 360 days withstood with high vigor when harvested at 42 DAA. The CAT, SOD, and POX activity was correlated to the deterioration process of the seeds under storage conditions

Physiological changes in Solanum lycopersicum L. in the presence of root-knot nematodes and salicylic acid

Nematodes of the genus Meloidogyne spp. are one of the tomato culture’s main pathogens. According to their soil infestation level, physiological changes may occur. Consequently, it is extremely important to employ given products to minimize their effect. A feasible option is the salicylic acid, a phytohormone that can induce into resistance due to its ability to increase the production level of some pathogenicity proteins. Therefore, the purpose hereof was to assess the effect of salicylic acid on the physiology of tomato plants subject to different populational densities of Meloidogyne javanica. The design employed was one of randomized blocks, in an incomplete factorial scheme, using the Box Central Compound (BCC) matrix with five nematode populational densities (PD) (0; 5815; 20000; 34184; and 40000 eggs per plant) and five salicylic acid doses (0.0; 0.29; 1.0; 1.71; and 2.0 mM), with four repetitions and two plants per experimental patch. The gas exchanges, fluorescence, and chlorophyll levels were evaluated 45 days after the transplant and soil infestation. The data were submitted for analysis of variance through the F test and, in the significance cases, the polynomial regression analysis was performed. For stomatal conductance, a greater reduction was seen at the PD of 21755 eggs per plant, a fact that might have decreased the liquid assimilation of CO2 and the efficiency of carboxylation. The salicylic acid (SA) affected the CO2 liquid assimilation and the efficiency of carboxylation. The infestation of M. javanica in tomato plants negatively affected the gas exchange and the chlorophyll levels because the SA application did not mitigate the negative effect thereof

FITOMASSA E CRESCIMENTO DE MANJERICÃO ROXO IRRIGADO COM ÁGUA SALINA SOB ADUBAÇÃO FOLIAR NITROGENADA

Basil is a species with high exploitation potential. However, its production in semiarid regions is compromised due to the salts contained in the soil and in the water used in irrigation, requiring the adoption of techniques that increase the tolerance of plants to salinity, such as nitrogen fertilization. Thus, this study aimed to evaluate the effect of leaf nitrogen fertilization on growth and phytomass allocation in purple basil plants under irrigation with saline water. The experiment was carried out in a randomized block design in an incomplete factorial scheme, with five levels of salinity (0.0; 0.81; 2.75; 4.69 and 5.50 dS m-1) and five levels of nitrogen (0.00; 58.58; 200.00; 341.42 and 400.00 mg L-1). Leaf succulence, sclerophilia index and shoot dry mass production, stem, leaf and root dry mass allocation, specific leaf area and leaf area ratio were evaluated. Foliar application of N attenuated the effects of salt stress on phytomass allocation, leaf succulence and shoot phytomass production index. N and salinity increased the specific leaf area and leaf area ratio in basil plants.O manjericão é uma espécie de elevado potencial de exploração. No entanto, sua produção em regiões semiáridas é comprometida decorrentes dos sais contidos no solo e na água utilizada na irrigação, sendo necessário a adoção de técnicas que aumente a tolerância das plantas a salinidade, como a fertilização com nitrogênio. Assim, objetivou-se avaliar o efeito da adubação nitrogenada foliar no crescimento e na alocação de fitomassa em plantas de manjericão roxo sob irrigação com águas salinas. O experimento foi realizado em delineamento de blocos casualizados em esquema fatorial incompleto, constando com cinco níveis de salinidade (0,0; 0,81; 2,75; 4,69 e 5,50 dS m-1) e cinco doses de nitrogênio (0,00; 58,58; 200,00; 341,42 e 400,00 mg L-1). Avaliou-se a suculência foliar, os índices de esclerofilia e de produção de fitomassa seca da parte aérea, alocação de fitomassa seca do caule, das folhas e da raiz, área foliar específica e razão de área foliar. A aplicação foliar de N atenuou os efeitos do estresse salino sobre a alocação de fitomassa, suculência foliar e no índice de produção de fitomassa da parte aérea. O N e a salinidade aumentou a área foliar específica e a razão de área foliar nas plantas de manjericão. Palavras-chave: estresse salino; Ocimum basilicum L.; nitrogênio.   Phytomass  and growth of purple basil irrigated with saline water under nitrogen foliar fertilization   ABSTRACT: Basil is a species with high exploitation potential. However, its production in semiarid regions is compromised due to the salts contained in the soil and in the water used in irrigation, requiring the adoption of techniques that increase the tolerance of plants to salinity, such as nitrogen fertilization. Thus, this study aimed to evaluate the effect of leaf nitrogen fertilization on growth and phytomass allocation in purple basil plants under irrigation with saline water. The experiment was carried out in a randomized block design in an incomplete factorial scheme, with five levels of salinity (0.0; 0.81; 2.75; 4.69 and 5.50 dS m-1) and five levels of nitrogen (0.00; 58.58; 200.00; 341.42 and 400.00 mg L-1). Leaf succulence, sclerophilia index and shoot dry mass production, stem, leaf and root dry mass allocation, specific leaf area and leaf area ratio were evaluated. Foliar application of N attenuated the effects of salt stress on phytomass allocation, leaf succulence and shoot phytomass production index. N and salinity increased the specific leaf area and leaf area ratio in basil plants. Keywords: salt stress, Ocimum basilicum L.; nitrogen

Morfofisiologia e componentes de produção de mini-melancia sob níveis de reposição hídrica e adubação nitrogenada

No semiárido do Nordeste do Brasil, a irregularidade de chuvas e elevada evapotranspiração proporcionam déficit hídrico nas plantas na maior parte dos meses do ano, destacando-se como fator limitante para produção de olerícolas. Assim, a identificação de estratégias capazes de amenizar os efeitos do déficit hídrico nas plantas é essencial para produção sob condições irrigadas. Nesse contexto, objetivou-se avaliar o efeito da adubação nitrogenada na morfofisiologia e nos componentes de produção de mini-melancia 'Sugar Baby'. O experimento foi conduzido na Fazenda Experimental ‘Rolando Rivas Castellón’, São Domingos, Paraíba, sob condições de casa de vegetação, utilizando-se o delineamento de blocos casualizados em esquema fatorial 4 × 4, correspondendo a quatro níveis de reposição hídrica (50, 75, 100 - controle e 125% da evapotranspiração real da cultura - ETr) e quatro doses de nitrogênio - DN (50, 75, 100 e 125% da dose recomendada), com 3 repetições, totalizando 48 plantas. Foram avaliadas as variáveis de trocas gasosas, os teores de pigmentos fotossintéticos, o conteúdo relativo de água e o extravasamento de eletrólitos, o crescimento e a produção de fitomassa, os componentes de produção e a qualidade pós-colheita dos frutos de mini-melancia. A irrigação deficitária com 50% da evapotranspiração real inibiu as trocas gasosas, a síntese de pigmentos fotossintéticos, o crescimento, e a qualidade dos frutos da mini-melancieira ‘Sugar Baby’, independente da dose de nitrogênio. A lâmina de água com 125% da evapotranspiração real combinada à adubação de 100% da recomendação de nitrogênio proporcionou maiores teores de clorofilas totais, número de folhas e de fitomassa seca das raízes, caule, total, parte aérea e pH dos frutos de mini-melancieira ‘Sugar Baby’

Peróxido de hidrogênio na indução de tolerância de mudas de goiabeira ao estresse salino

A goiabeira é uma cultura importante no cenário socioeconômico da região semiárida brasileira, sendo uma fonte de geração de emprego e renda. Contudo, nesta região é comum a ocorrência de fontes hídricas com altos teores de sais dissolvidos e assim são necessárias estratégias que visem minimizar os efeitos deletérios do estresse salino nas plantas. Neste contexto, objetivou-se com este trabalho avaliar os efeitos da aplicação foliar com peróxido de hidrogênio nas trocas gasosas, eficiência fotoquímica, crescimento e qualidade de mudas de goiabeira sob estresse salino. O experimento foi conduzido sob condições de casa de vegetação em Pombal, Paraíba, utilizando-se o delineamento de blocos casualizados, com tratamentos arranjados em esquema fatorial 5 × 4 , referentes a cinco níveis de condutividade elétrica da água - CEa (0,3; 1,3; 2,3; 3,3 e 4,3 dS m-1) e quatro concentrações de peróxido de hidrogênio – H2O2 (0, 25, 50 e 75 μM) com quatro repetições e duas plantas por parcela. A irrigação com água de condutividade elétrica a partir de 0,3 dS m-1 inibiu as trocas gasosas, eficiência fotoquímica e crescimento de mudas de goiabeira, aos 91 dias após a emergência. A aplicação foliar de peróxido de hidrogênio em concentrações de até 75 μM não amenizou os efeitos do estresse salino em plantas de goiabeira na fase de formação de mudas. A goiabeira cv. Paluma é classificada como sensível a salinidade da água na fase de formação de mudas, sendo o nível limiar de 0,3 dS m-1 e diminuição por aumento unitário de 11,48%