Caio César Pereira Leal

Melon production in the Brazilian semi-arid region is subject to the use of marginal waters with high salinity. However, the use of regulators and bioactivators in seed treatment can mitigate the harmful effects of salts in irrigation water. In this context, the objective was to evaluate the effect of pre-germination treatments with plant regulators and bioactivator in melon seeds for the production of seedlings irrigated with biosaline water from fish farming effluent. For this, two trials with the Goldex and Grand Prix hybrids were carried out separately. A completely randomized design was used in a 4 × 3 factorial scheme (pre-germination treatments × water dilutions). In addition to the control, the seeds were treated with salicylic and gibberellic acids and thiamethoxam. The waters used for irrigation were local-supply water, fish farming effluent (biosaline water) and these diluted to 50%. Physiological and biochemical analyses were performed for fourteen days. Biosaline water (5.0 dS m^-1) did not affect the emergence of Goldex melon seedlings, but compromised the establishment of the Grand Prix cultivar. Seed pre-treatments with salicylic and gibberellic acids attenuate the effects of water salinity and promote growth modulations, resulting in more vigorous melon seedlings.

The scarcity of surface water has led to the use of underground sources as an alternative for crop irrigation by farmers in semi-arid regions. However, these water sources generally have high salinity, which prevents agricultural production. The objective of this study was to determine the effects of pre-germination treatments with plant growth regulators and bioactivators on melon seeds to attenuate salt stress caused by irrigation water during germination and seedling development. Two trials were carried out separately with the hybrids, Goldex and Grand Prix. The design was completely randomized in a 4 × 3 factorial scheme (four seed treatments and three dilutions of irrigation water). Seeds were treated with salicylic acid and gibberellic acid and the insecticide, thiamethoxam, in addition to the control. Local supply water, artesian well groundwater, and dilution of these waters at a 1:1 ratio were employed for irrigation. Fourteen days after sowing, morphological and physiological analyses were performed, and the material was collected for biochemical determination. The use of saline well water affected the initial development of melon seedlings of the Goldex and Grand Prix hybrids. Pre-germination treatment of Goldex hybrid seeds with gibberellic acid was inefficient at mitigating salt stress. However, the effects of irrigation water salinity on Grand Prix melon seeds pretreated with salicylic acid and thiamethoxam were attenuated.

A Revista Ciência Agronômica é voltada para estudos relacionados com as Ciências Rurais e Recursos Naturais

Pityrocarpa moniliformis Benth. has medicinal properties, forage potential, besides showing rusticity and rapid growth, which confer potential to recover degraded areas. In this context, the objective was to evaluate the growth and biochemical components of Pityrocarpa moniliformis seedlings under water deficit conditions. The design used was randomized blocks, with five treatments and four replicates, with the experimental plot consisting of twenty plants. Treatments were characterized by different periods of water deficit (0; 4; 8; 12 and 16 days without irrigation). At 44 days after sowing (DAS), when the seedlings had two pairs of fully formed true leaves, the treatments began to be applied. The development of the seedlings was evaluated until 60 DAS when they were collected for biometric and biochemical analyses. The variables analyzed were shoot height; collar diameter; number of leaves; shoot dry mass; root dry mass; root/shoot ratio; and Dickson’s quality index. Contents of total chlorophyll, chlorophyll a, chlorophyll b, total free amino acids, total soluble sugar, and proline contents in the leaves were also determined. The treatment most affected by the lack of irrigation was 16 days of water deficit, which resulted in the death of 38.8% of the seedlings. This condition caused a decrease in shoot length, reducing it by approximately 29.2% compared to the control treatment. There was also a reduction in the production of new leaves from the eighth day after the differentiation of treatments. Pityrocarpa moniliformis seedlings can develop under the condition of water deficit for up to 8 days, even with chlorophyll degradation due to stress. Pityrocarpa moniliformis maintains its vegetative development by performing osmotic adjustment through the accumulation of biomolecules (sugars, proline, and amino acids).

Saline irrigation water at high levels causes disturbance in the growth of more sensitive plants. The objective of this research was to evaluate the initial growth of Pityrocarpa moniliformis seedlings under different electrical conductivity in irrigation water through physiological and biochemical analyses. The experiment was conducted in a greenhouse with five water electrical conductivities (0.5, 2.0, 4.0, 6.0 and 8.0 dS m-1) and four repetitions of 20 plants each, arranged in a randomized block design. Application of the treatments with irrigation water containing NaCl began at 30 days after sowing. To determine the behaviour of the species, the following variables were analysed: stem diameter, plant height, number of leaves, leaf area, Dickson quality index, shoot dry mass, root dry mass and total dry mass, as well as the biochemical variables, such as the concentrations of total soluble sugars, free proline and chlorophylls a and b. The increase in irrigation water salinity hampered the growth of P. moniliformis seedlings, with electrical conductivity of 0.5 dS m-1 being the limit for maximum production. The results also indicated that the deleterious effects of salt stress on P. moniliformis seedlings variables increase in concentrations of proline, total soluble sugars and betaine glycine.

“Mofumbo” (Combretum leprosum Mart. (Combretaceae) is a neotropical species of wood, pharmacological, beekeeping and environmental importance. Thus, the objective was to evaluate the biochemical and physiological responses in C. leprosum seeds under different storage environments. The experiment was carried out in a factorial (2 x 7), with two storage conditions (natural and climate-controlled environments) and seven storage periods (0; 60; 120; 180; 240; 300 and 360 days), in four replications per treatment. At the beginning of storage and at 60-day intervals, the seeds were analyzed for water content, physiological potential (germination, germination speed index, root and shoot lengths and seedling dry mass) and biochemical (neutral lipids, lipid peroxidation, total and reducing sugars, total free amino acids, and starch). The results indicated that storing “mofumbo” seeds for 360 days reduced viability, being more pronounced after 180 days, regardless of the storage environment. “Mofumbo” seeds were stored in a natural environment for 180 days, resulting in less lipid degradation. After this period, the reduction was associated with the attack of reducing sugars on amino acids. Thus, it is concluded that “mofumbo” seeds must be stored in a natural environment for up to 180 days.

A Piptadenia stipulacea Benth., conhecida popularmente como jurema-branca, é uma espécie arbórea de pequeno porte, nativa da Caatinga, amplamente distribuída na região Nordeste do Brasil, sendo considerada de grande interesse comercial, econômico e ambiental para a região pelas suas características de uso múltiplo. O presente trabalho teve com o objetivo avaliar o efeito de diferentes concentrações salinas em água de irrigação na emergência e desenvolvimento inicial de plântulas de jurema-branca. O delineamento estatístico utilizado foi o inteiramente casualizado, com sete tratamentos e quatro repetições, com 25 sementes cada. Os tratamentos consistiram das concentrações salinas (0,5; 1,5; 2,5; 3,5; 4,5; 5,5 e 6,5 dS m-¹), que foram obtidas através da adição de NaCl em água de forma que as soluções fossem calibradas para as condutividades elétricas pré-estabelecidas. As variáveis avaliadas foram a porcentagem de emergência, velocidade de emergência, altura de plântula, número de folhas, comprimento de raiz e massa seca da parte aérea, raiz e total. A espécie possui tolerância moderada a salinidade, suportando salinidades de 4,5 dS m-¹ sem que haja perdas significativas de germinação e número de folhas. No entanto, a irrigação com água salina afeta de forma negativa as plântulas de jurema-branca, comprometendo seu desenvolvimento quanto ao acúmulo de massa e crescimento da parte aérea.

Water scarcity in the world is a problem diagnosed especially in countries with large semi-arid regions such as Brazil. Research has been conducted with a view to making use of saline waters as an input for cultivation, particularly in hydroponics, with especial focus on lettuce, the most prominent leafy vegetable in Brazil. The objective of this study was to evaluate the development of lettuce in a semi-hydroponic system fertigated with saline water and under foliar fertilization with biofertilizer. The present study was carried out in a greenhouse located in the experimental area of ​​the Department of Environmental and Technological Sciences (DCAT) of the Federal Rural University of the Semi-Arid Region, in the municipality of Mossoró, RN, Brazil. The experimental design was a randomized complete block design, with treatments arranged in a 2 x 4 factorial scheme, with 4 replicates, two salinity levels of the water used to prepare the nutrient solution (0.5 and 3.5 dS m-1) and four biofertilizer concentrations (0, 20, 40 and 60%) applied by foliar spraying. The evaluated characteristics were: shoot diameter, stem diameter, number of leaves, fresh mass, dry mass, leaf succulence, leaf area and specific leaf area. The use of saline water to prepare the nutrient solution reduces fresh mass and dry mass production in the lettuce crop. The biofertilizer can be applied through the leaves at concentration of up to 20%, promoting greater plant growth.

1. INTRODUCTION AND OBJECTIVES