Pumpkin (Curcubita moschata Duchesne) production in quantity and quality is often restricted due to adverse environmental conditions. Thus, the objective was to evaluate the action of phytohormones as stress attenuators on the germination and initial growth of pumpkin seedlings, cv. Sergipana, under different types of water. The design adopted was completely randomized, in a 3 × 4 factorial scheme, with four repetitions. In addition to the control, the seeds were treated with the gibberellic and salicylic acids and irrigated with the supply water, fish farming wastewater, artesian well water and solution of the mixture of fish farming wastewater + artesian well water, in a 1:1 ratio. The variables evaluated were germination, first germination count, germination speed index, length of shoots and roots, dry mass of shoots and roots, soluble sugars, amino acids and proline. Treatment of pumpkin seeds, cv. Sergipana, with gibberellic and salicylic acids improved germination kinetics and attenuated the effects of water salinity during the initial growth of pumpkin seedlings.

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.

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.

A nutrição mineral é fator determinante no enraizamento adventício, com envolvimento nas respostas morfogenéticas, processos bioquímicos e fisiológicos. A influência dos minerais sobre o sucesso do enraizamento apresenta correlação com o estado nutricional da planta matriz doadora, pois esta determina a quantidade de carboidratos, hormônios e outros compostos metabólicos essenciais para induzir o desenvolvimento radicular e vegetativo. Embora o enraizamento e a nutrição mineral estejam intimamente relacionados, poucos estudos têm sido divulgados visando à caracterização dos efeitos de nutrientes específicos. Neste contexto, realizou-se, com base em informações disponíveis na literatura, uma análise do papel de alguns nutrientes envolvidos na rizogênese adventícia de espécies cultivadas via propagação vegetativa. Com isso, é pertinente considerar que se o nutriente estiver envolvido nos processos metabólicos da planta e possibilitar a desdiferenciação para formação do meristema radicular, este é essencial para rizogênese. Dessa forma, infere-se que o nitrogênio, fósforo, zinco e boro são elementos necessários para algumas espécies durante o processo de propagação vegetativa por participarem diretamente do processo de enraizamento.

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