Salicylic acid (SA) may induce toxicity in orchids depending on its concentration and the plant species, but there is no information about the effect of this substance on orchids cultivated in vitro. The objective of the present study was to evaluate the effects of different concentrations of SA on Cymbidium atropurpureo and Phalaenopsis Golden Peoker cultivated in vitro to verify the biological losses caused by the substance’s toxicity. The orchids Cymbidium atropurpureo and Phalaenopsis Golden Peoker were sown in vitro in a Murashige and Skoog (MS)-growth medium and transferred to a medium of the same type containing SA 90 days after sowing. The studied SA concentrations were 0, 50, 100, 200, 300, 400, 500, and 1000 µmol·L−1, and the plants were kept in this medium for 210 days. The treatments were distributed into a completely randomized design with four replications. Biometric variables of the seedlings and electrolyte leakage were evaluated 300 days after sowing. The results indicate that the addition of SA interfered with the in vitro growth and development of seedlings of Cymbidium atropurpureo and Phalaenopsis Golden Peoker, given that it caused all the examined variables to show reduced values and triggered electrolyte leakage, consequently inducing toxicity.
Cibele Mantovani, Jonas Pereira de Souza Júnior, Renato de Mello Prado and Kathia Fernandes Lopes Pivetta
Valéria Santos Cavalcante, Renato de Mello Prado, Ricardo de Lima Vasconcelos, Hilário Júnior de Almeida and Thais Ramos da Silva
Biological damage caused by macronutrient deficiency in watermelon plants is still not known, and may lead to nutritional disorders and alterations in absorption and utilization efficiencies, depending on the evaluated nutrient. In this context, the aim of the present study was to evaluate the growth and nutritional efficiency of watermelon plants grown under macronutrient deficiencies. The experiments were carried out in pots containing an aerated nutrient solution. Treatments consisted of the nutrient solution containing (control) or lacking nitrogen (−N), phosphorus (−P), potassium (−K), calcium (−Ca), magnesium (−Mg), and sulfur (−S), in a completely randomized design with three replications. At the end of the experiment with the onset of symptoms of deficiency, plant growth, green color index, nutrient accumulation, nutrient uptake, nutrient utilization efficiency, root density, and foliar deficiency symptoms were evaluated. P, K, Ca, Mg, and S deficiencies increased plant utilization efficiency and can potentiate watermelon development in environments deficient in these nutrients. The opposite was observed concerning nitrogen deficiency, because this condition induced greater biological damage, with low utilization efficiency, indicating the sensitivity of this species in low N conditions.
Sylvia Letícia Oliveira Silva, Renato de Mello Prado, Gilmara Pereira da Silva, Gabriel Barbosa da Silva Júnior, Monica Lanzoni Rossi and Leónides Castellanos González
This study aimed to evaluate the effects of boron (B) omission on cowpea nutrition and to compare the impact of foliar B fertilization with and without sorbitol on cowpea growth, nutritional status, and B uptake. Two trials using a completely randomized experimental design were conducted. During the first experiment, nutrient solution was provided without B (−B) and with B (+B) in 10 replicates. During the second experiment, a 5 × 2 factorial treatment scheme was used. Five B concentrations (0, 1.25, 2.5, 3.75, and 5.0 g·L−1) were administered foliarly in the form of boric acid with or without sorbitol (500 mmol·L−1) in four replicates. B omission symptoms, root growth, plant organ dry mass and B content, and grain yield were evaluated. B omission induced greater losses in reproductive organ and root growth than in leaf and stem production. It also caused deformation of the middle lamella and accumulation of starch in the chloroplasts. Foliar applications of 2.6 to 2.9 g·L−1 B improved cowpea production. The addition of sorbitol did not enhance plant growth. However, it increased B absorption in the vegetative parts of the plant but did not enhance seed production.