Cálcio e fitorreguladores no desenvolvimento e estado nutricional de Mentha spicata x suaveolens cultivada em solução nutritiva / Calcium and plant growth regulators on the development and nutritional status of Mentha spicata x suaveolens cultivated in nutrient solution

O trabalho teve como objetivo estudar o desenvolvimento e o estado nutricional de Mentha spicata x suaveolens cultivada em diferentes níveis de Calcio em solução nutritiva com aplicação de fitorreguladores. O experimento constou de esquema fatorial (4x4) sendo quatro níveis de Ca2+ na solução nutritiva (160, 120, 80 e 40 mg L-1) e três aplicações foliares, com intervalos de 15 dias, de ácido naftaleno acético (NAA), ácido giberélico (GA3), benzinaladenina (BA) e água destilada como testemunha. As plantas foram coletadas 60 dias após a transferência para a solução e avaliadas as variáveis, matéria fresca e seca, área foliar e número de folhas; volume, comprimento e superfície radiculares e teores de Ca, K, Mg, N e P das folhas. As variáveis foram submetidas à análise de variância e as médias comparadas pelo teste Tukey. Não foram encontradas diferenças entre os níveis de Ca para a produção de biomassa. A auxina não influenciou a matéria seca das plantas, embora tenha aumentado os teores foliares de Ca; a citocinina acarretou diminuição da matéria seca total e a giberelina aumento da matéria seca do caule. A variação de Ca2+ não influenciou os teores foliares de N, P, K e Mg. Houve resposta para aplicação de Ca2+, com teores foliares atingindo o máximo de 15,73 mg kg-1 na dose de 137,81 mg L-1 pela análise de regressão

This study aimed to verify the development and the nutritional status of Mentha spicata x suaveolens cultivated under different Ca2+ levels in nutrient solution with application of plant growth regulators. The experiment was in factorial design (4X4) with four Ca2+ levels in the nutrient solution (160, 120, 80 and 40 mg L-1) and three leaf applications, at 15-day intervals, of naphthalene acetic acid (NAA), gibberellic acid (GA3), benzyladenine (BA) and distilled water as control. Plants were harvested at 60 days after transferring to the nutrient solution and the following variables were evaluated fresh and dried matter, leaf area, number of leaves, volume, length and surface of roots, and leaf content of Ca, K, Mg, N and P. The variables were subjected to analysis of variance and means compared by Tukey's test. There were no differences between Ca levels for biomass production. The auxin did not influence the dry matter of plants although it increased the leaf content of Ca2+, the cytokinin reduced total dry matter and the gibberellin increased the stem dry matter. The change in Ca2+ did not influence the leaf content of N, P, K and Mg. There was response for the application of Ca2+, reaching the maximum of 15.73 mg L-1 leaf content at the level of 137.81 mg L-1, according to regression analysis

Effect of phytohormone pretreatment on metabolic changes in Vigna radiata under salt stress.

Efficiency of pretreatment as foliar spray of indole-3-acetic acid, gibberellic acid and kinetin (6-furfuryl aminopurine) each ranging from 10(-7) to 10(-5) M in restoring the metabolic alterations imposed by NaCl salinity (E.C. value 4.0 m mhos/cm) was investigated in Vigna radiata (L.) Wilczek. Application of NaCl resulted in about 7% and 9% decrease in phenol content in mung bean leaf and root respectively. In leaf, NaCl caused 40% increase in polyphenol oxidase enzyme activity over the control set. This effect was accentuated in root, where salinity caused 200% increase in the enzyme activity. In leaf and root of mung-bean plant, ascorbic acid content decreased about 29% and 31% respectively under salinity stress as compared with control. Ascorbic acid oxidase enzyme activity increased under stress by about 55% and 23% respectively in leaf and root. It was noted that all the three growth regulators used in the present study were able to overcome to variable extents the adverse effects of stress imposed by NaCl solution.