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Cloreto de potássio e fosfato de sódio na multiplicação in vitro de amoreira-preta cv. Tupy

A micropropagacao da amoreira-preta pode gerar plantas livres de virus e em curto espaco de tempo. Com o objetivo de aprimorar tecnicas de micropropagacao de amoreira-preta cv. Tupy (Rubus spp.), segmentos nodais com cerca 2 cm e 2 gemas axilares, oriundos de plantas pre estabelecidas in vitro, foram excisados e inoculados em meio de cultura MS, suplementado com diferentes concentracoes de fosfato de sodio (0, 125, 250, 500 e 1000 mg L-1) e de cloreto de potassio (0, 125, 250, 500 e 1000 mg L-1). O pH foi ajustado para 5,8 antes da adicao de 6 g L-1 de agar e da autoclavagem a 121oC e 1 atm por 20 minutos. Apos a inoculacao, os explantes foram transferidos para sala de crescimento a 25 ± 1oC, irradiância de 35 mmol m-2 s-1 e fotoperiodo de 16 horas, onde permaneceram por 60 dias. O delineamento experimental utilizado foi inteiramente casualisado, utilizando-se de quatro repeticoes constituidas de tres tubos de ensaio contendo um explante cada. O numero de brotos e o comprimento da parte aerea das plantas foi menor em funcao de maiores concentracoes de cloreto de potassio. Melhores resultados foram obtidos na ausencia de KCl e na presenca de fosfato de sodio, principalmente para comprimento e materia fresca da parte aerea.

Cloreto de sódio e ácido naftalenoacético no enraizamento de microestacas de amoreira-preta cv. Brazos in vitro

The blackberry (Rubus sp.) micropropagation is used, mainly for obtaining virus-free plants in short period of time. In the present work different concentrations of sodium chloride (NaCl) and naphthaleneacetic acid (NAA) were tested added to in vitro culture medium of blackberry cv. Brazos. The culture medium consisted of MS salts, with 30 g L-1 sucrose 6 g L-1 agar and pH adjusted to 5.8 before the sterilization at 121oC and 1 atm for 20 minutes. The treatments consisted of NaCl (0; 25; 50; 75 and 100 mg L-1) and NAA (0; 0.01; 0.5; 1.0 and 1.5 mg L-1) concentrations, in all possible combinations. Nodal segments, originating from plants established in vitro were excised and introduced in tubes containing 15 mL of culture medium. After that, the tubes were transferred to growth room at 25 ± 2oC, irradiance of 35 mmol m-2 s-1 and photoperiod 16 hours. A completely randomizel block design with four replicates and 12 plants per replicate was used. The experiment was evaluated after 70 days of in vitro cultivation. The in vitro development of the cv. Brazos was favored in the treatments with 50 to 75 mg L-1 NaCl and 1.0 to 1.5 mg L-1 NAA, while the best rooting results were obtained using 100 mg L-1 NaCl and 1.5 mg L-1 NAA.

Effects of Shade on Individual Ramet Growth and on Clonal Growth of the Aquatic Fern Salvinia auriculata (Salviniaceae)

Abstract Light intensity is among the major environmental factors determining the ecological distribution of any plant. The effects of light availability on aquatic plants continue to be discussed, as some species show higher growth under full sun conditions and other species show reduced growth. The aim of this study was to test the effects of different shade levels on ramets and clonal growth of the fern Salvinia auriculata. We hypothesized that the ramets grow better under shade conditions over time as in most land ferns. We performed a greenhouse experiment, putting plants under three treatments: control (0% shade), 30% shade, and 70% shade. We monitored the growth of individual ramets as well as clonal spread for 30 days. The number of new ramets (clonal growth) increased exponentially in the three treatments, however this number was higher in shade than in full sun plots. The size of floating leaves, submerged leaves, and rhizomes was higher under shade treatments compared to individuals under sun treatment. Our results showed that S. auriculata has a high growth performance under shade environments, including both clonal growth and the size of individual ramets, similar to most land ferns. This species appears highly plastic as it also thrives under bright sun, which appears to be a consistent pattern among fern species in both terrestrial and aquatic environments. Because shade has been proposed as a treatment to control and manage aquatic plants, application of this treatment should be carefully considered depending of the species, especially when it involves aquatic fern species.