Polysulfides Applied as Formulated Garlic Extract to Protect Tomato Plants against the Root-Knot Nematode Meloidogyne incognita

The devastating root-knot nematode Meloidogyne incognita can cause severe damage to field and greenhouse crops. Due to high economic losses, alternative products are essential to replace banned or strictly regulated nematicides that affect human health and/or the environment. Garlic based products have been previously investigated as environmentally friendly nematicides and their active substances, diallyl polysulfides exist as formulated nematicides on the market. We tested the garlic-based nematicide NEMguard® DE as protective of tomato roots. In vitro evaluation of the lethal concentration (LC) showed strong nematicidal activity with LC50 of 0.8 mg/mL after 96 h and LC90 of 1.5 mg/mL. NEMguard® DE showed protective effect against M. incognita as a single application in small pots and a second application further reduced root galling, significantly. Large greenhouse trials were carried out in two consecutive years to test single and monthly applications of NEMguard® DE. In both years, no controlling effect could be observed on M.incognita. We assume that the silt content of the loamy sandy soil used had an effect on the polysulfides, inhibiting their nematicidal effect. We conclude that further experiments are necessary to investigate the nematicidal potential of NEMguard® DE under different soil compositions or as a different formulation.

Effect of natural auxin from portulaca grandiflora hook and Ipomoea batatas (L.) Poir on the formation adventitious roots in vitro of Plumbago zeylanica L.

Plumbago zeylanica L. is a traditional herbal that has been reported to treat on skin diseases. Furthermore, some researchers have found plumbagin extracted from roots of this species can prevent cancer cell development. In current study, stems of Plumbago zeylanica L. were cultured on MS medium with BA 1.0 mg/L and IAA (0.01-0.15 mg/L) or NAA (0.1-0.15 mg/L). After 8-week cultured, stems were transferred to MS medium with extracted from stems of Portulaca grandiflora Hook (2-10 ml/L) or extracted from stems of Ipomoea batatas (L.) Poir. The results showed that, the appropriate medium for shoot formation was in MS with BA and IAA 0.1 mg/L or NAA 0.1 mg/L. The adventitious roots in vitro were formatted in MS medium supplied with extracted from stems Portulaca grandiflora Hook or from stems of Ipomoea batatas (L.) Poir 6 ml/L. Simultaneously, after 8-week cultured, the adventitious roots were collected and plumbagin qualitative were analyzed with pure plumbagin of Sigma. As the results, plumbagin presents in adventitious roots cultured.

Antagonism of Pseudomonas fluorescens from plant roots to Rigidoporus lignosus pathogen of rubber white roots in vitro

Damiri N, Mulawarman, Effendi RS. 2019. Antagonism of Pseudomonas fluorescens from plant roots to Rigidoporus lignosus pathogen of rubber white roots in vitro. Biodiversitas 20: 1549-1554. Indonesia's rubber productivity is still relatively low. This low productivity of rubber can be caused by many factors such as the attack of Rigidoporus lignosus. This study aims to explore antagonistic bacteria from the plant roots and test their antagonism ability to R. lignosus at the laboratory level. This research was conducted at the Laboratory at the Faculty of Agriculture, Sriwijaya University, Indralaya Ogan Ilir District, South Sumatra, Indonesia. Corporate and bacterial isolations are carried out by serial dilution method. In-vitro testing of antagonistic bacteria was carried out using the dual-culture technique method on sterile PDA media by direct opposition between R. lignosus culture and antagonistic bacteria explored. Results of the study showed that a number of bacterial isolates existed there, namely 11 bacterial isolates belonging to Pseudomonas fluorescens, four from turmeric roots, three from the roots of rubber seedlings, two from galangal roots and two from the roots of yielding rubber plants. P. fluorescens from roots of turmeric, rubber seedlings, rubber, and galangal was able and had the potential to be developed as biopesticide to control R. lignosus. The best isolate in suppressing the growth and development of R. ligonosus is P. fluorescens isolates from the roots of turmeric and those of rubber seedlings (isolates of C, B, and G).

Culture medium and inoculation methodology for the study of soft root rot caused by Phytopythium sp.

ABSTRACT: Cassava (Manihot esculenta Crantz) is an important crop in Brazil and Pará is the major producer of roots. High temperature and humidity of tropical regions favor the development of various diseases, among them the cassava root rot. The objective of this study was to evaluate the effect of luminosity and culture medium on the mycelial growth and sporulation of Phytopythium sp. associated with different methods of inoculation on cassava roots. In vitro tests for pathogen growth were established in a 2 x 6 factorial design (luminosity x culture medium) with five replicates and the means were compared by t test (P≤0.05). The culture medium containing sweet cassava root produced greater mycelial development and higher pathogen sporulation and it was the most suitable medium for pathogen culture. The culture under absence of light generated better mycelial growth than culture under 12 hour of light. Regarding the type of inoculation, the response was better when deeper injuries were induced.

Conventional and In Vitro Propagation of Lechenaultia macrantha (Goodeniaceae)

Lechenaultia macrantha K. Krause (Goodeniaceae) is a species with great horticultural potential that is endemic to the sandy and gravelly soils of central, southwestern Australia. The effectiveness of several conventional and in vitro propagation techniques were assessed. Seeds possessed non-deep physiological dormancy, and a combination of seed nicking and imbibition in 10% (v/v) smoke water for 24 hours resulted in 81% germination after 33 days of incubation. Softwood stem cuttings produced adventitious roots readily without the need for exogenous auxin application. In vitro microcuttings produced shoots in response to cytokinins. However, optimal or suboptimal cytokinin concentrations resulted in hyperhydric shoots, which poses an obstacle to successful micropropagation. The use of auxin was necessary for the initiation of adventitious roots in vitro. This information will assist in the horticultural development of this species.