The arbuscular mycorrhizal fungi colonizing the roots of pre-nursery stage of oil palm seedlings: Elaeis guineensis in Malaysia

Aims@#Arbuscular mycorrhizal is an obligate mutualistic symbiosis fungus which survives by forming endomycorrhizal on plant roots. The arbuscular mycorrhizal fungi are not host-specific, allowing them to form a mutualistic symbiosis with a wide range of host plants including oil palm. In Malaysia, the arbuscular mycorrhizal fungi are used as a growth enhancer for the oil palm: Elaeis guineensis. The arbuscular mycorrhizal fungi are introduced only during transplantation to the field when the ages of the seedlings are approximately one year old. As such, this study is designed to investigate the ability of the arbuscular mycorrhizal fungi to form colonisation with pre-nursery oil palm seedlings. @*Methodology and results@#Here, the arbuscular mycorrhizal fungi were introduced at the pre-nursery stage oil palm seedlings. After inoculation, the seedlings were harvested on different days, i.e. on day-3, day-7, day-14, day-21, day-40 and day-60 to determine the colonisation of arbuscular mycorrhizal fungi. We found that the arbuscular mycorrhizal fungi are able to form a mycorrhizal association with the oil palm seedling at the pre-nursery stage after 40 days of inoculation, and the arbuscular mycorrhizal fungi that formed the association are Glomus sp. and Scutellospora sp. @*Conclusion, significance and impact of study@#This study suggested that the oil palm seedling can be made into a mycorrhizal plant as early as the nursery stage before transplanting them into the plantation.

Crescimento de mudas de peroba rosa em resposta à inoculação com fungos micorrízicos arbusculares / Growth responses of peroba rosa seedlings due to arbuscular mycorrhizal fungi inoculation

O objetivo neste trabalho foi de avaliar o efeito da inoculação de fungos micorrízicos arbusculares no crescimento de mudas de peroba rosa (Aspidosperma polyneuron). O experimento foi conduzido em delineamento experimental, inteiramente casualizado, em casa de vegetação com seis repetições. Utilizou-se mistura de solo e areia (3:1), desinfestado como substrato, com os seguintes tratamentos de inoculação: Gigaspora margarita, Glomus clarum, Scutellospora heterogama, Acaulospora scrobiculata e uma mistura de fungos micorrízicos arbusculares (FMA). Após 120 dias, observou-se que a colonização micorrízica radicular foi de 28,3 por cento a 48,4 por cento para a mistura de FMA e para G. margarita, respectivamente. As plantas inoculadas com G. margarita e G. clarum apresentaram maior crescimento, indicando o potencial da inoculação desses fungos na produção de mudas.

The aim of this study was to examine the effects of arbuscular mycorrhizal fungi (AMF) inoculation on Aspidosperma polyneuron seedlings growth. The experiment was conducted under greenhouse conditions in a randomized design using a disinfected mixture of soil + sand (3:1) with the following treatments: Gigaspora margarita, Glomus clarum, Scutellospora heterogama, Acaulospora scrobiculata, a mixture of arbuscular mycorrhizae fungi (AMF) and a non-inoculated control with six replicates. After 120 days of seed germination, it was observed that root colonization was from 28.3 percent to 48.4 percent for mixture of AMF and G. margarita, respectively. The plants inoculated with G. margarita or G. clarum showed higher growth than other treatments, which evidence the potential of AMF inoculation in seedlings production.

Indolacetic acid production by P-solubilizing microorganisms and interaction with arbuscular mycorrhizal fungi - DOI: 10.4025/actascibiolsci.v29i3.492 / Produção de ácido indol acético por microorganismos solubilizadores de fosfato e sua interação com fungos micorrízicos arbusculares - DOI: 10.4025/actascibiolsci.v29i3.492

Indolacetic acid (IAA) production was evaluated under in vitro conditions by five P-solubilizing fungi (PSF), identified as Aspergillus sp. and four P-solubilizing bacteria (PSB) of the Enterobacteriaceae family. The bacteria and fungus isolates were incubated in a liquid medium at 28ºC for two and four days, respectively. Moreover, two PSB isolates of the Enterobacteriaceae family (PSB 8 and PSB 56) were evaluated in relation to their ability to stimulate or inhibit spore germination and hyphal growth of two arbuscular mycorrhizal fungi (AMF) species under in vitro conditions. Two assays were carried out in Petri dishes with agar (0.8%), the first using the AMF Gigaspora margarita and the second with the AMF Scutellospora sp. The treatments were: inoculation of PSB 8; PSB 56 and uninoculated control. P-solubilizing isolates produced different amounts of IAA and most PSF isolates produced higher IAA than PSB. From the 18th day of incubation of Scutellospora sp., a significant increase in hyphal growth in the treatment inoculated with PSB 8 was observed. In contrast, PSB 56 inhibited the hyphal growth of Gigaspora margarita from the 24th day of incubation.

Avaliou-se o potencial de produção de ácido indol acético (AIA) in vitro por cinco isolados de fungo solubilizador de fosfato (FSF) do gênero Aspergillus sp. e quatro isolados de bactéria solubilizadora de fosfato (BSF) da família Enterobacteriaceae. Os isolados de bactéria e fungo foram incubados em meio líquido a 28ºC, por dois e quatro dias, respectivamente. Além disso, dois isolados de BSF da família Enterobacteriaceae (BSF 8 e BSF 56) foram avaliados quanto à capacidade de estimular ou inibir a germinação de esporos e o desenvolvimento micelial de duas espécies de fungos micorrízicos arbusculares (FMAs) in vitro. Foram instalados dois ensaios em placas de Petri, contendo agar-água (0,8%); um, utilizando o FMA Gigaspora margarita e o outro, com o FMA Scutellospora sp. Os tratamentos foram inoculação de BSF 8; BSF 56 e controle não-inoculado com BSF. Houve uma produção diferenciada de AIA pelos solubilizadores, destacando-se a maior produção pela maioria dos isolados fúngicos. A partir do 18º dia de incubação de Scutellospora sp., foi verificado um incremento significativo do comprimento de hifas no tratamento inoculado com BSF 8. Contrariamente, o crescimento micelial de G. margarita foi inibido pelo isolado BSF 56, a partir do 24º dia de incubação.

Effects of Interspecific Interactions of Arbuscular Mycorrhizal Fungi on Growth of Soybean and Corn

Growth responses of Zea mays and Glycine max to colonization by mixture of combination of three species of arbuscular mycorrhizal (AM) fungi, two species of Glomus and a species of Scutellospora were compared. In Zea mays, plants inoculated with single species of AM fungi showed significantly higher in dry weight than non-mycorrhizal plant for all three AM fungal species. Also, growth of plants inoculated with spores of two species of AM fungi was significantly higher than nonmycorrhizal control except for plants inoculated with two Glomus species. When three species of AM fungi were inoculated, the plants showed the highest growth. In Glycine max, plants with single AM fungal species inoculation were not significantly different in plant growth from nonmycorrhizal plants. When the plants were inoculated with combination of two or more AM fungal species, their growth significantly increased compared to nonmycorrhizal plants. In both plant species, mycorrhizal root colonization by Scutellospora species was significantly lower than by Glomus species.