Improvement of Provitamin A in Maize Varieties Using Arbuscular Mycorrhizal Fungus, Glomus clarum

Arbuscular mycorrhizal fungus (AMF, Glomus clarum) has been used widely as a bio-amendment and bio-control agent in several biotechnological studies. In this study, biofortification of maize with provitamin A using AMF was investigated. Five maize varieties (V1 = white drought-resistant maize, V2= yellow provitamin A maize, V3= white drought-tolerant maize, V4= yellow striga-resistant maize and V5= white striga-resistant maize) were evaluated in a screen house experiment laid out in a completely randomized design with three treatments: T1 = maize + AMF before planting, T2 = maize + AMF, inoculated two weeks after planting and T3 (control) = maize only, and four replications. The result showed that AMF significantly (p<0.05, p = 0.0029) increased the provitamin A level of the maize varieties. White drought-tolerant maize (V3) had the highest provitamin A content (581.57 µg) after harvest, while the least (288.33 µg) was found in white drought-resistant maize (V1). Also, the effect of the treatments on the growth traits (plant height, leaf length, number of leaves per plant) of the maize varieties was highly significant. Therefore, AMF could be considered in breeding maize with high provitamin A content and improved morphological characters.

Mitigating Impact of Soil Salinization on Growth, Yield and Fruit Nutritional Quality of Abelmoschus esculentus L. (Okra) Using Arbuscular Mycorrhiza Fungus ()

Soil salinity is a severe environmental stress that limits crop growth and productivity. Mycorrhizal fungi association has the potential to minimize environmental stress like soil salinization in some plant species. Hence, an experiment was conducted to examine the potential of an Arbuscular mycorrhiza (AM), Glomus clarum, to reduce salt stress in Abelmoschus esculentus L. (okra). Seedlings of A. esculentus were raised in perforatedplastic pots filled with 3 kg top soil; treated with 0 (control), 35, 70, 140, 280 or 560 mM NaCl solution; and grouped into two. Each pot in the first group was inoculated with 20 g of AM spawn while pots in the second group were not inoculated with the mycorrhizal fungus. The experiment was laid out in a completely randomized design with each treatment replicated 5 times. Growth parameters in plants without AM including plant height, stem girth, leaf area and number of leaves decreased significantly with increasing salt concentration compared to the control. Salinity also reduced the growth parameters in plants with AM but did not differ significantly from the control. Fresh and dry weight of plant parts, total biomass, number of fruits, fruit fresh and dry weights as well as leaf total chlorophyll were reduced by salinity, but significant differences were recorded only in plants without inoculation with AM. Salinity with or without AM did not significantly affect fruit nutritional and proximate composition of A. esculentusnexcept Na+ that increased with increasing soil salinity. Inoculation of saline sites with arbuscular mycorrhizal fungus, Glomus clarum, could serve as a sustainable and environmentally safe treatment to enhance salinity tolerance in okra for improved productivity. Keywords: Salt stress, arbuscular mycorrhiza, okra, productivity

Doses de fósforo e fungos micorrízicos arbusculares no crescimento e produção do feijão-caupi em Roraim

Doses de fósforo e fungos micorrízicos arbusculares no crescimento e produção do feijão-caupi em Roraima. O feijão caupi é uma leguminosa cultivada por pequenos produtores, representando importante fonte de renda e ocupação no meio rural de Roraima. O objetivo do estudo foi avaliar o efeito da inoculação dos fungos micorrízicos arbusculares (FMAs) na cultura do feijão caupi em diferentes doses de fósforo. O experimento foi conduzido em casa de vegetação, em vasos, contendo, como substrato, Plintossolo Háplico distrófico. O experimento foi conduzido em esquema fatorial 3 x 5 (Glomus clarum, Scutellospora heterogama e sem inoculação) e cinco doses de P (0, 50, 100, 200, e 400 mg.dm-3) com uso do delineamento inteiramente casualisado (DIC), com seis repetições, sendo uma planta por vaso, o que totalizou 90 parcelas experimentais. Das 6 repetições, três foram conduzidas até estádio de florescimento e as outras três até a produção. As avaliações do experimento ocorreram em 86 dias após sua instalação. Foram analisados no estádio do florescimento a altura, número de folhas, matéria fresca da parte aérea, matéria seca da parte aérea, matéria seca de raiz, número de nódulos e matéria seca de nódulos e na produção o número de vagens.planta-1e número de -1 grãos.planta . Os tratamentos com Scutellospora heterogama e Glomus clarum apresentou os maiores valores para todas as variáveis analisados comparados ao tratamento sem inoculação. O feijão-caupi foi responsivo à aplicação de fosfato e inoculação de FMAs o que possibilita a redução da dose de fosfato utilizado pelo agricultor.

ARBUSCULAR MYCORRHIZAL FUNGI IN SEEDLING FORMATION OF BARBADOS CHERRY (Malpighia emarginata D.C.)

ABSTRACT The use of beneficial microorganisms such as arbuscular mycorrhizal fungi (AMF) may favor both the growth phase and the stabilization of the seedlings after transplantation. The aim of this study was to evaluate the effect of inoculation of different AMF species on the development of Barbados cherry seedlings from herbaceous and semi-hardwood cuttings. Softwood and semi-hardwood cuttings, previously rooted, were planted in 500 ml tubes filled with Plantmax® substrate and inoculated with three species of mycorrhizal fungi (Gigaspora margarita - Gimarg, Claroideoglomus etunicatum - Claetun and Glomus clarum - Glclar) isolated and combined (Gimarg + Claetun, Gimarg + Glclar, Claetun + Glclar and Gimarg + Claetun + Glclar). The statistical design was completely randomized in factorial scheme 2 x 8 (two types of cuttings and eight types of inoculation, including control without AMF inoculation) with ten replications. The seedlings were kept in a greenhouse for 100 days and height was measured every 15 days to determine the absolute and relative growth rate (AGR and RGR). At the end of the experiment the seedlings were sacrificed and determined height, fresh and dry shoot mass and root and mycorrhizal colonization rate. The results indicate potential for production of Malpighia emarginata D.C. seedlings inoculated with AMF with tendency to reduce the time for transplanting. The Gimarg + Claetun combination promoted higher rates of absolute growth and height of seedlings from herbaceous cuttings. The species Glomus clarum, isolated or associated with C. etunicatum, promoted higher colonization rates in herbaceous and semi-hardwood seedlings, respectively.

CO-INOCULATION OF GROWTH PROMOTING BACTERIA AND Glomus clarum IN MICROPROPAGATED CASSAVA PLANTS

ABSTRACT Arbuscular mycorrhizal fungi (AMF) and growth promoting bacteria in plants (PGPBs) benefit the survival and development of plantlets; such benefits are attributed to the increased absorption of nutrients, increased photosynthetic rate and tolerance to abiotic stress. The aim of this study was to evaluate if the co-inoculation PGPBs and the AMF, Glomus clarum, improves the growth of micropropagated Manihot esculenta Crantz. The experiment was conducted in the greenhouse. The PGPBs used were Azospirillum amazonense (BR 11140), Herbaspirillum seropedicae (BR 11175), Gluconacetobacter diazotrophicus (BR 11284) and Streptomyces sp. (S 30) and mixtures with double inoculation (Streptomyces sp + A. amazonense, Streptomyces sp + H. seropedicae, Streptomyces sp + G. diazotrophicus, A. amazonense + H. seropedicae, A. amazonense + G. diazotrophicus, and H. seropedicae + G. diazotrophicus). Strains of PGPBs inoculated in cassava cv. "BRA Pretinha III" influenced mycorrhizal colonization and the number of glomerospores, and synergistic effects occurred between Glomus clarum and PGPBs. The crude protein content revealed the contribution of PGPBs to nitrogen nutrition in cassava where the inoculated plants assimilated N in equal proportion with those that received mineral nitrogen. The combined inoculation of PGPBs in the presence of Glomus clarum was significant in cassava and fostered better performance in plant growth over time, similar to all the variables studied. Co-inoculation of PGPBs and AMF can meet the N need of cassava, with implications for the reduced use of N fertilizer.

RESPONSIVIDADE DE PLANTAS DE MILHO À INOCULAÇÃO COM FUNGOS MICORRÍZICOS ARBUSCULARES DA RIZOSFERA DE IPÊ AMARELO

Aumentar a produtividade do milho de uma forma sustentável é o desafio de todos os agricultores, objetivou-se isolar e selecionar fungos micorrizicos arbusculares (FMAs) nativos da rizosfera de ipê amarelo (Tabebuia serratifolia (Vahl) Nichols) e avaliar o efeito de sua inoculação em plantas de milho. A extração dos FMAs da rizosfera de ipê amarelo, o isolamento e a inoculação dos esporos em plantas de milho foram realizados no Laboratório de Fisiologia Vegetal e Crescimento de Plantas da Universidade Federal do Oeste do Pará (UFOPA) em outubro de 2017. O efeito da simbiose no crescimento inicial das plantas foi avaliado em condições de laboratório, sob iluminação artificial com fotoperíodo de 12 horas e regas diárias por 15 dias. Foram isolados 410 esporos de FMAs pertencentes a três espécies: Glomus clarum, G etunicatum e G. geosporum. Os FMAs colonizaram de forma eficiente o sistema radicular das plantas de milho e proporcionaram, na primeira coleta, incrementos superiores a 100% na massa seca da raiz e da parte aérea, quando comparadas às plantas controle. Conclui-se que a inoculação com os FMAs, nativos da rizosfera do ipê amarelo, aumenta a massa seca das plantas, tornando-se, um inoculante promissor para o cultivo do milho.PALAVRA CHAVE: Crescimento vegetativo, Micorrizas, Produtividade.