Acclimatization of Sweet Potatoes Under in vitro Application of Diatomaceous Earth.

Diatomaceous earth is an organic naturally occurring material rich in silicon. This silicon source can be used in organic agriculture, it also has a great potential of use in the acclimatization of crops. However, there are no reports of the effects of diatomaceous earth supplementation on the micropropagation of sweet potato. Thus, the objective of this study was to evaluate the effects of different concentrations of diatomaceous earth applied in vitro on the growth, physiology and anatomy of sweet potato cv. 'Brazlândia Branca' after acclimatization. Four concentrations of diatomaceous earth. After 30 days of in vitro growth, the plants were transferred to a greenhouse for acclimatization. After 45 days, leaf number, shoot and root length, fresh and dry shoot and root mass, gas exchange, chlorophyll content, root and leaf anatomy. The experimental design was completely randomized. The supplementation of diatomaceous earth in the in vitro cultivation had beneficial effects, increasing the accumulation of mass, improving the photosynthetic apparatus and promoting favorable anatomical characteristics during the acclimatization of the sweet potato plants. In addition, the use of diatomaceous earth achieved adequate seedling development, with higher seedling quality and resistance to biotic and abiotic effects than attained with control treatment.

Endophytic bacteria from strawberry plants control gray mold in fruits via production of antifungal compounds against Botrytis cinerea L.

Botrytis cinerea causes the gray mold disease in a wide range of plant hosts, especially in post-harvest periods. The control of this phytopathogen has been accomplished through the application of fungicides. However, this practice can cause environmental problems and increase fruit production costs. In addition, this fungus species has developed resistance to conventional synthetic fungicides. In this context, plant growth-promoting bacteria have shown potential for application in agricultural production because they are able to stimulate plant growth through different mechanisms, including the biological control of phytopathogens (indirect growth promotion mechanism). The aim of this work was to evaluate in vitro and in fruits the potential for indirect plant growth-promotion of bacteria isolated from strawberry leaves and roots. Dual plate method and inverted plate method were used to verify the ability of controlling in vitro the growth of Botrytis cinerea via the production of diffusible and volatile antifungal compounds, respectively. The effect of six bacterial isolates that showed greater potential for biological control in vitro was evaluated by scanning electron microscopy. Antifungal compounds produced by these bacterial isolates were identified by liquid chromatography coupled with mass spectrometry. Six bacterial strains were tested on strawberry pseudofruits. Five selected strains belong to the genus Bacillus and one to the genus Pantoea sp. Selected strains were able to inhibit more than 80 % of the mycelial growth of B. cinerea by the production of diffusible compounds and 90 % by volatile antifungal compounds production. Scanning electron microscopy showed the intense degradation of fungal hyphae caused by the presence of all bacterial strains. Bioactive compounds (salycilamide, maculosin, herniarin, lauroyl diethanolamide, baptifoline, undecanedioic acid, botrydial, 8 3-butylidene-7-hydroxyphthalide and N-(3-oxo-henoyl)-homoserine lactone) were obtained from liquid culture of these strains and extraction with ethyl acetate. All six isolates tested in vivo reduced the incidence of gray mold in strawberry pseudofruits in postharvest. It is concluded that isolates 26, 29, 65, 69, 132 (Bacillus sp.) and MQT16M1 (Pantoea sp.) have potential application for the biological control of Botrytis cinerea in strawberry via the production of diffusible and volatile antifungal compounds.

Challenges of organic agriculture for the production of composts and vermicompost for the production of medicinal plants: a socioeconomic demand / Desafios da agricultura orgânica na produção de composto e vermicomposto na produção de plantas medicinais: uma demanda socioeconômica

Although the demand for organic fertilizers in agriculture is growing, it remains incipient in some production sectors, such as medicinal plant production, which does not possess specific technology for its development. Solid residues are highly contaminant to water sources, soil, populations and biodiversity but can potentially be used to produce organic composts and vermicompost, such production not only enables nutrient recycling but also acts on soil conditioning, increasing soil organic matter and improving its physical, chemical and biological characteristics, as well as strengthening organic production with an emphasis on medicinal plant production. In this context, recommendations for and applications of organic fertilizers available in the market were reviewed; in addition, the imminent socioeconomic demand for organic compost and vermicompost production was contextualized based on residues from coffee and sugarcane production and cattle farming for application to the medicinal plant production chain. It is concluded that although these sectors produce a considerable amount of residues, they are not being reused in formulation of organic composts and vermicompost, and commercial organic fertilizers recommended for medicinal plant production were not found. Thus, the formulation of vermicomposting and composting from the reuse of agricultural residues, are potential social, economic technologies and tools to be valued and disseminated to traditional and family farmers. (AU)

Embora a demanda por fertilizantes orgânicos na agricultura seja crescente, ela ainda é incipiente em alguns setores produtivos, como a produção de plantas medicinais, que não possui tecnologia específica para seu desenvolvimento. Os resíduos sólidos são altamente contaminantes para fontes de água, solo, populações e biodiversidade, mas podem ser potencialmente utilizados para a produção de compostos orgânicos e vermicomposto, tal produção não só possibilita a reciclagem de nutrientes, mas também atua no condicionamento do solo, aumentando a matéria orgânica do solo e melhorando seu aspecto físico, químico e características biológicas, além do fortalecimento da produção orgânica com ênfase na produção de plantas medicinais. Nesse contexto, foram revisadas as recomendações e aplicações dos fertilizantes orgânicos disponíveis no mercado; além disso, a iminente demanda socioeconômica pela produção de composto orgânico e vermicomposto foi contextualizada a partir dos resíduos da produção de café, cana-de-açúcar e pecuária para aplicação na cadeia produtiva de plantas medicinais. Conclui-se que embora esses setores produzam uma quantidade considerável de resíduos, eles não estão sendo reaproveitados na formulação de compostos orgânicos e vermicomposto, e não foram encontrados fertilizantes orgânicos comerciais recomendados para a produção de plantas medicinais. Sendo assim, a formulação de vermicompostagem e compostagem a partir do reaproveitamento de resíduos agropecuários, são potenciais tecnologias sociais, econômicas e ferramentas a serem valorizadas e disseminadas para os agricultores tradicionais e familiares. (AU)

Endophytic bacteria of garlic roots promote growth of micropropagated meristems.

Garlic (Allium sativum L.) is one of the crops whose economic importance has increased considerably in recent years in Brazil. The use of plant growth-promoting bacteria (PGPB) is a useful alternative for reducing the cost of agricultural inputs and, consequently, for increasing productivity. Therefore, the main objective of this work was to isolate and evaluate potential growth promoters in plants and plant pathogenic fungi growth inhibitors using endophytic bacteria from garlic roots and bacteria from the Agricultural Microbiology Culture Collection at the Federal University of Lavras. Besides verifying improvements in the growth and physiology of garlic meristems grown in vitro under the action of PGPB. Forty-eight endophytic bacteria were identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry based on the protein profile of each isolate. Four isolates were chosen according to their ability to fix nitrogen, to produce auxin and solubilize phosphate. The cultivation of garlic meristems in tissue culture with these bacteria was established at a population level of 106 CFU/mL. The evaluated criteria were: (1) the colonization capacity of the bacteria inside the garlic plants determined through scanning electron microscopy; (2) the chlorophyll content; and (3) the growth of garlic plants in vitro post-PGPB inoculation. Volatiles emitted by those isolates inhibited fungi growth. The inoculation of garlic meristems with Enterobacter cloacae and Burkholderia cepacia promoted an improvement in the growth and physiological attributes of garlic, indicating the feasibility of their application as plant growth promoters for commercial cultivation.

Polyploidy induction in Physalis alkekengi / Indução de poliploidia em Physalis alkekengi

Physalis alkekengi is an ornamental plant that can also be used as a medicinal plant due to its anti-inflammatory, bactericidal, antitumor and fungicidal properties. Polyploidization can be an important tool in the genetic improvement of this species. The objective this work was to obtain tetraploids in vitro and to evaluate the phytotechnical traits of P. alkekengi. For this, nodal segments of P. alkekengi var. Franchettii were inoculated into petri dishes containing 100 ml of MS medium supplemented with colchicine at concentrations 0; 0.04; 0.08; 0.12; and 0.16% and kept in the dark for 24 and 48h. After the respective treatment periods with colchicine the segments were inoculated into test tubes. The tetraploids were identified by flow cytometry and classical cytogenetics. In vitro seedlings were measured: root length, nodal segment length, leaflet number and total leaf area. In the acclimatization phase, the area of the second leaf and total leaf, petiole radius, stem length, fruit weight with calyx, without calyx, fruit diameter, number of seeds and brix of the pulp were evaluated. Chlorophyll a, chlorophyll b, total chlorophyll, total carotenoid, total chlorophyll / total carotenoid ratio and chlorophyll a / b ratio were also estimated. The treatment that most produced tetraploid seedlings was with 0.08% colchicine per 24h. No significant difference was observed in 7 (seven) variables, these being all variables of photopigments, stem diameter (steam) and brix. In general, diploid (2x) plants were better in 9 (nine) while tetraploid seedlings were better in 6 (six) of the phytotechnical variables. It was concluded that the MS medium supplemented with 0.08% colchicine for 24 h allowed P. alkekengi tetraploides to be obtained with better phytotechnical qualities.

Physalis alkekengi é uma planta ornamental que também pode ser usada como planta medicinal devido às suas propriedades anti-inflamatórias, bactericidas, antitumorais e fungicidas. A poliploidização pode ser uma ferramenta importante para o melhoramento genético dessa espécie. O objetivo deste trabalho foi obter tetraplóides in vitro e avaliar as características fitotécnicas de P. alkekengi. Para isso, segmentos nodais de P. alkekengi var. Franchettii foram inoculados em placas de Petri contendo 100 ml de meio MS suplementado com colchicina nas concentrações 0; 0,04; 0,08; 0,12; e 0,16% e mantido no escuro por 24 e 48h. Após os respectivos períodos de tratamento com colchicina, os segmentos foram inoculados em tubos de ensaio. Os tetraplóides foram identificados por citometria de fluxo e citogenética clássica. As plântulas in vitro foram medidas: comprimento da raiz, comprimento do segmento nodal, número de folhetos e área foliar total. Na fase de aclimatação foram avaliadas a área da segunda folha e área foliar total, raio do pecíolo, comprimento do caule, peso do fruto com cálice, sem cálice, diâmetro do fruto, número de sementes e brix da polpa. Também foram estimadas clorofila a, clorofila b, clorofila total, carotenóides totais, razão clorofila total / carotenóide total e razão clorofila a / b. O tratamento que mais produziu mudas tetraplóides foi com colchicina a 0,08% por 24 horas. Não foi observada diferença significativa em 7 (sete) variáveis, sendo todas variáveis de fotopigmentos, diâmetro do caule (vapor) e brix. Em geral, as plantas diplóides (2x) foram melhores em 9 (nove) variáveis fitotécnicas, enquanto as mudas tetraplóides foram melhores em 6 (seis). Concluiu-se que o meio MS suplementado com colchicina a 0,08% por 24 h permitiu obter tetraploides de P. alkekengi com melhores qualidades fitotécnicas.

Beneficial effects of inoculation of growth-promoting bacteria in strawberry.

Plant growth-promoting bacteria have been highlighted by their potential for application in plant production, allowing the reduction of the use of fertilizers and pesticides, which is due to the ability to stimulate the growth of plants by nitrogen-fixation and production of phytohormones, such as indole-3-acetic acid (IAA). The objective of this study was to verify the potential of plant growth promotion of 25 wild isolates from the Agricultural Microbiology Culture Collection of the Federal University of Lavras (CCMA-UFLA) through the evaluation of the biological nitrogen-fixation capacity and the production of IAA. In addition, the growth of three selected strains inoculated on roots of strawberry seedlings in greenhouse conditions was evaluated. The experiment was conducted in a completely randomized design (CRD), with an 8 × 2 factorial schemes involving eight combinations of bacteria: alone, in pairs and threes, plus the control without inoculation. Two fertilizer levels were used (0% and 50% of nitrogen), totaling 16 treatments with eight replicates each. After 75 days, variables such as root length, root dry weight, aerial part length, aerial part dry weight, leaf number, total dry mass and ultrastructural analysis of the inoculated and uninoculated roots, were evaluated. The results showed that the strawberry crop responded positively to inoculation with the three bacteria combined Azospirillum brasilense (Ab-V5) + Burkholderia cepacia (CCMA 0056) + Enterobacter cloacae (CCMA 1285) compared to the uninoculated controls. More expressive responses in terms of plant growth were observed in relation to the combined inoculation of the three bacterial strains plus fertilizer application with 50% of nitrogen.

Simulating stress condition through compaction in banana plant cultivated In vitro / Mulação de estresse por compactação em bananeiras cultivadas In vitro

Banana cultivation is an agricultural activity practiced in different regions and constantly subjected to abiotic stresses that limit its productivity. To treat the effect of these stresses research can be undertake by simulating them in vitro since it limit the effect of the external factor in the experiment. Therefore, the objective of this study was to simulate the compaction in banana plant cultivated in vitro using Phytagel. To realize the experiment, we used MS culture medium with two distinct consistency added in the testing tubes. In the bottom part was added 10 mL of culture medium with consistency of jellification: 1.8, 2.8, 3.8, 4.8 and 5.8 g L-1 of Phytagel. Over this culture medium was added 5mL of half MS with consistency standard 1.8 g L-1 of Phytagel. Posteriorly, the planting materials from cultivar Grand Naine, BRS Vitória and BRS Princesa were inoculated in the growth medium. After 30 days of culture the plant materials were submitted for agronomic and physiological evaluation. The result showed non-significant difference among the compaction factors on physiological parameters however variety Grand Naine presents better performance in this character. Besides variety Grand Naine increased the rate of photosynthesis under compaction. This behaviour probably occurred due to overcoming the effect of stress by the variety. Therefore, it can be concluded that the cultivar Grand Naine is superior to cultivars BRS Vitória and BRS Princesa since it produces superior performance on rate of photosynthesis, stomatal conductance, and transpiration under simulated compaction conditions that favor the accumulation of plant biomass.

A bananicultura é uma atividade agrícola difundida em diferentes áreas e constantemente sujeita a estresses abióticos, os quais limitam sua produtividade. Para sanar o efeito dos estresses abióticos pesquisas podem ser simuladas in vitro, pois devido à característica de ambiente controlado pode proporcionar efeito puro do fator de estresse. Sendo assim, o objetivo do presente trabalho foi simular a compactação em bananeiras cultivadas in vitro mediante o uso de Phytagel. Para instalação do experimento utilizou-se o meio de cultura MS em duas consistências distintas, adicionadas a tubos de ensaios. Na parte inferior desses, adicionou-se 10 mL do meio de cultura com distintas consistências de geleificação: 1,8; 2,8; 3,8; 4,8 e 5,8 g L-1 de Phytagel. Sobre este meio de cultura foi adicionado mais 5 mL de meio MS, mas na consistência padrão de 1,8 g L-1 de Phytagel. Posteriormente foram inoculados propágulos das cultivares Grand Naine, BRS Vitória e BRS Princesa. Aos 30 dias de cultivo o material vegetal foi submetido a avaliações fitotécnicas e fisiológicas. Observa-se que as variáveis fitotécnicas não foram significativas para o fator compactação e que a cultivar Grand Naine obteve maior desempenho nessa característica. Observa-se também que a cultivar Grand Naine aumenta sua taxa fotossintética mediante a compactação. Esse comportamento provavelmente ocorre visando a superação desse estresse e explica porque as variáveis fitotecnicas não são comprometidas. Portanto, conclui-se que a cultivar Grand Naine é superior as cultivares BRS Vitória e BRS Princesa, porque mediante a simulação de compactação apresenta superioridade em taxa fotossintética, condutância estomática e transpiração, favorecendo o acumulo de biomassa vegetal.