Search

Common Bean (Phaseolus vulgaris) is considered one of the most affordable sources to tackle hunger in underdeveloped countries. However, its cultivation takes place in regions that suffer from water deficiency, which limits plant growth and crop yield. Therefore, it is necessary to seek sustainable alternatives that mitigate the deleterious effects of water shortage. The aim of this study was to evaluate the potential for mitigating the effects of water deficit with the application of the microalgae Asterarcys quadricellulare (CCAP 294/1) in two bean cultivars (IAC 1850 and BRS ESTEIO). The plants were grown in pots, with foliar application of microalgae at stage of third fully expanded trefoil at concentrations of 0.5 mL L− 1 and 1.0 mL L− 1. The water deficit lasted for 7 days, and, after that, the rehydration of the plants was performed. Evaluations were carried out in three periods: i. on the third day after the start of water restriction, ii. one day after rehydration, iii. 10 days after rehydration. The levels of chlorophyll, sugars, protein and antioxidant enzymes were increased in plants treated with microalgae. At ten days after rehydration, there was an increase in leaf area, fresh mass, and leaf thickness in the treated plants. Our results demonstrate the effects of A. quadricellulare (CCAP 294/1) in mitigating the deleterious effects of water deficit, accelerating the recovery of the two common bean cultivars, which demonstrates its potential as a sustainable alternative to support food production under changing environment.

The use of natural bioactive sources to promote plant growth and crop yield gains, such as those obtained from algae, are in evidence as a sustainable agriculture practice. In this sense, recently the calcareous alga Lithothamnium sp. had its bioactive plant growth promoting effect related to the presence of high degree of humification humic acid with pronounced auxin-like effects, while the cyanobacterium Arthrospira platensis (Spirulina plantensis) has the plant growth promoting effect attributed to a pool of bioactive molecules, such as the free L-amino acids and polyamines. To explore the effect of algae sources combinations as plant biostimulants, the aim of this work was to evaluate the effects of foliar application of micronized Lithothamnium (Lm) associated with A. platensis (Ap) dried biomass in onion (Allium cepa) metabolism, growth and yield. For that, adopting an step by step approach three experiments were conducted: (i) foliar application to onion plants grown in pots in greenhouse comparing algae sources alone and combined, (ii) foliar application to onion plants in the field under organic system testing algae sources combinations (first season), and (iii) foliar application in the field comparing doses and frequencies of selected combinations (second season). The association of algae sources promoted growth and biochemical changes, thus pigment contents, total sugars, amino acids and nitrate reductase enzyme activity were improved, increasing the onion yield by two seasons in a nature friendly way.

In this study, Bacillus subtilis were applied on seeds, seedlings, and tomato crops for two years in an organic system. The product Serenade® was used on 'Cardyna' and 'Trinidade' cultivars with the objective of determining the effect of the bacteria on initial plant growth when applied to seeds (50 uL per seed) or the seedlings watered with 100 mL solution at 8 mL L-1 concentration, and tomato yield when applied at the concentration of 4 mL L-1 in the form of a soil drench, foliar sprays and their combination, considering their action in the promotion of growth and also in the induction of resistance allied to possible metabolic deviations. Seed application reduced initial plant growth, while seedling watering at transplanting promoted growth. Chlorophylls a, b and total chlorophyll, carotenoids, and the enzymes phenylalanine ammonia lyase, chitinase, and β1,3 glucanases were stimulated in a variable way among cultivars and applications, indicating the activation of plant defenses. Phenolic compounds, flavonoids, and total sugars were not altered, while the concentrations of reducing sugars were higher due to applications than those of non-reducing sugars. The metabolic changes did not influence the tomato yield.

The development of new natural biostimulant sources for a sustainable agriculture is a strategic issue aiming to improve the healthy food production. In this sense, the goal was to identify the biostimulant action of the calcareous alga Lithothamnium sp. (Rhodophyta) on onion in two experiments, (i) in pots and (ii) at field under organic system, both in factorial scheme with two onion cultivars and foliar sprays with micronized Lithothamnium sp. at concentration of 1.5 and 3.0 g L−1. The plant growth promotion and commercial yield improvement of two onion cultivars were achieved and related to changes on amino acid metabolism and source-to-sink flow stimuli. Better nutrient acquisition also was achieved related to the stimuli to thin roots growth, with N, Mg, Mn, Zn, and Cu content in bulbs improved at 3.0 g L−1, while 1.5 g L−1 allowed highest Ca, Mg, Mn, and Zn content in bulbs. Thus, the results presents Lithothamnium sp. as novel biostimulant source to grow onion, which effects related to the presence of bioactive humic acid that calcareous algae release by micronization.

This work is based on the hypothesis that the depositions of the calcareous alga Lithothamnium sp. at the bottom of the ocean contain bioactive humic substances which may promote plant growth. To achieve this, micronized Lithothamnium sp. powder was investigated in terms of the degree of humification using a colorimetric approach; the bioactivity in comparison with that of auxin IAA (3-indole acetic acid) using a bioassay with Vigna radiata and the effect of foliar sprays on organically grown tomatoes. Humification and formation of humic acid were identified to a high degree in micronized Lithothamnium sp., which was highly bioactive showing auxin hormone-like activity. When applied as foliar sprays, rooting, growth, and yield were improved and concentrations of amino acids, sugars, and protein of tomato plants increased. Thus, the results presented a novel use for Lithothamnium sp., whereby the calcareous algae depositions provided a highly active humic acid for use as a plant biostimulant.

The development of sustainable ways to increase crop productivity is essential to meet the growing demand for food. Microalgae are rich in bioactive molecules and can be produced on a large scale and at a low cost. Therefore, we hypothesized that the microalga Asterarcys quadricellulare (CCAP 294/1), a rich source of free L-amino acids, can increase the growth and yield of tomatoes. To determine the potential of A. quadricellulare, we performed a two-year study by applying A. quadricellulare biomass using a foliar spray on tomato plants. In the first season, weekly applications were performed during the full cycle of tomatoes. The effect of A. quadricellulare biomass of 0.05, 0.15, 0.25, and 0.40 g L-1 on tomato yield was determined through regression analysis. In the second season, the solution of 0.25 g L-1, which showed the best results, was tested on two tomato cultivars using a weekly and a biweekly frequency of application. Both cultivars were positively affected by the application of biomass, which promoted the increase in leaf area and yield, along with higher contents of sugar, free amino acid, and protein. Thus, we determined the role of A. quadricellulare as an effective biofertilizer in tomatoes.

Made available in DSpace on 2022-05-01T15:13:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 The use of single-bud sugarcane propagules brings a challenge concerning the initial sprouting, as the physiological ages of buds affect their outgrowth. This work is addressed to stimulate the sugarcane buds sprouting in a nature-friendly way using microalgae biomass. A metabolomics approach, connecting physiological and phenotypic changes, was adopted to identify the microalgae effect on sugarcane sprouting. For that, initially the changes in propagules metabolites according to their size and bud position in culm were determined. Then, single-bud propagules from apical, medial and basal segments of culms from cv. RB036152 were immersed in a solution containing microalgae biomass. Budding percentage, sprouts size and changes in sprouts and propagules metabolites—free amino acids; total soluble, reducing and non-reducing sugars; phenolic compounds; polyamines—putrescine, spermine, spermidine; tryptophan, 5-hydroxytryptamine (serotonin) and tryptamine—were determined. Data indicated that bud outgrowth is accompanied by the increase in its amino acids and non-reducing sugars accumulation at the early stages of budding. The propagules immersion in the suspension of green microalgae Asterarcys quadricellulare (CCAP 294/1) biomass improved bud sprouting percentage and promoted remarkable sprouts growth, increasing spermidine and reducing putrescine content in sprouts, thus indicating the polyamines as the key compounds of nitrogen metabolism related to sugarcane sprouting and sprouts growth, a pathway that was triggered by microalgae biomass. Departamento de Fitotecnia e Fitossanidade Universidade Federal do Paraná, Paraná Departamento de Química Instituto de Biociências Universidade Estadual Paulista Júlio de Mesquita Filho, São Paulo Departamento de Química Instituto de Biociências Universidade Estadual Paulista Júlio de Mesquita Filho, São Paulo

espanolRESUMEN El biofertilizante de la cana de azucar derivado de la fermentacion por la bacteria Corynebacterium glutamicum es un caldo que contiene aminoacido L-glutamico. Para evaluar el efecto biofertilizacion de este caldo en la produccion organica de las plantulas de col china (Brassica campestris var. Pekinensis), se realizo un experimento en un vivero de plantulas en la zona organica de la Universidad Federal de Parana (UFPR). Las soluciones acuosas del caldo fermentado se aplicaron a hojas en concentraciones de 0,2 mL L-1 y 0,8 mL L-1 ademas del control con aplicacion de agua. Los resultados indicaron que la aplicacion foliar promovio el desarrollo de la parte aerea y las raices y aumento la concentra cion de aminoacidos libres totales en las plantulas de col china. Estos resultados demuestran la accion biofertilizante del caldo bacteriano fermentado, promoviendo el crecimiento de las plantulas y estimulando la sintesis de aminoacidos, aumentando la concentracion de aminoacidos libres totales. EnglishABSTRACT The biofertilizer derived from the fermentation of sugarcane molasses by the bacterium Corynebacterium glutamicum is a broth containing L-glutamic amino acid. To evaluate the biofertilization effect of this broth on the organic production of Chinese cabbage seedlings (Brassica campestris var. Pekinensis), an experiment was performed in a seedling nursery in the organic area at the Federal University of Parana (UFPR). Aqueous solutions of the fermented broth were applied to leaves at concentrations of 0.2 mL L-1 and 0.8 mL L-1 in addition to the control with water application. The results indicated that foliar application promoted the development of the aerial part and roots and increased the concentration of total free amino acids in Chinese cabbage seedlings. These results demonstrated the biofertilizing action of the bacterial fermented broth, promoting seedling growth and stimulating amino acid synthesis, by increasing the concentration of total free amino acids.

The plant biostimulant activity of the green microalga Desmodesmus subspicatus was investigated, focusing on its potential application to organic crops. Different concentrations of D. subspicatus biomass suspensions were applied to tomato seedlings (Solanum lycopersicum) via a foliar spray. The treatments promoted root growth and foliar area, which increased when the suspension was applied at concentrations of 1 g L−1 and 0.4 g L−1, respectively. To elucidate the major constituents responsible for this potential activity, the biomass of D. subspicatus was submitted to aqueous extraction and dialysis (1 kDa cut-off), giving rise to the non-dialyzable fraction E (12.3%). Size-exclusion chromatography performed on fraction E using a Bio-Gel P-2 column yielded six subfractions. Gas chromatography-mass spectrometry (GC–MS) and nuclear magnetic resonance (NMR) analyses of the E subfractions revealed the presence of glycosides as major constituents (approx. 81%), including one acidic glycoside, [6-sulfo-α- D -quinovopyranosyl-(1→1)-glycerol], and two neutral galactosyl glycosides, [α- D -galactopyranosyl-(1→6)-β- D -galactopyranosyl-(1→1)-glycerol] and [β- D -galactopyranosyl-(1→1)-glycerol]. Ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) analyses of fraction E resulted in the identification of the phytohormone zeatin (35 μg g−1). To evaluate the biostimulant potential of fraction E, different concentrations (0.5, 1.0, 1.5, and 2.0 g L−1) were tested for their effects on tomato seed germination, hypocotyl volume, and length. All tested concentrations induced increased hypocotyl lengths and volumes compared with standard treatment (water), at rates equivalent to those in response to a commercial product derived from Ascophyllum nodosum brown seaweed. These results indicated that the biomass suspension and aqueous extract of D. subspicatus showed plant growth biostimulant activity. Glycosides, together with zeatin, may play important roles in biostimulant activity.

In order to increase the understanding about Arthrospira platensis biomass use to plant growth promotion, the aim of this study was to determine total free amino acid content on lyophilized biomass and the biomass bioactivity on bioassay, as well as, the effects of foliar applications of aqueous suspension of biomass on seedlings growth ascertaining biochemical variables related to the potential bioactivity, and also at field on organically grown red beet yield. The results identified the bioactivity and expressed well the capacity of plant growth promotion related to stimulus on chlorophyll synthesis and on amino acid and protein increments on seedlings leaves. The yield had significant improvement related to hypocotyl growth. The results could be justified by the content of free amino acids on biomass, being them the highest amount of potential bioactive compounds of cyanobacteria. The Arthrospira platensis lyophilized biomass could be considered an efficient biofertilizer-biostimulant source, promoting yield gains by a sustainable way.

Biofortification can be understood as a strategy to raise nutrients levels in vegetables edible structures, which can positively interfere in human diet. Biofertilizers are an interesting option in alternative production systems, as they can increase food nutritional quality and contribute to plant development, while aiding environment sustainability as natural products. The use of microalgae and humic acid as biofertilizers points to improvements in nutrients and biomolecules content in plants, however, their combined application is still unexplored. In that scenario, it was carried a study with onions about the influence of applications via root immersion in microalgae Scenedesmus subspicatus (Sc) and humic acid (HA) solutions, analyzing possible alterations of macro and micronutrients, total sugars, reducing sugar, free total amino acids, , total soluble solids, soluble proteins and antioxidant capacity in the bulbs. Treatments consisted of one minute seedlings roots immersion from two onion cultivars in solutions containing microalgae and humic acid, and then transplanted to organic system field. There were used three concentrations: control, 0.3 g L-1 Sc + 0.3 g L-1 HA (3SH) and 0.6 g L-1 Sc + 0.6 g L-1 HA (6SH). Results show that the treatments with microalgae with humic acid association were able to increase the content of N, carbohydrates and soluble proteins, also elevating antioxidant activity in onion bulbs. La biofortificación puede entenderse como una estrategia para aumentar los niveles de nutrientes en las estructuras comestibles de los vegetales, lo que puede interferir positivamente en la dieta humana. Los biofertilizantes son una opción interesante en los sistemas de producción alternativos, ya que pueden incrementar la calidad nutricional de los alimentos y contribuir al desarrollo de las plantas, al mismo tiempo que ayudan a mantener el medio ambiente como productos naturales. El uso de microalgas y ácido húmico como biofertilizantes apunta a mejoras en el contenido de nutrientes y biomoléculas en las plantas, pero su aplicación conjunta aún no se ha explorado. En este escenario, se realizó un estudio con cebollas sobre la influencia de aplicaciones vía inmersión radicular en soluciones de microalgas Scenedesmus subspicatus (Sc) y ácido húmico (HA), analizando posibles cambios en macro y micronutrientes, azúcares totales, azúcares reductores, sólidos solubles totales, aminoácidos libres totales, proteínas solubles y capacidad antioxidante en bulbos. Los tratamientos consistieron en sumergir las raíces de plántulas de dos cultivares de cebolla en soluciones que contenían microalgas y ácido húmico durante un minuto, y luego trasplantarlas al campo del sistema orgánico. Se utilizaron tres concentraciones: control, 0,3 g L-1 Sc + 0,3 g L-1 HA (3SH) y 0,6 g L-1 Sc + 0,6 g L-1 HA (6SH). Los resultados muestran que los tratamientos con microalgas con asociación de ácidos húmicos fueron capaces de incrementar el contenido de N, carbohidratos y proteínas solubles, aumentando también la actividad antioxidante en bulbos de cebolla. A biofortificação pode ser entendida como uma estratégia para elevar os níveis de nutrientes nas estruturas comestíveis dos vegetais, o que pode interferir positivamente na dieta humana. Os biofertilizantes são uma opção interessante em sistemas alternativos de produção, pois podem aumentar a qualidade nutricional dos alimentos e contribuir para o desenvolvimento das plantas, ao mesmo tempo que auxiliam na sustentabilidade do meio ambiente como produtos naturais. O uso de microalgas e ácido húmico como biofertilizante aponta para melhorias no teor de nutrientes e biomoléculas nas plantas, porém sua aplicação conjunta ainda é inexplorada. Nesse cenário, foi realizado um estudo com cebolas sobre a influência das aplicações via imersão radicular em soluções de microalgas Scenedesmus subspicatus (Sc) e ácido húmico (HA), analisando possíveis alterações de macro e micronutrientes, açúcares totais, açúcares redutores, sólidos solúveis totais, aminoácidos livres totais, proteínas solúveis e capacidade antioxidante nos bulbos. Os tratamentos consistiram na imersão das raízes das mudas de duas cultivares de cebola em soluções contendo microalgas e ácido húmico por um minuto, e posteriormente transplantadas para o campo do sistema orgânico. Foram utilizadas três concentrações: controle, 0,3 g L-1 Sc + 0,3 g L-1 HA (3SH) e 0,6 g L-1 Sc + 0,6 g L-1 HA (6SH). Os resultados mostram que os tratamentos com microalgas com associação de ácidos húmicos foram capazes de aumentar o teor de N, carboidratos e proteínas solúveis, elevando também a atividade antioxidante em bulbos de cebola.

The demand for soybean has increased in the international market, and water restriction is an important factor in reducing its yield. Therefore, the development of technologies aimed to reducing the damage caused by water stress becomes strategic. Thus, the objective was to demonstrate the role of the amino acid L-glutamic acid in mitigating water stress in soybean plants. A study was conducted in a greenhouse using soybean plants in vegetative stage subjected to water restriction and foliar applications of biofertilizer obtained from bacterial fermentation, containing 25% of the amino acid L-glutamic acid, sprayed three days before the imposition of water restriction and when the substrate moisture reached 50% of the water retention capacity (WRC). Stomatal resistance was determined throughout the days and three collections of plant material were carried out: at the beginning of water restriction, one and four days after rehydration for biochemical and enzymatic analyses. Plants that were supplied with biofertilizer at the beginning of water restriction showed lower stomatal resistance, while plants that received application three days before 50% WRC showed increases in sugar accumulation, in free amino acids and proline content, and in nitrate reductase and peroxidase enzymes activity, consequently, reducing lipids peroxidation, mitigating the effects of oxidative stress. La soya tiene una demanda creciente en el mercado mundial, siendo la restricción hídrica un factor importante en la reducción de la productividad. Por ende, el desarrollo de tecnologías orientadas a mitigar los daños causados por el estrés hídrico se torna estratégico. Por lo tanto, el objetivo fue demostrar el papel del aminoácido ácido L-glutámico en la mitigación del estrés hídrico en plantas de soya. El estudio se llevó a cabo en invernadero con plantas de soya en etapa vegetativa sometidas a restricción hídrica con aplicaciones foliares de 1 mL L-1 de un biofertilizante obtenido a partir de fermentación bacteriana conteniendo 25% del aminoácido L-glutámico, 3 días antes de imponer la restricción hídrica y cuando la humedad del sustrato alcanzó el 50% de la capacidad de retención de agua (CRA). Se determinó la resistencia estomática con el pasar de los días y se realizaron tres recolecciones de material vegetal: al inicio de la restricción hídrica, un y cuatro días después de la rehidratación para análisis bioquímicas y enzimáticas. Las plantas que recibieron aplicación de biofertilizante al inicio de la restricción hídrica presentaron menos resistencia estomática, mientras que las plantas que recibieron aplicación tres días antes de CRA50% mostraron incrementos en la acumulación de azucares, en la actividad de la enzima reductasa de nitrato, de aminoácidos libres, en el contenido de prolina y en la enzima peroxidasa. Consecuentemente, se corroboró la reducción del daño causado por la restricción hídrica, con una reducción de la peroxidación lipídica en los tratamientos con aplicación de biofertilizante, mitigando los efectos del estrés oxidativo en plantas de soya. A soja tem crescente demanda no mercado mundial, sendo a restrição hídrica um importante fator de redução da sua produtividade. Portanto, o desenvolvimento de tecnologias visando a mitigação dos danos causados pelo estresse hídrico torna-se estratégico. Desse modo, objetivou-se demonstrar o papel do aminoácido ácido L-glutâmico na mitigação do estresse hídrico em plantas de soja. O estudo foi conduzido em casa de vegetação com plantas de soja em estágio vegetativo submetidas a restrição hídrica com aplicações foliares de 1 ml L-¹ de um biofertilizante obtido de fermentado bacteriano contendo 25% do aminoácido ácido L-glutâmico, 3 dias antes da imposição da restrição hídrica e quando a umidade do substrato atingiu 50% da capacidade de retenção de água (CRA). Determinou-se a resistência estomática no decorrer dos dias e procederam-se três coletas de material vegetal: no início da restrição hídrica, um e quatro dias após a reidratação para analises bioquímicas e enzimáticas. As plantas que receberam aplicação do biofertilizante no início da restrição hídrica apresentaram menor resistência estomática, enquanto as plantas que receberam aplicação 3 dias antes de CRA50% apresentaram aumentos no acúmulo de açúcares, na atividade da enzima redutase do nitrato, de aminoácidos livres, no teor de prolina e na enzima peroxidase. Por consequência, verificou-se a redução dos danos causados pela restrição hídrica com redução da peroxidação lipídica nos tratamentos com aplicação do biofertilizante, mitigando os efeitos do estresse oxidativo em plantas de soja.

The aim of this work was study the use of an experimental product containing chitosan and chelated cooper (Cu) as a sustainable tool for the protection of tomato plants, to understand which are the mechanisms involved in resistance promotion and what could be the anatomical changes on tomato leaves related to those defense responses. The experiment was conducted in a greenhouse with tomato plants grown in pots and subjected to weekly foliar sprays of a suspension containing chitosan associated with Cu-EDTA (ChiCu). The increase in the phenolic compound concentrations and phenylalanine ammonia-lyase (PAL) enzyme activities were detected 24 hours after. In addition, an increase was observed in the activity of chitinase and β-1,3-glucanase, enzymes related to defense responses. Also, an increase was found in the thickness of the outer periclinal wall on the adaxial epidermal surface in leaves submitted to 4 ml L-1 ChiCu. The proportion of the epiderm to the leaf blade was also higher. Although the pathogenicity-related enzymes were activated as well as phenolic compounds were increased, these changes did not affected the biometric and biochemical parameters related to the primary metabolism and essential for the maintenance of productive potential of tomato plants. The increase in the outer periclinal wall as a result of ChiCu sprays could have contributed to the resistance against diseases since it is the first barrier to the infection of a wide of pathogens.

The identification of natural bioactive sources capable of enhancing yield gains on agriculture is a tool to promote sustainability. In this study, the effect of foliar applications of sugarcane molasses fermented by the bacteria Corynebacterium glutamicum, containing 30% (w/v) of the amino acid L-glutamic acid was tested on organically grown potato for two seasons. Four foliar applications at intervals of ten days were made using solutions with different concentrations of the fermented broth (0.2, 0.4, 0.6, 0.8 mL L-1). Total and commercial potato yield and biochemical alterations on leaves at 50 and 60 days after planting were determined. The applications of the fermented broth promoted yield gains and changes in chlorophylls, carotenoids, nitrate reductase enzyme (EC 1.6.6.1) activity, delaying the senescence and improving the free amino acid and soluble protein content of leaves. It was concluded that the fermented broth was able of improving potato yield by stimulating the nitrate reductase activity.

Made available in DSpace on 2018-12-11T16:48:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-02-01 Developing new and natural sources of plant growth promotors is essential to ensure the safe and sustainable production of vegetables for human consumption. In recent years, the potential of microalgae as plant biostimulants has been investigated. Arthrospira platensis (Spirulina platensis) biomass is a recognized protein source and its enzymatic hydrolysis contains molecules such as polyamines with potential to promote plant growth. Therefore, the aim of the present study was to investigate the biostimulant properties of hydrolyzed biomass of A. platensis. Bioassays were performed to determine auxin-like and cytokinin-like bioactivity of the hydrolysates. In addition, its effect on lettuce seedling growth was investigated and an organic system field trail performed where yield and free polyamine levels in leaves quantified. The hydrolysates had a cytokinin-like effect in the bioassay. Foliar applications promoted the growth of lettuce seedlings with the 4-h reaction hydrolysate (Sph4) being the most effective at promoting growth and increasing the spermine content by 64% in the lettuce leaves. The polyamine concentration was also compared in non-hydrolyzed A. platensis and Sph4. Hydrolysis resulted in a 34% increase in spermine content. It was concluded that Sph4 is a natural plant growth promoter that can be used as a raw material for biostimulants, and spermine could be an active compound and a metabolic indicator of Sph4 bioactivity. Universidade Federal do Paraná, Rua dos Funcionários, 1540 Széchenyi István University, Győr University of KwaZulu Natal Pietermaritzburg Universidade Estadual Paulista – UNESP Universidade Estadual Paulista – UNESP

The search for new natural sources for plant growth promotion and yield gains can contribute to ensuring safe and sustainable vegetable production. The potential of microalgae as a plant biostimulant source has been investigated in recent years, while the use of humic substances is well established; however the study of the combination of both is novel, and is the aim of this work. A step-by-step approach was adopted, conducting three experiments using the microalgae Scenedesmus subspicatus combined with humic acid: i) rooting bioassays in a growth chamber to identify bioactivity of microalgae, humic acid and their mixtures using Vigna radiata as a model plant. ii) immersion treatments of two onion cultivar seedlings at transplantation which were then grown in pots in a greenhouse, iii) immersion treatments of two onion cultivar (open-pollinated and hybrid) seedlings at transplantation which were then grown at field in organic system. Growth and biochemical variables, yield and nutrient content of onion leaves and bulbs were evaluated. The bioactivity of microalgae biomass, of humic acid and their mixtures were identified on bioassays, and synergy was found. The immersion of onion seedlings in microalgae plus humic acid solutions showed growth promoting effects at the early stages, improved bulb caliber and yield of the hybrid cultivar, and incremented sugars and proteins content in bulbs. The yield gain was not related to nutrients uptake stimuli.

Plant Production Department Agronomic Science College Sao Paulo State University (UNESP), Botucatu, Sao Paulo, cep 18.603-970

Plant Production Department Agronomic Science College Sao Paulo State University (UNESP), Botucatu, Sao Paulo, cep 18.603-970

No presente trabalho, objetivou-se avaliar os efeitos da aplicação foliar do extrato da alga Ascophyllum nodosum, do ácido L-glutâmico e do Ca+2, no crescimento e produção de plantas de feijão (Phaseolus vulgaris L.). O experimento foi conduzido em casa de vegetação com os seguintes tratamentos: testemunha; aplicações foliares de soluções contendo 60 g L-1 de ácido L-glutâmico; contendo 60 g L-1 de extrato de alga; contendo 100 g L-1 de Ca+2 na forma de CaCl2; contendo 30 g L-1 de ácido L-glutâmico e 30 g L-1 extrato de alga; contendo 30 g L-1 de ácido L-glutâmico e 100 g L-1 de Ca+2; contendo 30 g L-1 de extrato de alga e 100 g L-1 de Ca+2; contendo 15 g L-1de ácido L-glutâmico associado a 15 g L-1 de extrato de alga e 100 g L-1 de Ca+2, aos 12, 28 e 42 dias após a emergência das plantas. Para a aplicação foliar, cada solução foi diluída em água na concentração de 3 ml L-1. Ao longo do ciclo foram avaliadas variáveis biométricas e ao final quantificou-se a produção de grãos por planta. Identificou-se o efeito dos tratamentos no crescimento inicial, ao longo do ciclo das plantas e na produção de grãos, caracterizando o efeito bioestimulante da solução contendo 30 g L-1 de extrato de alga e 100 g L-1 de Ca+2, e da solução contendo 15 g L-1de ácido L-glutâmico associado a 15 g L-1 de extrato de alga e 100 g L-1 de Ca+2.

The use of microalgae as natural biofertilizer in horticulture has recently been reported, while the use of humic substances is widespread. However, the combined use of microalgae with humic substances applied to plant leaves is still unexploited. Thus, the objective of this work was to combine fulvic acid (FA) with the Scenedesmus subspicatus microalga biomass (SC) as a natural biofertilizer applied via leaf in two onion cultivars in organic system. Four experiments were conducted: i) bioassays to verify the bioactive effect of FA, SC and combinations using the Vigna radiata model plant; ii) greenhouse pot experiment with foliar applications of FA, SC and combination in two onion cultivars; iii) field experiment in organic system with foliar applications of FA, SC and combination in two onion cultivars; and iv) onion bulb storage experiment. The bioactive effect of SC, FA and their combinations was identified by promoting changes in root growth of V. radiata. In pots, treatments containing FA, SC and combination promoted increase in fresh and dry leaf mass. The foliar application of FA, SC and combination promoted an increase in field bulb productivity, reduced mass loss in stored bulbs and increased carbohydrate, amino acid and protein contents in onion bulbs.