Moroccan seaweed polysaccharides elicit defense response and induce protection against Botrytis cinerea in tomato plants

Eight Polysaccharides Enriched Extracts (PEEs) obtained from Moroccan seaweeds were selected to test their effectiveness on the natural defense of tomato plants. Firstly, we examined the effect of the 8 PEEs at 4 concentrations (0.02, 0.05, 0.1 and 0.2 mg. mL-1) with 3 application methods (T1: root irrigation, T2: foliar spray, and T3: combining the 2 methods T1 and T2) on protein content and plant defense enzyme: Phenylalanine Ammonia-lyase (PAL) on tomato plants in absence of a pathogen. In the second part, we analyzed the ability of PEEs to induce protection against Botrytis cinerea, causative agent of gray mold, by testing PEEs on detached tomato leaves. Results showed that the PEEs obtained from Codium tomentosum, Ulva rigida, and Bifurcaria bifurcata at 0.1 mg. mL-1 and Gelidium crinale, Schizymenia dubyi and Fucus spiralis at 0.02 mg. mL-1 were the best treatments that significantly stimulated protein content and PAL activity in tomato plants with the three application methods. The same extracts at the same concentrations, in addition of PEEs from G. pistillata at 0.02 mg. mL-1 were the treatments having the greatest inhibitory effect on the diameter lesion of B. cinerea in detached leaves when compared to the control. The principal component analysis showed a correlation between PAL content and the reduction of diameter lesion. The comparison of the application method in our study did not show differences. These findings confirmed that these algal polysaccharides treatments could be a promising method to reduce dependency on synthetic fungicides. The presence of uronic acid and sulfated groups in the extracts could explain the elicitation mechanism induced in plant cells.  Keywords: Tomato plants; PEEs; seaweeds; plant defense, PAL, Botrytis cinere

Utilisation des polysaccharides des algues marines comme biostimulants en horticulture

In order to meet the food needs of populations, it has become essential to improve crop yields in an ecological and sustainable way while reducing the use of chemical inputs which have negative impacts on the environment and living beings. Innovative technology to address these important challenges involves the development of novel plant biostimulants (PBs) and effective methods for their applications. Over time, macroalgae (seaweed) and its extracts are used as fertilizers, being cost effective and environmentally friendly and have shown a significant increase in crop yield globally. Recent studies suggest that biostimulants based on polysaccharides extracted from seaweed could be a solution to this problem. Application of these extracts has been shown to improve nutrient uptake and improve crop growth performance under stress and normal conditions. In this article, we review the role of these extracts as plant biostimulants and current studies of their uses in stimulating seed germination and the growth and elicitation of natural plant defense systems. This review article therefore focuses on the exploitation of seaweed extracts in agricultural activities as part of an eco-sustainable green technology. Keywords: Plant biostimulants, algal polysaccharides, plant growth, natural plant defenseAfin de satisfaire les besoins des populations en nourriture, il est devenu indispensable d’améliorer le rendement des cultures de manière écologique et durable tout en diminuant l’utilisation des intrants chimiques qui ont des impacts négatifs sur l’environnement et les êtres vivants. Une technologie innovante pour relever ces défis importants implique le développement de nouveaux biostimulants des plantes (PB) et de méthodes efficaces pour leurs applications. Au fil du temps, les macroalgues (algues) et leurs extraits sont utilisées comme engrais, étant rentables et respectueux de l'environnement et ont montré une augmentation significative du rendement des cultures à l'échelle mondiale. Des études récentes suggèrent que les biostimulants à base de polysaccharides extraits d’algues pourraient être une solution à ce problème. Il a été démontré que l’application de ces extraits améliorent l'absorption des nutriments et améliorent les performances de croissance des cultures dans des conditions de stress et normales. Dans cet article, nous passons en revue le rôle de ces extraits en tant que biostimulants végétaux et les études actuels de leurs utilisations sur la stimulation de la germination des graines et la croissance et l’élicitation des systèmes de défense naturelle des plantes. Cet article de synthèse met donc l'accent sur l'exploitation des extraits d’algues dans les activités agricoles dans le cadre d'une technologie verte éco-durable. Mots clés: Biostimulants des plantes, polysaccharides algaux, croissance des plantes, défense naturelle des plante

Irrigation à la raie : une technique pour l'amélioration du drainage et de la valorisation de l'eau dans la plaine du Gharb au Maroc

International audienceThe Gharb plain in Morocco suffers from water excess in winter and from water deficit during the spring and summer. This explains the low profitability of the investments in irrigation agreed by the Moroccan state and low yields of winter crops. Furrow irrigation systems may be a way to increase water productivity by improving the surface drainage in winter, and by irrigating the crops efficiently in spring and summer. The aim of this study was to assess the hydraulic performance of furrow systems and its agronomic impacts based on an experimental and a modelling approach. Yields were simulated for a series of 11 climatic years (19952006). Results clearly showed the advantage of the furrow system whatever the sowing dates. These results confirmed that to improve the water productivity of winter crops in the context of the Gharb scheme, attention has to be paid to surface drainage

Algae biostimulants: A critical look at microalgal biostimulants for sustainable agricultural practices

For the growing human population to be sustained during present climatic changes, enhanced quality and quantity of crops are essential to enable food security worldwide. The current consensus is that we need to make a transition from a petroleum-based to a bio-based economy via the development of a sustainable circular economy and biorefinery approaches. Both macroalgae (seaweeds) and microalgae have been long considered a rich source of plant biostimulants with an attractive business opportunity in agronomy and agro-industries. To date, macroalgae biostimulants have been well explored. In contrast, microalgal biostimulants whilst known to have positive effects on development, growth and yields of crops, their commercial implementation is constrained by lack of research and cost of production. The present review highlights the current knowledge on potential biostimulatory compounds, key sources and their quantitative information from algae. Specifically, we provide an overview on the prospects of microalgal biostimulants to advance crop production and quality. Key aspects such as specific biostimulant effects caused by extracts of microalgae, feasibility and potential of co-cultures and later co-application with other biostimulants/biofertilizers are highlighted. An overview of the current knowledge, recent advances and achievements on extraction techniques, application type, application timing, current market and regulatory aspects are also discussed. Moreover, aspects involved in circular economy and biorefinery approaches are also covered, such as: integration of waste resources and implementation of high-throughput phenotyping and -omics tools in isolating novel strains, exploring synergistic interactions and illustrating the underlying mode of microalgal biostimulant action. Overall, this review highlights the current and future potential of microalgal biostimulants, algal biochemical components behind these traits and finally bottlenecks and prospects involved in the successful commercialisation of microalgal biostimulants for sustainable agricultural practices