Effects of plant growth promoting rhizobacteria (PGPR) on Citrus macrophylla rootstock

Citrus is one of the largest fruit crops grown in Morocco. Citrus crops gain in importance due to the jobs generated during the production process of fresh or processed fruit. Intensive agriculture is characterized by the excessive use of inorganic fertilizers and pesticides. This production system has generated serious environmental contamination problems, thus, it is necessary to implement sustainable production strategies to reduce the use of synthetic chemicals and contribute to soil and water conservation. In this context, Seventy two Rhizobacterial isolates of fluorescent Pseudomonas were isolated from rhizosphere soil of Citrus in the Sapiama nursery. These isolates were tested on germination and growth of Citrus macrophylla rootstock. The results obtained showed that the isolate C11 significantly stimulated germination 16 days after seed inoculation. The C26, C6 and C24 isolates showed PGPR effects improving significantly the growth parameters of C. macrophylla rootstock. They significantly promoted plant height, collar diameter and root length. This study concluded that the Pseudomonas isolates could be potential alternative biofertilizers to chemical products and could be considered as a promising main component for sustainable agriculture development strategy in Citrus farming. Keywords: Citrus macrophylla, Pseudomonas, PGP

The effect of Leonardite humic substances on the growth and vegetative propagation of saffron (Crocus sativus L.)

Le safran (Crocus sativus L.) est une espèce géophyte triploïde stérile (2n=3x=24) à floraison automnale et appartenant à la famille des Iridacées. Cette plante triploïde se propage par reproduction végétative par la formation de cormes filles à partir des cormes mère, car les fleurs sont stériles et ne produisent pas de graines viables. En fait, de nombreux facteurs entravent la propagation efficace du safran par cette pratique traditionnelle et les faibles taux de multiplication des cormes dans les conditions naturelles réduisent la productivité, limitant ainsi la disponibilité du matériel de plantation. Ainsi, l'objectif principal de ce travail est de tester l'effet des substances humiques (SH) sur la croissance et la multiplication végétative du safran. Les principaux résultats des essais indiquent que les SH améliorent la croissance et le développement du safran, et l'intensité de la réponse dépend de la concentration utilisée et du mode d'application. En fait, le traitement temporaire des cormes avec les SH (50 et 100 ppm) a amélioré la croissance des plantes et des cormes filles mais n'a pas d’effet significatif sur le nombre de pousses et de cormes filles.Saffron (Crocus sativus L.) is an autumn-flowering and sterile triploid (2n=3x=24) geophyte species that belong to the Iridaceae family. This triploid plant is propagated by vegetative reproduction through the formation of daughter corms from the mother corm, as the flowers are sterile and fail to produce viable seeds. In fact, many factors hamper the efficient propagation of saffron through this traditional practice and the low multiplication rates of daughter corms under natural conditions reduce productivity, thereby restraining the availability of planting material. Thus, the main objective of this work is to test the effect of humic substances (HS) on saffron vegetative propagation. The main results of trials indicate that HS improves the saffron plant's growth and development, and the intensity of response depends on the concentration used and the mode of application. In fact, the temporary treatment of corms with HS (50 and 100 ppm) improved plant and daughter corms growth but did not affect the number of shoots and corms

Optimization of the explant disinfection method and in vitro multiplication of saffron (Crocus sativus L.).

Saffron (Crocus sativus L.), renowned as the world’s most expensive spice extracted from its stigmas, is an autumn-flowering, sterile triploid geophyte species (2n=3x=24) belonging to the Iridaceae family. It is propagated vegetatively through the development of daughter corms from the mother corm. Low multiplication rates of daughter corms under natural conditions and many biotic and abiotic stresses reduce productivity, thereby restraining the availability of planting material. Thus, the main objective of this work is to improve the vegetative propagation of saffron through tissue culture. The results show that soaking of explants in 0.1% (w/v) mercury chloride (HgCl2) for 10 min is more effective for explant disinfection (95%), with a survival rate of over 85%. Whereas, for the initiation phase, the in vitro culture of whole corms on Murashige and Skoog (MS) medium supplemented with 0.5 mg /L of 1-naphthalene acetic acid (NAA) in combination with 3 mg/L of 6-benzylaminopurine (BAP) was more effective, resulting in a sprouting rate of 90% with a maximum of 5 sprouted buds per explant. As for the multiplication phase, the highest number of shoots (4 shoots/single shoot explant) was observed on MS medium supplemented with 8 mg/L of BAP in combination with 0.5 mg/L of NAA. The results of this study can serve as a starting point for establishing an efficient and reproducible in vitro regeneration system in order to increase the number of shoots per explant for proliferation and micro-corms formation phases by exploring other culture media with different PGR combinations

Antifungal activity of four plant extracts against Botrytis cinerea

Botrytis cinerea, responsible for the gray mold disease of tomato, is one of the main problems in fruit exporting countries. Synthetic antifungals are used for their control. However, these products lead to serious damage to environment ant human. Furthermore, it has developed a resistance towards many of them. Therefore, the use of botanical biopesticides as natural alternatives that are friendly to the environment has increased in the last decade. The objective of the present study is the evaluation of the antifungal activity of extracts of four plants, Marrubium vulgare, Moringa oleifera, Psidium guajava and Casimiroa edulis against B. cinerea and the phytochemical characterization of these extracts. The extraction was carried out by maceration, decoction, and ultrasonic-assisted extraction. The high extraction yields of 18.91%, 31.05%, 33.01% and 24.67% were obtained respectively with maceration for M. vulgare, M. oleifera, P. guajava and C. edulis. Qualitative phytochemical tests revealed the presence of terpenoids in all extracts, while saponosides were present only in a few extracts. The highest contents of polyphenols were noted for P. guajava and C. edulis. Also, the highest flavonoid content was noted for C. edulis and M. oleifera. The evaluation of the activity of the studied extracts against the mycelial growth and the germination of the spores of B. cinerea showed that the extracts obtained by maceration and by ultrasonic-assisted extraction of P. guajava and C. edulis are the most efficient against the mycelial growth with an inhibition percentage of 100% for all the tested concentrations. Similarly, the maceration extract of M. vulgare allowed the total inhibition of the germination of the pathogen spores. Finally, the extracts of M. oleifera were the least effective against B. cinerea

Self- and Cross-Pollination in Argane Tree and their Implications on Breeding Programs

The argane tree (Argania spinosa L.) is a mostly self-incompatible species that must be cross-pollination. However, the cross-pollination is often insufficient to obtain a desirable fruit yield in the absence of compatibility between the orchard’s argane trees. Proper pollination design is therefore essential to ensure a supply of compatible pollen. In this study, pollen germination and pollen development following cross- and self-pollination were investigated in A. spinosa. The choice of compatible parents or a pollinizer is currently a new research topic for the production of argane fruits in the framework of argane farming programs. Different pollination experiments were designed with two main objectives: (i) to study cross/self-(in)compatibility in the argane tree, and (ii) to determine the degree of compatibility between selected superior genotypes for pollination strategies to improve fruit set in argane orchards. Thus, to determine if a pollination deficit exists, experiments were carried out on 14 genotypes, and 5421 flowers served as sampling. The germination rate of pollen was lower than 50% for three genotypes, and only four genotypes bloom twice a year. From cross-pollination trials, traits related to the mother trees, such as the shape of the fruit and fruit ripening duration, are not influenced by the gene flow transmitted by pollens. Self-pollination was very low (0.2%) for both hand- and free self-pollination but the highest fruit set rate observed was 5.3%. Based on the pollen effect study results, it can be concluded that different pollen sources affected the fruit set. Thus, the choice of an efficient pollinizer genotype must be inter-compatible with the main variety, bloom at the same time, and be regular (no alternation). This is the first time that a pollinizer tree was reported and studied for argane. To meet future argane farming requirements, the number and location of compatible pollinizers is very important in the argane orchard design. This design of pollination remains to be checked by alternately planting a row of pollinizer trees or inter-rows with main varieties

Structure florale et arbre pollinisateur comme facteurs fiables pour le système de croisement d'Argania spinosa

In most breeding programs the pollen donor parents (pollinizers) are characterized by a strong flowering rate and very low fruit set, even after hand pollination. Hence, the notion of pollinizers in the argane species was born, first mentioned, checked, documented and confirmed like in the other conventional tree species. Since the argane tree is completely self-incompatible, the presence of compatible pollinizers is necessary for the fruit set. Indeed, pollinizers need to be selected accurately based on the synchronization of bloom periods and compatibility to receiver trees (females). The pollinizer is essential in any breeding program and as well as for any new orchard plantations. The current study was carried out on 13 argane genotypes including two pollinizers. The flowering period, bloom phenology, floral structure and fruit set of crossed genotypes were monitored, illustrated and a season phenogram was established. The pollen viability and germination were also evaluated. Concerning compatibility trials, the hand pollination, using two selected pollinizers pollens, was compared to open pollination. Then, the compatibility system was monitored and evaluated through the index of self-incompatibility. It has been observed that the flowering periods are genotype depending, that there is one to three blooms during the two years study (2018-2019) and that the argane tree is a tristylous species (Mesostylous, brevistylous and longistylous flowers). The in vitro tests showed that the pollen originated from crossed genotypes were viable and able to germinate. The cross-compatibility rate depends on cross associations and it varies from 39 to 84 %. It was observed, for the first time, that all compatible pollinizers have metaxenic effects of pollen on argane fruit.Au cours des programmes d’amélioration génétique, les parents donneurs de pollen (pollinisateurs) se caractérisent par une forte intensité florale et une très faible nouaison, même après une pollinisation manuelle. C’est ainsi que la notion de pollinisateurs pour l'espèce d'arganier est née, d'abord évoquée, vérifiée, documentée et confirmée comme pour d'autres espèces d'arbres. L'arganier étant totalement auto-incompatible, la présence de pollinisateurs compatibles est nécessaire à la nouaison. Ces pollinisateurs doivent être sélectionnés avec précision en fonction de la synchronisation des périodes de floraison et de la compatibilité avec les arbres récepteurs (femelles). Le pollinisateur est essentiel aussi bien dans tout programme d’amélioration génétique que pour les plantations de nouveaux vergers. La présente étude a été menée sur 13 génotypes d'arganier dont deux pollinisateurs. La période de floraison, la phénologie de la floraison, la structure florale et la nouaison des génotypes croisés ont été suivies, illustrées et un phénogramme de saison a été établi. La viabilité et la germination du pollen ont également été évaluées. En matière de compatibilité, la pollinisation manuelle utilisant deux pollinisateurs sélectionnés a été comparée à la pollinisation libre. Ensuite, le système de compatibilité a été surveillé et évalué à travers l'indice d'auto-incompatibilité. Il a été constaté que les périodes de floraison dépendent du génotype, qu’il y a eu une à trois période de floraisons au cours des deux années d'étude (2018-2019) et que l'arganier est une espèce tristyle (fleurs mésostyleuses, brévistyles et longistyles). Les tests in vitro ont montré que le pollen issu de génotypes croisés était viable et capable de germer. Le taux de compatibilité croisée dépend des associations croisées et il varie de 39 à 84 %. Il a été observé, pour la première fois, que pour des pollinisateurs compatibles, des effets métaxéniques du pollen sur les fruits de l'arganier se sont produits

Effet des substances humiques de la Leonardite sur la croissance et la multiplication végétative du safran (Crocus sativus L.)

Saffron (Crocus sativus L.) is an autumn-flowering and sterile triploid (2n=3x=24) geophyte species that belong to the Iridaceae family. This triploid plant is propagated by vegetative reproduction through the formation of daughter corms from the mother corm, as the flowers are sterile and fail to produce viable seeds. In fact, many factors hamper the efficient propagation of saffron through this traditional practice and the low multiplication rates of daughter corms under natural conditions reduce productivity, thereby restraining the availability of planting material. Thus, the main objective of this work is to test the effect of humic substances (HS) on saffron vegetative propagation. The main results of trials indicate that HS improves the saffron plant's growth and development, and the intensity of response depends on the concentration used and the mode of application. In fact, the temporary treatment of corms with HS (50 and 100 ppm) improved plant and daughter corms growth but did not affect the number of shoots and corms.Le safran (Crocus sativus L.) est une espèce géophyte triploïde stérile (2n=3x=24) à floraison automnale et appartenant à la famille des Iridacées. Cette plante triploïde se propage par reproduction végétative par la formation de cormes filles à partir des cormes mère, car les fleurs sont stériles et ne produisent pas de graines viables. En fait, de nombreux facteurs entravent la propagation efficace du safran par cette pratique traditionnelle et les faibles taux de multiplication des cormes dans les conditions naturelles réduisent la productivité, limitant ainsi la disponibilité du matériel de plantation. Ainsi, l'objectif principal de ce travail est de tester l'effet des substances humiques (SH) sur la croissance et la multiplication végétative du safran. Les principaux résultats des essais indiquent que les SH améliorent la croissance et le développement du safran, et l'intensité de la réponse dépend de la concentration utilisée et du mode d'application. En fait, le traitement temporaire des cormes avec les SH (50 et 100 ppm) a amélioré la croissance des plantes et des cormes filles mais n'a pas d’effet significatif sur le nombre de pousses et de cormes filles

Optimisation de la méthode de désinfection des explants et multiplication in vitro du safran (Crocus sativus L.).

Saffron (Crocus sativus L.), renowned as the world’s most expensive spice extracted from its stigmas, is an autumn-flowering, sterile triploid geophyte species (2n=3x=24) belonging to the Iridaceae family. It is propagated vegetatively through the development of daughter corms from the mother corm. Low multiplication rates of daughter corms under natural conditions and many biotic and abiotic stresses reduce productivity, thereby restraining the availability of planting material. Thus, the main objective of this work is to improve the vegetative propagation of saffron through tissue culture. The results show that soaking of explants in 0.1% (w/v) mercury chloride (HgCl2) for 10 min is more effective for explant disinfection (95%), with a survival rate of over 85%. Whereas, for the initiation phase, the in vitro culture of whole corms on Murashige and Skoog (MS) medium supplemented with 0.5 mg /L of 1-naphthalene acetic acid (NAA) in combination with 3 mg/L of 6-benzylaminopurine (BAP) was more effective, resulting in a sprouting rate of 90% with a maximum of 5 sprouted buds per explant. As for the multiplication phase, the highest number of shoots (4 shoots/single shoot explant) was observed on MS medium supplemented with 8 mg/L of BAP in combination with 0.5 mg/L of NAA. The results of this study can serve as a starting point for establishing an efficient and reproducible in vitro regeneration system in order to increase the number of shoots per explant for proliferation and micro-corms formation phases by exploring other culture media with different PGR combinations.Le safran (Crocus sativus L.), reconnu comme l'épice la plus chère au monde obtenu à partir des stigmates, est une espèce géophyte triploïde stérile (2n=3x=24) à floraison automnale et qui appartient à la famille des Iridacées. Il se propage végétativement grâce à la formation de cormes filles à partir du corme mère. Le faible taux de multiplication des cormes filles dans les conditions naturelles conjugué à l’effet de nombreux stress biotiques et abiotiques réduisent la productivité, limitant ainsi la disponibilité du matériel végétal de plantation. Ainsi, l'objectif principal de ce travail est d'améliorer la propagation végétative du safran par la culture des tissues in vitro. Les résultats montrent que le trempage des explants dans 0,1 % (p/v) de chlorure de mercure (HgCl2) pendant 10 min est plus efficace pour la désinfection des explants (95 %) avec un taux de survie de plus de 85 %. Alors que pour la phase d'initiation, la culture des cormes entiers sur milieu de Murashige et Skoog (MS) additionné de 0,5 mg/L d’acide 1-naphtalène acétique (ANA) en combinaison avec 3,0 mg/L de 6-benzylaminopurine (BAP) a été plus efficace puisqu'elle permet d’obtenir un taux de germination de 90% accompagné d’un maximum nombre de bourgeons germés (5 bourgeons/explant). Comme pour la phase de multiplication, le plus grand nombre de pousses (4 pousses/pousse initial) a été observé sur le milieu MS additionné de 8,0 mg/L de BAP en combinaison avec 0,5 mg/L d’ANA. Les résultats de cette étude peuvent servir de point de départ pour établir un système de régénération in vitro efficace et reproductible afin d'augmenter le nombre de pousses par explant pour les phases de prolifération et la formation de micro-cormes en explorant d'autres milieux de culture avec différentes combinaisons de PGR

Inoculation of tomato plants with rhizobacteria suppresses development of whitefly Bemisia tabaci (GENNADIUS) (HEMIPTERA: ALEYRODIDAE): Agro-ecological application.

In agroecosystems, soil biodiversity is increasingly becoming more recognized as providing benefits to both plants and human health. It performs a wide variety of ecological services beyond the recycling of nutrients to plant growth and manage pests and diseases below the economic injury level. This study investigated the effects of three Pseudomonas isolates (Q172B, Q110B and Q036B), isolated from untreated tomato rhizospheric soil, as a biological control agent of Bemisia tabaci which is a key pest of tomato crops. The study was conducted under laboratory and glasshouse conditions and the water treatment was used as a control. Adult mortality rates were assessed during three days at 24h interval and larva mortality rates were evaluated during six days after treatment at 48h interval. Results indicate that Q036B isolate has a faster effect on B. tabaci adult and larvae. Under laboratory conditions, all three Pseudomonas isolates (Q110B, Q036B and Q172B) have a significant effect on B. tabaci adult mortality compared to control. The earliest and the most important mortality rate of 76% was recorded by Q036B. Two isolates Q036B and Q110B caused a significant mortality on B. tabaci larvae; with highest mortality effect (79%) was observed for Q036B compared to control. However, Q172B has no mortality effects on B. tabaci larvae under laboratory conditions. In glasshouse conditions, only Q036B provided high mortality rates of 91% at 168h after treatment. The results of this study indicate that the Pseudomonas isolate Q036B significantly suppresses B. tabaci in tomato plant and could substitute the excessive use of chemicals. Current research indicates that soil biodiversity could be promising to preserve agro-ecological sustainability

Activité antifongique de quatre extraits de plantes contre Botrytis cinerea

Botrytis cinerea, responsible for the gray mold disease of tomato, is one of the main problems in fruit exporting countries. Synthetic antifungals are used for their control. However, these products lead to serious damage to environment ant human. Furthermore, it has developed a resistance towards many of them. Therefore, the use of botanical biopesticides as natural alternatives that are friendly to the environment has increased in the last decade. The objective of the present study is the evaluation of the antifungal activity of extracts of four plants, Marrubium vulgare, Moringa oleifera, Psidium guajava and Casimiroa edulis against B. cinerea and the phytochemical characterization of these extracts. The extraction was carried out by maceration, decoction, and ultrasonic-assisted extraction. The high extraction yields of 18.91%, 31.05%, 33.01% and 24.67% were obtained respectively with maceration for M. vulgare, M. oleifera, P. guajava and C. edulis. Qualitative phytochemical tests revealed the presence of terpenoids in all extracts, while saponosides were present only in a few extracts. The highest contents of polyphenols were noted for P. guajava and C. edulis. Also, the highest flavonoid content was noted for C. edulis and M. oleifera. The evaluation of the activity of the studied extracts against the mycelial growth and the germination of the spores of B. cinerea showed that the extracts obtained by maceration and by ultrasonic-assisted extraction of P. guajava and C. edulis are the most efficient against the mycelial growth with an inhibition percentage of 100% for all the tested concentrations. Similarly, the maceration extract of M. vulgare allowed the total inhibition of the germination of the pathogen spores. Finally, the extracts of M. oleifera were the least effective against B. cinerea.Botrytis cinerea, responsable de la moisissure grise de la tomate, est le principal problème des pays exportateurs de fruits. Des antifongiques synthétiques sont utilisés pour leur contrôle. Cependant, ces produits entraînent de graves dommages à l'environnement et à la santé humaine. En outre, il a développé une résistance à l’encontre de nombre de pesticides. Par conséquent, l’utilisation de biopesticides botaniques comme alternatives naturelles et respectueuses de l’environnement a augmenté au cours de la dernière décennie. L'objectif de la présente étude est l'évaluation de l'activité antifongique des extraits de quatre plantes, Marrubium vulgare, Moringa oleifera, Psidium guajava et Casimiroa edulis contre B. cinerea et la caractérisation phytochimique de ces extraits. L'extraction a été réalisée par macération, décoction et extraction assistée par ultrasons. Les rendements d'extraction les plus élevés ont été obtenus respectivement avec macération pour M. vulgare (18,91%), M. oleifera (31,05%), P. guajava (33,01%) et C. edulis (24,67%). Des tests phytochimiques qualitatifs ont révélé la présence de terpénoïdes dans tous les extraits, tandis que les saponosides n'étaient présents que dans quelques extraits. Les teneurs les plus élevées en polyphénols ont été notées pour P. guajava et C. edulis. En outre, la teneur en flavonoïdes la plus élevée a été obtenu chez C. edulis et M. oleifera. L'évaluation de l'activité des extraits étudiés contre la croissance mycélienne et la germination des spores de B. cinerea a montré que les extraits obtenus par macération et par extraction assistée par ultrasons de P. guajava et C. edulis sont les plus efficaces contre la croissance mycélienne avec un pourcentage d'inhibition de 100% pour toutes les concentrations testées. De même, l'extrait de macération de M. vulgare a permis l'inhibition totale de la germination des spores de cet agent pathogène. Enfin, les extraits de M. oleifera sont les moins efficaces contre B. cinerea