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The objective of the study was to evaluate the effect of methyl jasmonate and ethephon on cotton against Fusarium wilt. As well, cotton plants were treated in the field by methyl jasmonate (MeJA), ethephon (ETH) and the association of methyl jasmonate and ethephon (MeJA + ETH) and inoculated by Fusarium oxysporum f. sp. Vasinfectum (FOV). The incidence of the disease caused by FOV was evaluated every 10 days up to the 150th day after inoculation. The protection afforded to cotton following treatment by stimulators was assessed by determining the mortality rate of plants treated and inoculated FOV compared with untreated and inoculated controls. The degree of protection of cotton from Fusarium wilt was also determined through growth parameters, foliar pigment content (Chlorophylls and carotenoids) and an evaluation of the rate of lines. The results showed better protection of the cotton plants treated by the stimulators and inoculated by FOV through an increase in the number of healthy leaves, stem height, and stem diameter. This protection was also confirmed by an increase in photosynthetic activity of plants and a reinforcement of cell walls. The combination of these two molecules (MeJA + ETH) was better to induce this resistance against FOV compared to each of the two taken separately. The use of natural defence stimulators (SDN) is therefore an effective means of protecting cotton from FOV. Their application in the agricultural environment could contribute to the development of a well-reasoned, sustainable agriculture that is more respectful of the environment and human health.

The oil palm (Elaeis guineensis Jacq.) genetic improvement is based on a recurrent reciprocal selection scheme, involving two groups of populations whose production components are complementary. Group A is essentially coming from Asia, while group B includes African oil palm populations. In order to increase genetic variability and to enrich the agronomic qualities of this group B, a survey was carried out in Western Côte d'Ivoire. Twelve traditional genotypes were collected in the Man area. They are known to produce a rather fluid palm oil but their behavior against Fusarium wilt was unknown. Therefore, these traditional populations were subjected to the Fusarium wilt tolerance test. One hundred and sixty (160) two-months-old seedlings of the traditional accessions were distributed in 8 completely randomized blocks and inoculated by Fusarium oxysporum f. sp. elaeidis. The appearance of external symptoms on inoculated plantlets was observed over the duration of 5 months, and internal symptoms remarked after plantlets dissection. Index of the Fusarium wilt susceptibility of each progeny was determined. A third of traditional genotypes tested (Dompleu Kp 03, Gbangbegouiné Doua 01, Gbangbegouiné Kla 01 and Gbatonguin Yod 02) proved to be highly tolerant to the wilt disease. Four traditional accessions (Bogouiné Sad 02, Dompleu Kp 01, Dimgouin Zoh 02 and Blolé Dio 05) showed low tolerance, while the last four traditional genotypes (Blolé Oul 03, Koutongouiné Iba 02, Blolé Dio 02 and Dompleu Dou 03) were sensitive to the wilt disease.

La fusariose causee par Fusarium oxysporum f. sp. vasinfectum est une maladie qui entraine le plus de dommages dans la culture cotonniere. Cependant, l’utilisation de pesticides notamment les fongicides comme solution pour faire face a l’agent pathogene s’est averee non seulement inefficace mais entraine des problemes de toxicite, de pollution de l’environnement, de sante et meme de biodiversite. L’objectif de ce travail a ete d’etudier la variabilite de la production de composes phenoliques impliques dans le systeme de defense naturelle du cotonnier. Ainsi, l’application des eliciteurs MeJA et FOS11 (10%) sur les plants de cotonnier suivis d’inoculation a FOV a permis la synthese de novode composes phenoliques en plus des composes preexistants. Par ailleurs, l’accumulation des composes phenoliques a ete amplifiee suite a l’application de ces deux eliciteurs suivie de l’inoculation a FOV. Les plants de cotonnier ont ete donc equipes de composes qui ont anticipes l’attaque de FOV. Toutefois, la FOS11 (10%) a induit la production d’un plus grand nombre de composes phenoliques que le MeJA. La FOS11 (10%) a donc ete retenu comme meilleur eliciteur naturelle de la stimulation des defenses naturelles du cotonnier. Fusarium blight caused by Fusarium oxysporum f. sp. vasinfectum is a disease that causes the most damage in cotton growing. However, the use of pesticides, especially fungicides as a solution to the pathogen, has proven to be not only ineffective but also leads to problems of toxicity, environmental pollution, health and even biodiversity. The objective of this work wasto study the variability of the production of phenolic compounds involved in the natural defense system of the cotton plant. Thus, the application of the MeJA and OSF 11 elicitors (10%) on the cotton plants followed by inoculation with FOV allowed the de novo synthesis of phenolic compounds in addition to the preexisting compounds. Moreover, the accumulation of phenolic compounds was amplified following the application of these two elicitors followed by inoculation with FOV. The cotton plants were therefore equipped with compounds that anticipated the FOV attack. However, OSF 11 (10%) induced the production of more phenolic compounds than MeJA. OSF 11 (10%) was therefore chosen as the best natural elicitor of the stimulation of the natural defenses of cotton.