The propagation of Givotia rottleriformis Griff. is difficult as a result of long seed dormancy associated with poor seed germination. The present study was undertaken to develop a protocol to overcome seed dormancy by culture of zygotic embryo axes and then develop an efficient method for micropropagation of Givotia. Best germination frequency (78.3%) was achieved from mature zygotic embryo axes isolated from acidscarified fresh seeds when cultured on Murashige and Skoog (MS) medium (half-strength major salts) with 28.9 μM gibberellic acid (GA 3 ). Efficient plant conversion was achieved by transfer of 10-d-old germinated embryos to MS medium (half-strength major salts) supplemented with 1.2 μM kinetin (KN) and 0.5 μM indole-3-butyric acid (IBA). However, acid scarification of 1-yr-old seeds decreased the germination frequency of zygotic embryo axes in comparison to those obtained from non-acidscarified seeds which germinated (96.2%) and converted into plants (80.3%) on MS basal (half-strength major salts) medium. Multiple shoot bud induction was achieved by culture of shoot tips derived from in vitro germinated seedlings on MS medium with 0.5 μM thidiazuron for 4 wk, and the shoots elongated after transfer to a secondary medium with 1.2 μM KN. A maximum number of 7.8 shoots per explant with an average shoot length of 3.2 cm was achieved after two subcultures on this medium. The in vitro regenerated shoots rooted (41.5%) on half-strength MS medium with 0.5 μM IBA. The in vitro generated seedlings and micropropagated plants were established in soil with a survival frequency of 70% and 60%, respectively.

Resistance to internal browning of pineapple fruits depends on several factors such as the cultural techniques through mineral fertilization. The objective of this work is to study the effects of the potassium fertilization for pineapple on internal browning of fruit in post-harvest conservation. The experiments have been carried out on the site of the University Nangui Abrogoua (Abidjan, Côte d’Ivoire) of July 2015 to the end of October 2016. Potassium has been applied according to four modalities of treatments (T0; T1; T2 and T3) made in 2nd, 4, 6 and 7th months (respectively) after plantation. The incidence of internal browning (IB), the phenolic content, sugars and ascorbic acid have been determined after post-harvest conservation of fruit. The activity of phenolic biosynthesis enzymes (PAL and TAL) and oxidation enzymes (PPO and POD) were evaluated. The results showed that BI intensity in pineapple fruit decreases with the potassium amount applied in field. This IB drop was correlated with the content of reducing sugars, total phenols, activity of PAL and the PPO. No symptom of IB was observed on pineapple fruits under treatment T2 (34 g of K2O/plant). Potassium has a depressive effect on phenolic biosynthesis. In effect, it inhibits the IB in the both varieties of pineapple studied that are Smooth Cayenne and MD2.

The improvement of pineapple (Ananas comosus var. Smooth Cayenne) by means of in vitro culture is less studied in Côte d'Ivoire despite the importance of this plant for this country’s economy. Our work consisted in highlighting nature and concentration effects of carbohydrates on the proliferation of calli in pineapple as a prelude to efficient embryogenesis. Callus proliferation was carried out from the base of pineapple vitroplants leaves. Thirty (30) explants were cultured on the tested culture medium. MS medium (micro- and macro elements of Murashige and Skoog) supplemented with vitamin Gamborg B5 was used as base medium to which were added 0.05 mg/L BAP, 3 mg/L picloram, 2 mg/L glycine, 1,000 mg/L glutamine, 100 mg/L casein hydrolyzate and 30 g/L carbohydrate. Sucrose was tested at different concentrations (20, 25, 30, 35 and 40 g/L). The results revealed that callus proliferation is strongly influenced (p ˂ 0.0001) by nature and concentration of carbohydrate. Sucrose with the highest dry matter content (61.34 mg) has a higher callogenic potential than the other studied carbohydrates. The concentration of 30 g/L sucrose significantly improved the calli proliferation in pineapple. Galactose and maltose were less favorable to proliferation.

The cultivation of pineapple contributes 1.6% of the gross Ivorian national product (GDP). However, this crop is facing a severe production crisis due to the aging of the orchards. Revising this sector requires the rejuvenation of orchards with healthy and improved planting material. This work was conducted to study the conditions for the efficient in vitro production of restorative pineapple planting material by somatic embryogenesis. The effects of seven culture media consisting of a different combination of nitrogen sources (casein hydrolyzate, glutamine, and glycine), cytokinins (kinetin or BAP), and auxins (2,4-D or picloram) were tested on somatic embryos induction and maturation in pineapple. Results of the study revealed that EIM1 (EIM added with 3 mg.L-1 picloram, 0.05 mg.L-1BAP, 2 mg.L-1 glycine, 1000 mg.L-1glutamine, 100 mg.L-1casein hydrolyzate) and EIM5 (EIM added with 2 mg.L-1glycine, 100 mg.L-1casein hydrolyzate, 0.2 mg.L-1kinetin) media induced the highest numbers of embryogenic cells, i.e., 154 and 149 cells respectively. Further, the EIM5 medium was more embryogenic, with the most significant number of mature embryos (66 mature embryos), and allowed the observation of all embryonic maturation stages. Embryogenic cell induction in pineapple is thought to be controlled by a low NH4+/NO3- ratio in interactions with phytohormones. In the presence of 2,4-D, embryogenic cell maturation was improved by kinetin addition to the culture medium containing glycine and casein hydrolyzate.

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 was to 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