Potential Biostimulant Effect of Clam Shells on Growth Promotion of Plantain PIF Seedlings (<i>var</i>. Big Ebanga &Batard) and Relation to Black Sigatoka Disease Susceptibility

Plantain contributes significantly to income generation and food security for millions of people in the world. However, it faces problems of seedlings quantity, quality and availability. The innovation of the “plants issus de fragments de tiges” (PIF) technique could be a solution to these problems for small holders’ farmers. The aim of this research is to evaluate the effect of clam shells through amendment of Batard and Big Ebanga PIF substrate, on the growth promotion of seedlings and their protection against black Sigatoka disease (BSD). Plantain PIF seedlings of the two varieties were grown in a substrate amended with 1% concentration of the clam shells powder in the presence of negative control in the sterile and non-sterile conditions. Agromorphological characteristics, susceptibility level to BSD, total proteins and polyphenols content were assessed. Because of the presence of clam shells in the substrates, explants germinated quickly, generated high number of shoots, grew taller by 32%, with a diameter of pseudo stems of 30%, and area of leaves of 18% compared to control. In addition, the seedlings were less susceptible to BSD by 73% compared to those of controls. The treatment seems to allow the accumulation of larger amounts of total proteins and polyphenols before inoculation and after inoculation that could participate in the growth promotion and the reduction of plant’s susceptibility level. Clam shells treatment acts as a biofertilizer/biopesticide and could be helpful to boost production of plantain seedlings, the use of the by-products of fishing in agriculture and helps alleviate poverty of small holders’ farmers.

Plantain Bananas PIF Seedlings Treatment with Liquid Extracts of <i>Tithonia diversifolia</i>Induces Resistance to Black Sigatoka Disease

Plantain bananas culture encounters the problems of seedlings quantity and quality unavailability. Black Sigatoka Disease (BSD) is one of the main pathological constraints of banana that can severely reduce the photosynthetic leaf area, leading to the losses of production of about 50% in banana plantation. The use of liquid extracts of Tithonia diversifolia could potentially induced the resistance of the PIF seedlings to BSD during the vegetative stages in the nursery. The aim of this work was to evaluate the effect of Tithonia diversifolia liquid extracts against the development of BSD on the PIF plantain bananas seedlings. The explants in the greenhouse and the seedlings in the shade were watered with liquid extracts of T. diversifolia during the process of PIF seedling production in sterile and non-sterile conditions. The treated seedlings show a more effective enhancement of seedlings quality parameters and also induce resistance against BSD. The vegetative stages parameters (the number of shoots, the diameter and the height of shoots, the foliar area, the length and weight roots) were improved in treated seedlings compared to controls ones. The treated seedlings showed maximum protection against BSD of up to 87% compared to controls. They also exhibited an increase in the accumulation of total proteins and total phenolics, as well as the activity of defense-related enzymes (peroxidase, polyphenol oxidase and glucanase). The treatment seems to acts as a vital stimulator and could therefore be a useful tool for small holder farmers favouring an eco-friendly agriculture using fewer synthetic inputs.

<i>Tithonia diversifolia</i>Mulch Stimulates the Growth of Plantain PIF Seedlings and Induces a Less Susceptibility to <i>Mycosphaerella fijiensis</i>in the Nursery

Plantain is an important crop that serves as a staple food and contributes significantly to income generation for millions of people in tropical and sub-Saharan Africa. Its cultivation faces the main constraint of seedlings unavailability in quantity and quality, essential for the creation of new plantations. The advent and popularization of the plantlets from stem bits (PIF) in the 2000s raised hopes for solving this problem. However, after about ten years, the PIF has shown some problems limiting its adoption and should be improved for more efficiency. The amendment of PIF substrate production with Tithonia diversifolia could be an alternative to seedlings’ unavailability. This study aims to evaluate the potential stimulative effect of T. diversifolia mulch on plantain PIF seedlings growth and protection against black Sigatoka disease (BSD)caused by Mycosphaerella fijiensis. The parameters of vegetative growth stages and biomarkers accumulation were assessed in sterilized substrate and non-sterilized substrate conditions. T. diversifolia mulch treatment increases the germination rate, the number of shoots, the height and the diameter of shoots, the leaf area as well as the seedlings roots, but it also protects the seedlings against BSD up to about 81% compared to the control seedlings. It also enhances the accumulation of biomarkers such as proteins, polyphenols content and defense-related enzymes (peroxidase, polyphenol oxidase and glucanase). T. diversifolia mulch seems to act in PIF seedlings production as a vital stimulator. It can therefore be taken as a tool for a more sustainable and resilient agriculture, and for poverty alleviation of poor small holder farmers.

Antioxidant properties of cell wall polysaccharides of Stevia rebaudiana leaves

Objective:To examine the total phenolic and protein contents,and the antioxidant activities of cell wall polysaccharide fractions of Stevia rebaudiana leaves.Methods:Three different polysaccharide-enriched fractions,namely FPE(extract with 50 mmol/L ethylene diamine tetra acetic acid),FPK(extract with 0.05 mol/L KOH)and FH(extract with 4 mol/L KOH)were extracted from Stevia rebaudiana leaves.The antioxidant activity of these fractions was evaluated based on their ability to scavenge DPPH(1,1-diphenyl-2-picryl hydrazyl)free radical,to reduce ferric power,to chelate ferrous ion and to protect human DNA.Results:The results indicated that protein content was found to be higher in FPK polysaccharide enriched fraction(47.48μg per mg of FPK).Furthermore,the phenolic compound analysis according to the Folin-Ciocalteu method was higher in FPK(17.71μg ferulic acid).The DPPH maximal inhibition percentage of the three polysaccharide-enriched fractions at 400μg/mL was 27.66%,59.90%and 23.21%respectively for FPE,FPK and FH.All the polysaccharide fractions exhibited a ferric reducing power except the FH one.The three fractions also exhibited lipid peroxidation inhibition,and they completely reverted the DNA damage induced by H_(2)O_(2)/FeCl_(2).FPK showed the strongest scavenging activity against the DPPH radical,the best chelating ability and lipid peroxidation inhibition.Conclusions:Stevia cell wall polysaccharide fractions are potent protective agents against oxidative stress.The analysis revealed major differences in the antioxidant activity in the three polysaccharides fractions.However,the 0.05 mol/L KOH pectin fraction(FPK)showed better antioxidant activity.