Effet des poudres de coquilles d’huitre sur la croissance et la résistance a la cercosporiose noire des semences pif de bananier plantain var. batard.

Abstract

Banana-plantain is one of the cash crops that greatly contribute to food security of the Cameroonian population. It however, faces many difficulties, including, seed insufficiency particularly those of good quality and Black Sigatoka caused by Mycosphaerella fijiensis. Chemical control, typically used to control this disease is very costly and has adverse effects on human health and the environment. An alternative to these problems would be a combination of biological control agent with the method of plants from stem fragment (PIF) for the production of quality seeds. The aim of our work was to evaluate the effect of the oyster shell (OS) powder on the growth of banana-plantain seedlings var. Bâtard produced by the PIF method and their resistance to Black Sigatoka. The effect of oyster shells was first evaluated on the growth of seedlings, then on the resistance to Black Sigatoka. Our results show that the powder of oyster shells (10%) increases the speed of germination of banana-plantain explants on average from 33 to 67% and the cumulative number of seedlings issued from 40 to 55%. The 10% treatment improves the average growth rate of the seedlings by 12% in diameter, 27% vertically and 41% leaf area. Necrosis surface due to Black Sigatoka was significantly (P <0.05) lesser for seedlings treated compared to controls. Indeed, the treated seedlings surface necrotic average values of about 0.2 cm2 on day 6 and 4.4 cm2 at day 14 compared to those of control, 1.8 cm2 and 23.3 cm2 the same dates respectively. The growth and the degree of resistance were correlated with increased synthesis of phenolic compounds and total protein in seedlings before and after infection. The mean levels of phenolic compounds are 1.05 mgEqCat/GMF and 0.84 mgEqCat/GMF respectively for the treated plants and untreated before infection, against 2.45 mgEqCat / GMF 1.85 mgEqCat/FMG for the same plants after infection. Total protein levels were 2.90 mg EqBSA/GMF EqBSA and 1.13 mg/GMF respectively for the treated plants and untreated before infection, against 7.20 mg EqBSA/GMF and 6.33 mg EqBSA/GMF for the same plants after infection. These results suggest that the oyster shells could be used as bio-fertilizers and bio-fungicides in the mass production of PIF quality seeds and control of Black Sigatoka in the nursery.