Effet des mycorhizes sur la croissance du macabo (Xanthosoma sagittifolium L.Schott), cultivar blanc.

Abstract

This dissertation is on Xanthosoma sagittifolium which is a plant from tropical America. It is grown for its tuber, its abundance in starch and some nutritive elements it contain. The main objective of this work is to evaluate the effect of mycorrhizes (Gigaspora margarita; Acaulospora tuberculata + Gigaspora margarita and Acaulospora tuberculata + Gigaspora margarita + Gigaspora margarita) in cocoyam growth. The morphological analyses have shown that mycorrhized plants and those who received additional contribution in carbon have the foliaceous surfaces, height and an important number of roots than reference plants. It presents respectively maxima of 60,41±0,84 cm2 for plants treated with Acaulospora tuberculata + Gigaspora margarita; 18,35 ±0,95 cm for plants treated with Acaulospora tuberculata + Gigaspora margarita + source of carbon, and 30 ± 2 for plants treated with Gigaspora margarita. The historical analysis revel that toadstool Gigaspora margarita colonise quickly the explants of cocoyam with and important rate of mycorrhization of 81%. And when this rate is associated to Acaulospora tuberculata +Gigaspora. margarita, the intensity of mycorrhization is 47,1. The biochemical analysis show that the maximal content in chlorophyll a and in chlorophyll b for plants treated with G. margarita + source of carbon in J30, 0,36 ± 0.00 mg/g of MF and 0,54 ± 0.00 mg/g of MF. The maximal concentrations in amino acid are 13,32 ± 0,75 mg/g of MF for plants treated with Acaulospora tuberculata + Gigaspora margarita + Gigaspora margarita in J60 and 19,65 ± 0,73mg/g of MF for plants treated with Acaulospora tuberculata + Gigaspora margarita in J120 in leaves and roots respectively. The maximal concentrations in proline are 4,02 ± 0,62 mg/g of MF for plants treated with Acaulospora tuberculata + Gigaspora margarita and 5,37 ± 0,04mg/g of MF for plants treated with Acaulospora tuberculata+Gigaspora margarita + source of carbon in J120 in leaves and rhizomes respectively. The maximal concentrations in soluble sugars are 6,13± 0,35 mg/g of MF for plants treated with Acaulospora tuberculata + Gigaspora margarita + Gigaspora margarita + source of carbon in J60 and 6,67 ±0,17mg/g of MF for Reference + source of carbon in J30 contained leaves and rhizomes respectively.