Response of cocoa seedlings (Theobroma cacao L.) variety FSV-094 to mycorrhizal inoculation under nursery conditions

Abstract

A greenhouse experiment was carried out to evaluate the mycorrhizal response of seedlings of cocoa (Theobroma cacao variedad FSV-094) to the application of different mycorrhizal inoculum. A complete randomized experimental design was used, with four treatments: three commercial mycorrhizal multispore inoculum, Ab (Glomus spp, Scuttellospora spp y Entrophospora spp), Bs (Glomus spp, Acaulospora spp, Entrophospora spp, y Scutellospora spp) y Bl (Rhizophagus irregularis, R. clarus, R. aggregatus, R. proliferum y Claroideoglomus etunicatum), and the negative control (without inoculation), each treatment was established in the same soil that was adjusted 0.02 mg L-1 of phosphorus (P). Shoot and root dry weight (SDW & RDW), mycorrhizal colonization, leaf P content, and mycorrhizal response were measured. The results indicated that all the inoculum showed colonization, the best treatments were Ab and Bs with values of 27 and 28% respectively. Although there were no significant differences, the Ab and Bs treatments always had higher values in terms of SDW (3,4 y 3,7 g) and leaf P (0,25 y 0,2%). Regarding to mycorrhizal response, it was found that when inoculated with Bs and Ab the response was moderate (25 - 50%), and with Bl marginal (≤ 24%). The use of commercial AMF can lead to a differential response to T. cacao variety FSV-094. Therefore, it is suggested to carry out an evaluation of the mycorrhizal inoculum in relation to the genotype before massively using it to produce cocoa seedlings under greenhouse.

Keywords

• arbuscular mycorrhizal fungi
• mycorrhizal response
• phosphorus