Effectiveness of mycorrhizal inoculants on sweet potato (Ipomoea batata) in Eutric Cambisol soils of Cuba

Abstract

Introduction. The effective use of mycorrhizal inoculants is a challenge for Cuban agriculture. Sweet potato is an important crop for human and animal nutrition, being a mycorrhizal dependent crop with a successful breeding program. Objectives. To know if all sweet potato cultivars respond to inoculation and if its effectiveness varies with cultivars and growing seasons. Materials and methods. Two experiments were carried out during 2010 - 2012 on Eutric Cambisol soils from Villa Clara, Cuba. One at each planting time and repeated twice. The response of 17 cultivars to three inoculants application in the presence of a half dose of fertilization, and three non-inoculated treatments with fertilization levels of 0, 50, and 100 % of nitrogen, phosphorus, and potassium dose (100 % NPK) was evaluated, using a split plot design. Edible root yields, mycorrhizal colonization frequency and spores were evaluated as response variables. Results. Cultivars responded positively to inoculation and fertilization, showing differences in their yields, however, highest yields were always found when inoculated with Rhizoglomus irregulare/ INCAM-11, which were higher (p<0.05) than those obtained when receiving only 50 % NPK dose. In the rainy season with higher yields, the differentiation between inoculants was higher and in thirteen and nine of the cultivars, the yields obtained with INCAM-11 were higher (p<0.05) than those obtained with Glomus cubense/ INCAM-4 and with 100 % NPK respectively. In the low rainy season, no significant differences were found between yields obtained by inoculating INCAM-11 or INCAM-4 or applying 100 % NPK. In both seasons, inoculation with Funneliformis mosseae/ INCAM-2 was always lower. Colonization frequencies and spore production were always higher (p<0.05) when inoculating INCAM-11. Conclusion. Under these soil conditions, INCAM-11 inoculation presented better effectivity for all cultivars and planting seasons originating the highest yields and indicators of mycorrhizal performance.