Cultivar and Soil Fertilizer Treatment Affect Seed Production of Sweet Yellow Yam ( Dioscorea dumetorum) on Highly Acidic Soils of the Western Highlands Region of Cameroon

Abstract

The popularization of Dioscorea dumetorum (Dioscoreaceae), a nutritious yam species is still marginal due to constraints such as the low interest of research, poor cultural practices, insufficient and expensive seeds, pests, and diseases. The latter pushes producers to use about 50% of their harvest as seed for the next planting season. The lack of a specific fertilizer formulation for yam production on the oxysols of Cameroon is another constraint. This study was aimed at enhancing the availability of quality seeds through the characterization of five yam accessions. One experiment was performed to determine the effect of cultivar and origin of tuber sets on their germination rate. The second concerned the evaluation of cultivars and soil treatment effects on agronomic parameters of yam seedlings. Yam cultivars were subjected to nine fertilizer formulations as follows: T0: no fertilizer; T1: mycorrhizal fungi (MF) + 150 g manure + peanut waste; T2: 25 g chemical fertilizer (20.10.10); T3: MF + peanut waste; T4: 16 g chemical fertilizer (12.6.20); T5: 25 g (20.10.10) +100 g CaO + 150 g manure; T6: 100 g CaO + 150 g manure; T7: 20 g tropicote + 2 g DAP (Diammonium phosphate, a reference starter fertilizer coded N18P46) + 100 g CaO + 150 g manure; and T8: mycorrhiza. These treatments were tested in a factorial design. Results show that Ibo sweet 3 and Mabondji sweet white 1 yam accessions were less affected by anthracnose disease on the aerial parts. Guzang 1 showed the best germination rate and yield, making it appropriate for cultivation in the region. Soil treatments, T2, T5, T7 and T8 significantly increased the yield of yam cultivars. Mycorrhiza treatment alone gave a better response to seed weight, indicating the interest of this biofertilizer as a solution for good seedling production. These fertilizer treatments can be recommended to farmers for more seed production with optimum seed weight (300 g).