No abstract

Mineral nutrition effect on anthracnose caused by Colletotrichum gloeosporioides, tuber rot by Botryodiplodia theobromae and yield in Dioscorea rotundata var. Iseosi was investigated in this study. The field plot used had been monoropped to Dioscorea species in the two previous consecutive years with only calcium nitrate fertilizer. But nitrogen and calcium in the plot soil were still below the critical (2% and 0.6 cmol kg -1 respectively) determined for optimum yam production (South West Nigeria). The field design was RCBD with 3 treatments of 0, 0.6, 1.2ml/l -1 Bounty fertilizer applied at 3 MAP, and three replicates. Bounty fertilizer favoured higher concentration of the phytoanticipins (with antimicrobial activity) flavonoid, lignin and tannin over the control. Leaf N and Mg had significant correlation with leaf flavonoid content (r = 0.7634, 0.6786). Leaf flavonoid had significant correlation with leaf lignin content, r = 0.7189. Leaf lignin in turn had significant correlation with leaf tannin content, r = 0.7556. Leaf Sulphur correlated significantly with leaf flavonoid and leaf phosphorus, r = 0.7218 and 0.8467 respectively. Bounty fertilizer also favoured higher leaf magnesium 234.73 and 230.27mg/100gdm (0.60ml/l -1 and 1.20ml/l -1 ) than the control, 182.40mg/100gdm. Leaf nitrogen, phosphorus and sulphur increased with bounty fertilizer treatment, then the control. Only leaf potassium was higher in the control (116.72mg/100gdm) than in the Bounty-fertilized plants with 87.31 and 87.53mg/100gdm in the 0.60mll -1 and 1.20mll -1 treatments.The following correlations were also significant respectively: Leaf N and Leaf P, S, r = 0.8484 and 0.9836 respectively.Leaf Ca and leaf Mg, r = 0.9192 Anthraconse incidence did not increase after the 3 MAP bounty fertilizer soil amendment. It was 11%, 6% and 0% in the control, 0.60ml/l -1 and 1.20ml/l -1 treatments respectively at 5 MAPS. It reduced to 5.6% (control and 0.60ml/l -1 treatment) and remained 0% in the 1.20ml/l -1 treatment at 6MAP. Severity of anthracnose was 1, category of resistant, both at 5 MAP and 6 MAPS across all the three treatments. The interplay/ enhancement of leaf minerals with the three phytochemicals/anticipants, as well as the latter with one another should be responsible for the low disease incidence and resistant severity status of variety Oniyere. Mean tuber weight loss after inoculation and incubation with B. theobromae for 2 weeks was 0% and infection range over the three treatments was low, that is 1.21 to 2.95% with no significant differences. Mean tuber weight per plant was in the range 0.88kg to 1.35kg with no significant differences between treatments. The 1.20ml/l -1 bounty fertilizer treatment gave equivalent yield of 13.46 tons ha -1 . Bounty fertilizer at 0.60ml/l -1 or 1.20ml/l -1 is recommended for local varieties of white guinea yam in South West Nigeria especially where monocropping is desired.

This study was carried out to relate infection and weight loss by Botryodiplodia theobromae Pat, in Colocasia esculenta L. corms with their phenol and/or calcium content. Corms were sourced from two major root and tuber markets in Osiele and Kila, in Odeda Local Government Area of Ogun State, Nigeria. The infection and weight loss experiment was in CRD (complete randomized design), with two treatments (the two markets) and seven replicates. Corms were inoculated with a 10-day old pure culture of B. theobromae and incubated for 10 days, after which infection and weight was determined. The infected corms were then analysed for phenol, calcium, nitrogen, phosphorus, potassium, magnesium, iron and sulphur content. Corms from Kila had infection and weight loss 41% and 37% respectively lower than corms from Osiele.Phenol and calcium content of the corms from Kila were 89.20 mg/100gdm and 19.8 mg/100gdm respectively, significantly higher than those of the Osiele corms which were 81.59 mg/100gdm and 18.9 mg/100gdm respectively. High phenol with its antimicrobial activity as well as higher calcium conferring higher structural integrity against deterioration are adduced as the reason for lower infection and weight loss in the corms from Kila. The corms from Kila were also superior in terms of higher levels of six other nutrient minerals namely N,

No abstract

Agriculture, Abeokuta, Ogun State, Nigeria. The tubers had been fertilized in the yam project plot with bounty fertilizer containing eight minerals namely Calcium 7% w/w, Magnesium oxide 0.50% w/w, manganese 1% w/w, Iron 2% w/w, Zinc 2% w/w, Copper 0.50% w/w, Boron 0.0025% w/w, and Nitrogen 15% w/w. Rate of fertilization was 0.60 ml l -1 and 1.20 ml l -1 of Bounty fertilizer. Another set of the four varieties were sourced from farmers plots within Ogun State (South West region of Nigeria).