Comparative evaluation of enzyme activities and phenol content of Irish potato (Solanum tuberosum) grown under EM and IMO manures Bokashi

Irish potato (Solanum tuberosum) is one of the world’s most consumed staple. In order to develop natural fertilizers to increase Irish potato yield, we assessed the use of manures (EM Bokashi and IMO Bokashi, which are cocktail of beneficial bacteria; used as a soil remediation and health measure in many organic farms) on potato tubers in Bambili village in the North West Region of Cameroon, through evaluating biochemical parameters such as the phenol content, and the activities of peroxidase (POX), polyphenol oxidase (PPO) and pectinmethyl esterase (PME) enzymes. In this respect, a land of 18 x 8 m2 with six plots of 18 beds each was used to cultivate the plant. The plant length and weight of tubers were quantified in the field. Relative to controls (55.96 ± 25.83 cm), both EM and IMO Bokashi produced longer plants (73.85 ± 27.74 cm and 65.25 ± 23.45 cm respectively) but between experimental plants, EM Bokashi led to heavier tuber weights (234 ± 132 g) compared to IMO Bokashi. Interestingly, biochemical analyses showed the highest phenolic content and PME activity in plants treated with EM Bokashi. All treatments significantly increased POX activity while they decreased PPO activity. In addition, significant and positive correlations (P < 0.01) were observed between stem length and PME activity independent of treatment. Plant treated with IMO Bokashi had significant and positive correlations between stem length and weight on the one hand and between stem length and biochemical parameters on the other hand. These findings showed that EM and IMO Bokashi treatments increased the phenol content, PME, PPO and POX activities during the growth of S. tuberosum and can thus be used to improve its growth and productivity.Keywords: Solanum tuberosum, phenol content, biochemical markers, Bokashi manures, productivit

Germination of Cola anomala (K. Shum.) Shott and Endl seeds: effects of provenance, substrate and dehydration

As a step in the process of Cola anomala domestication, investigations were undertaken on germination requirements and desiccation tolerance of its seeds. Three seed provenances (Bamenda, Bayangam and Dschang), three substrates (forest top soil, river sand and a mixture of forest top soil and river sand) and two photoperiods (12 hours/day and, continuous darkness) were investigated for their effects on seed germination. To evaluate their desiccation tolerance, fresh seeds were dried at room temperature for 16 days during which seed moisture content, seed germination percentage and electrical conductivity of seed leachate were monitored at two-day intervals. Results showed that germination percentages were significantly (P < 0.05) higher both on forest top soil alone (86.04 ± 4.8%), and on a mixture of forest top soil and river sand (83.56 ± 4.5%), than on river sand alone (69.96 ± 4.7%). Seeds from Bamenda showed a higher germination percentage (91.4 ± 4.7%) than those from either Bayangam (77.36 ± 4.7%) or Dschang (70.8 ± 4.8%). The desiccation tolerance test revealed that as response to drying, the mean germination percentage was first slightly reduced as moisture was lost, then declined considerably at moisture content below 50.28%. Total germination failure was observed when seed moisture reached 32.24%. Electrical conductivity of seed leachate exhibited a strong correlation with loss of viability as well as with desiccation. It is concluded that there is a provenance-related variation in C. anomala seed germination. The best substrate for germination is forest top soil supplemented or not with river sand in a 1/1 (v/v) ratio. C. anomala seeds are desiccation-sensitive and their storage behaviour is recalcitrant.Keywords: Desiccation tolerance, critical moisture, lethal moisture, electrical conductivity, electrolyte leakage, storage behaviour

Assessing relationship between phenolic compounds and resistance tPhytophthora megakarya using two cocoa (Theobroma cacao) families

Black pod disease is an important fungal infection in cocoa (Theobroma cacao L.) which causes high production losses. In Cameroon, these losses reached 80% of cocoa production depending on ecological zones. In order to contribute to the efficiency of selection methods used in resistance or tolerance to black pod disease with the aim of improving on cocoa farming, the content of phenolic compounds was analyzed on the genotypes of two hybrid families (F79:♀T79/467x♂SNK13 and F13:♀SNK13x♂T79/467) of cocoa which are different in productivity and vulnerability to black pod disease. After artificial inoculation of the pods by mycelium of Phytophthora megakarya, the content of the phenolic compounds significantly increased in all genotypes of the two families. The heterosis effect of each family revealed a higher variability within both families. These results alike showed that productive and tolerant genotypes (F1307, 1314, F7902 and F7928) have a high phenols content and positive heterosis meanwhile the less tolerant and productive genotypes (F1321, F1326, F7904 and F7911) have a weak content and negative heterosisKeywords: Cocoa, disease, tolerance, heterosis effect, phenolic compounds, hybrid progeniesAfrican Journal of Biotechnology Vol 13(29) 2956-296