To investigate the possible role of arbuscular mycrrhizal fungi (AMF) in alleviating the negative effects of salinity on Stevia rebaudiana (Bert.), the regenerated plantlets in tissue culture was transferred to pots in greenhouse and inoculated with Glomus intraradices. Salinity caused a significant decrease in chlorophyll content, photosynthesis efficiency and enhanced the electrolyte leakage. The use of AMF in salt –affected plants resulted in improved all above mentioned characteristics. Hydrogen peroxide and malondialdehyde (MDA) contents increased in salt stressed plants while a reduction was observed due to AMF inoculation. CAT activity showed a significant increase up to 2 g/l and then followed by decline at 5 g/l NaCl in both AMF and non-AMF treated stevia, however, AMF inoculated plants maintained lower CAT activity at all salinity levels (2 and 5 g/l). Enhanced POX activities in salt- treated stevia plants were decreased by inoculation of plants with AMF. The addition of NaCl to stevia plants also resulted in an enhanced activity of SOD whilst, AMF plants maintained higher SOD activity at all salinity levels than those of non-AMF inoculated plants. AMF inoculation was capable of alleviating the damage caused by salinity on stevia plants by reducing oxidative stress and improving photosynthesis efficiency.
Yam (Dioscorea sp.) is a popular tuber in Cameroon, where it is grown for both food and income. One of the most challenging aspects of the long-term storage of yam tubers is post-harvest spoilage, often caused by fungi. The use of post-harvest chemicals on yam tubers is not a matter of course. The present study evaluated the efficacy of aqueous extract and powder of Zingiber officinale against fungi associated with the storage rot of yam. The fungi were isolated from two yam cultivars, “Calabar” and “Ghana”, from three localities in Cameroon. The antifungal activity of the aqueous extract and ginger powder was studied in vivo on slices of yam tubers. The results obtained showed that eight fungi were associated with yam tubers and exhibited typical rotting symptoms. The most prevalent and virulent fungus was Penicillium sp., which caused decay volumes of 12.76 cm3 and 8.74 cm3 for “Calabar” and “Ghana” cultivars, respectively. Fungal spoilage was greatly reduced by the application of aqueous extract and ginger powder. The aqueous extract tested at the 30% dose was more effective with up to 80% inhibition. However, the ginger powder was more effective against Penicillium sp., Aspergillus niger, and Colletotrichum sp. associated with rot in the variety “Ghana” with total inhibition (100%). Therefore, the aqueous extracts and powder of Zingiber officinale can be used as a bio fungicide to improve the shelf life of yam tubers.
Entomopathogens are microorganisms that pathogenic to insect pest. Several species of naturally occurring viz; fungi, bacteria, viruses and nematodes, infect a variety of insect pests and play an important role in agricultural crops controlling insect pest management. This kind of biopesticide has many advantages and alternative to chemical insecticides, highly specific, safe, and environmentally sustainable. Pest problems are an almost inevitable part of agriculture. They occur largely because agricultural systems are simplified and modifications of natural ecosystems. Viruses, bacteria are host specific and fungi generally have broader host range and can infect both underground and aboveground pests, soil-dwelling nature nematodes are more suitable for managing soil pests. Growing crops in monoculture provides concentrated food resource that allows pest populations to achieve higher densities in natural environments. Some of the most important problems occur when pests develop resistance to chemical pesticides. These cause highly significant damage to crops, there are also threats from emerging new strains of pests. Crops cultivation can make the physico-chemical environment more favourable for pest activity. Agricultural pests are reducing the yield and quality of produce by feeding on crops, transmitting diseases. Agricultural production significantly loss crop yields, suggest that improvements in pest management are significant forward for improving yields. Crop growers are under immense pressure to reduce the use of chemical pesticides without sacrificing yields, but at the same time manage of pests is becoming difficult due to pesticide resistance and the decreasing availability of products. Alternative methods are needed urgently. These need to be used as part of Integrated Pest Management safety and environmental impact.
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