Pennisetum purpureum

Pennisetum purpureum
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
(unranked):	Commelinids
Order:	Poales
Family:	Poaceae
Tribe:	Paniceae
Genus:	Pennisetum
Species:	P. purpureum
Binomial name
Pennisetum purpureum Schumach. 1827

Pennisetum purpureum, also known as Napier grass, elephant grass or Uganda grass, is a species of perennial tropical grass native to the African grasslands. It has low water and nutrient requirements, and therefore can make use of otherwise uncultivated lands. Historically, this wild species has been used primarily for grazing; recently, however, it has been incorporated into a pest management strategy. This technique involves the desired crop being planted alongside a 'push' plant, which repels pests, in combination with a 'pull' crop around the perimeter of the plot, which draw insects out of the plot. Napier grass has shown potential at attracting stemborer moths (a main cause of yield loss in Africa) away from maize and hence is the "pull" crop. This strategy is much more sustainable, serves more purposes and is more affordable for farmers than insecticide use. In addition to this, Napier grasses improve soil fertility, and protect arid land from soil erosion. It is also utilized for firebreaks, windbreaks, in paper pulp production and most recently to produce bio-oil, biogas and charcoal.

Pennisetum purpureum is a monocot C4 perennial grass in the Poaceae family. It is tall and forms in robust bamboo-like clumps. It is a heterozygous plant, but seeds rarely fully form; more often it reproduces vegetatively through stolons which are horizontal shoots above the soil that extend from the parent plant to offspring. This species has high biomass production, at about 40 tons/ha/year and can be harvested 4-6 times per year. Additionally it requires low water and nutrient inputs.

Napier can be propagated through seeds, however as seed production is inconsistent, collection is difficult. Alternatively, it can be planted through stem cuttings of the stolons. The cuttings can be planted by inserting them along furrows 75 cm apart, both along and between rows.

Stemborers (Busseola fusca and Chilo partellus) are the cause of 10% of total yield loss in Southern and Eastern Africa and on average 14-15% in sub-Saharan Africa. The larvae cause immense damage to maize and sorghum by burrowing into their stems and eating from within. This not only makes them difficult to detect and remove but also damages the vascular tissue necessary for plant growth. Insecticide effectiveness is low against stemborers, as larvae are protected by protective cell wall layers around the stem. Insecticides are also expensive for poor farmers and can build chemical resistance by the pests. In addition, chemicals are carried into final food products. Instead of trying to prevent the occurrence of pests, the push-pull strategy (also known as stimuli-deterrent) aims to guide their inevitable biological evolution to prevent damage to valued crops. The method proposes that sorghum or corn be intercropped with Desmodium (the "push" plant), which repels the moths as they look to lay their eggs. Desmodium also provides a ground cover and is nitrogen fixing, which improves soil fertility while decreasing labour involved with weeding. This deterrent is used in combination with Napier grass planted around the perimeter of the plot. A study of Kenyan farmers using the push-pull strategy reported an 89% reduction in Striga (a parasitic weed), an 83% increase in soil fertility, and 52% effectiveness in stemborer control. Considering that striga, stemborers, and low soil fertility together cause yield losses of an estimated 7 billion US dollars or enough to feed 27 million people, the implementation of this technique could significantly reduce food insecurity.

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Wikipedia