Thunes K.H.,PO Box 115 As |
Ratnadass A.,Institute for the Semi Arid Tropics |
Ratnadass A.,HortSys Unit |
Nikiema A.,Institute for the Semi Arid Tropics |
And 2 more authors.
International Journal of Tropical Insect Science | Year: 2016
Herbivory by insects and mites on physic nut (Jatropha curcas L.) seedlings was investigated and compared with irrigation in the semi-arid Sahelian Niger, utilizing a randomized complete block design experiment. Three water treatment protocols were applied and the types of damage were recorded. Less than 5% of the seedlings died during the 10-month trial period with sap suckers causing the most damage on the surviving plants. Plants with high production of biomass and leaf cover (foliage) were most strongly positively correlated with irrigation and were also the plants that endured the highest degree of herbivory. The low dieback may indicate that defence mechanisms counteract seedling herbivory and that drought-stressed plants invest more in their defence mechanism system than vital plants. © 2016 icipe.
Michels T.,Hortsys Unit |
Bisson A.,Hortsys Unit |
Ralaidovy V.,Hortsys Unit |
Rabemananjar H.,Hortsys Unit |
And 2 more authors.
Acta Horticulturae | Year: 2011
Cloves are one of the main Malagasy agricultural exports and their production is based on family farming. Helping farmers to develop their cropping systems towards more sustainable systems calls for a comprehensive picture of the diversity of their practices. This study set out to fill knowledge gaps on this point. Three scales were considered, i.e. plot structure, cropping system and farming system, in order to identify the principal characteristics, functions, and constraints of clove-based farming systems. We applied a double typology: one focused on cropping systems and the other on farm functioning. A study of practices showed three types of cropping systems and a main tendency to associate cloves with other species, both annual and perennial, in agroforestry systems (AFS). In wet tropical areas, AFS are often the only means of subsistence for poor farmers, but also potential vectors of economic and social development. A study of complex AFS structures on a restricted sample showed that cloves, which accounted for nearly 70% of perennial species in the plot, are mainly associated with fruit species, structural timber and firewood, and sometimes coffee. The global farm level approach made it possible to identify highly contrasting situations: from young and dynamic farms geared toward food production or livestock farming, to old, poor and only slightly diversified farms.