Evaluation des performances de la production de graines par tamisage manuel du sol chez trois variétés de Stylosanthes guianensis (Aublet) Swartz, dans les conditions du Plateau des Batéké (RDC)

Performance Assessment of the Production of Seeds by Manual Sieving of the Soil of Three Varieties of Stylosanthes guianensis (Aublet) Swartz under the Conditions of the Batéké Plateau (DRC). In manual agriculture with low resources level, Stylosanthes guianensis is one of the most interesting cover crop for developing direct seeding mulch-based cropping systems. To promote its cultivation in the DRC, the performances of a seed production method by sieving of the soil were evaluated for three varieties of Stylo (a local ecotype, CIAT 184 variety, and 202cc variety) in two sites of the Batéké plateau characterized by contrasted fertility levels. The results obtained demonstrate the interest of the seed multiplication method tested, both in quantities and quality of the produced seeds. The production cost of one kg of seeds varies with the soil fertility, the planting date, and the cultivar. Among the three compared varieties, CIAT 184 variety produced the highest quantity of seeds. If sown at the beginning of the long rainy season, after a long fallow, in one of the most fertile soils of the plateau, this cultivar can produce 600 kg ha-1 seed in the first year of cultivation with a production cost of USD 1.31 kg-1, equivalent to less than 0.5 man.day.kg-1

Performances de trois variétés de manioc (Manihot esculenta Crantz) cultivées en association avec Stylosanthes guianensis (Aublet) Swartz dans les conditions du plateau des Batéké (ville-province de Kinshasa, RDC)

Performance of Three Varieties of Cassava (Manihot esculenta Crantz) Grown in Association with Stylosanthes guianensis (Aublet) Swartz in the Conditions of the Batéké Plateau (City-Province of Kinshasa, DRC). In order to develop a system of direct seeding in a permanent vegetative cover of Stylosanthes guianensis (Aublet) Swartz adapted to the growing conditions of the Batéké plateau, the behavior of improved cassava varieties ZIZILA, TME 419 and BUTAMU was evaluated in sole cropping and in intercropping with Stylo. The trial was conducted from October 2009 to August 2011 in two sites representative of the soil diversity on the plateau. The results demonstrate the existence of a strong competition between the associated crops during the 1st year of cultivation. Yield losses recorded compared to situations of sole cropping ranged on average between 22,6-35% for the biomass of Stylo cut at 8 months in the two trial sites, and amounted to about 50% for cassava harvested at 12 months. Delaying the harvest of cassava to 16 months, with a cutting of the Stylo canopy to form a mulch at the end of the long dry season (8 months after planting), has permitted cassava to reach yields equivalent to the situation of sole cropping. The average yields of fresh cassava roots were significantly lower in the site of Neema (9.7 t.ha-1 at 12 months in sole cropping) compared to those recorded in the site of The Way (12.8 t.ha-1 at 12 months in sole cropping). In each site, no significant difference could be detected for the yields of the compared cassava clones cultivated in pure stand. When harvesting cassava at 12 months, the production of Stylo dry biomass was equivalent at 20 months regardless of the installation mode (sole cropping or intercropping with cassava). The trial did not permit to clearly separate the cassava varieties for their intercropping ability with Stylo. The intercropping of Stylo with cassava is a cost effective method to install a permanent cover in which it is possible to make direct seeding of other crops