Different crop models including MAIZE Ceres, STICS and other approaches have been used to simulate leaf area index (LAI) in maize (Zea mays L.). These modeling tools require genotype-specific calibration procedures. Studies on modeling LAI dynamics under optimal growth conditions with yields close to the yield potential have remained scarce. In the present study, logistic and exponential approaches have been developed and evaluated for the simulation of LAI in maize in a savannah region of the DR-Congo. Data for the development and the evaluation of the model were collected manually by non-destructive method from small farmers' field. The rate of expansion of the leaf surface and the rate of change of leaf senescence were also simulated. There were measurable variations among sites and varieties for the simulated height of maize plants. At all sites, the varieties with short plants were associated with expected superior performance based on simulation data. In general, the model underestimates the LAI based on observed values. LAI values for the genetically improved maize varieties (Salongo 2, MUS and AK) were greater than those of the unimproved local variety (Local). There were significant differences for K, b, T i , LAI, T f , and parameters among models and varieties. In all sites and for all varieties, the growth rate (b) was higher, while the rate of senescence (a) was lower compared to STICS estimates.

Les perspectives de développement de l’élevage caprin semblent favorables en République démocratique du Congo. La connaissance des caractéristiques de l’élevage de la chèvre locale par les éleveurs est un facteur très important pour maîtriser sa production et la favoriser. L’objectif de cette étude a été d’améliorer la productivité de la chèvre locale de Mbanza-Ngungu en accroissant la connaissance de ses performances reproductives. Pour atteindre cet objectif, les données ont été collectées par observation directe des chèvres. Ces données ont permis de calculer par simulation les paramètres de reproduction et de dynamique de la population sur une période de cinq ans. L’étude a montré la pertinence du modèle pour simuler les caractères de reproduction de la chèvre de Mbanza-Ngungu et qu’il est inutile de garder les chèvres plus de cinq ans.

To determine the growing and yield performance of low nitrogen tolerant maize varieties under fertilized and unfertilized conditions, a study was conducted at the Mvuazi Research Center. Nine varieties were tested with and without fertilizer using the micro-dosing method, following the randomized complete block design with two factors. The results showed a difference among varieties in both crop conditions. The average yield with fertilizer was higher than the yield without fertilizer. The varieties LNTP-W C4 and LNTP-Y C7 registered 5.9 t/ha and 3.6 t/ha respectively under fertilized crop conditions and 7.14t/ha and 7.12t/ha under unfertilized crop conditions. Thus, using Low-N can minimize production costs by improving the productivity of soils low in Nitrogen typical of conditions of the southwestern savanna. KEY WORDS: LOW NITROGEN SOIL, LNTP, MAIZE PRODUCTION, FERTILIZER, SAVANNA, INERA-DRC

To determine the growing and yield performance of low nitrogen tolerant maize varieties under fertilized and unfertilized conditions, a study was conducted at the Mvuazi Research Center. Nine varieties were tested with and without fertilizer using the micro-dosing method, following the randomized complete block design with two factors. The results showed a difference among varieties in both crop conditions. The average yield with fertilizer was higher than the yield without fertilizer. The varieties LNTP-W C4 and LNTP-Y C7 registered 5.9 t/ha and 3.6 t/ha respectively under fertilized crop conditions and 7.14t/ha and 7.12t/ha under unfertilized crop conditions. Thus, using Low-N can minimize production costs by improving the productivity of soils low in Nitrogen typical of conditions of the southwestern savanna.

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