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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Maize production in tropical Africa is often negatively affected by drought. The main objectives of the present study were to 1) analyze the impact of water stress on the agro-morphological performance of two varieties of Quality Protein Maize (QPM) compared to two normal maize varieties and 2) assess their adaptive response in contrasting water environments. Agro-morphological responses to water deficiency of maize (Zea mays L.) were assessed in controlled experiments using four maize varieties, two normal maize (Zm725 and Mus1) and two quality protein maize (Mudishi1 and Mudishi3) varieties. They were subjected to three water regimes (100%, 60%, 30% water retention capacity) at the beginning of the bloom stage, using a Fischer block design with four replications. Significant differences (p < 0.05) among varieties, water regimes and their interactions for plant growth and production parameters were observed. Reduction of water supply to plants caused changes in aerial and underground plant growth. Plant stem height, foliar expansion, and root system development characterizing vegetative growth showed variation in varietal response to water regimes. Mus1 (normal maize variety) was the best adapted to variations in water regimes because they developed an important root volume to adapt to the effects of water deficit while maintaining their morphological and productive characteristics.

Logistic and exponential approaches have been used to simulate plant growth and leaf area index (LAI) in different growing conditions. The objective of the present study was to develop and evaluate an approach to simulate maize LAI that expresses key physiological and phonological processes using a minimum entry requirement for Quality Protein maize (QPM) varieties grown in the southwestern region of the DR-Congo. Data for the development and testing of the model were collected manually in experimental plots using a non-destructive method. Simulation results revealed measurable variations between crop seasons (long season A and short season B) and between the two varieties (Mudishi-1 and Mudishi-3) for height, number of visible leaves, and LAI. For both seasons, Mudishi-3, a short stature variety was associated with expected stable yield based on simulation data. In general, the model simulated reliably all the parameters including the LAI. The LAI value for mudishi-1 was higher than that of Mudishi-3. There were significant differences among the model parameters (K, Ti, a, b, Tf) and between the two varieties. In all crop conditions studied and for the two varieties, the senescence rate (a) was higher, while the growth rate (b) was lower compared to the estimates based on the STICS model.