Southern Africa Drought and Low Fertility (SADLF) project breeders have developed 'nitrogen use efficient' (NUE) maize genotypes, selected under both managed nitrogen stress and optimum nitrogen conditions. An experiment was conducted during the 2000-2001 season to test the response of these genotypes to several rates of mineral N applied on farmers' fields. The aim was to determine whether the new genotypes offer better returns to the small amounts of expensive N fertilizer that farmers now apply. Four NUE genotypes (two hybrids and two open pollinated varieties (OPVs)) and a commercially available check hybrid (SC501 ) were evaluated at 0, 15, 30, 60 and 90 kg ha-1 of applied N. The experiment was conducted in four districts in sub-humid and semi-arid zones of Zimbabwe. Maize grain yield response to N was larger at the more fertile sites with short cropping histories, but there was no response at some depleted communal area sites. There was preliminary evidence that the elite NUE maize hybrids can provide more grain with modest amounts of N fertilizer than can the commercially available hybrid SC501. CML395/CML312//CML440 had the highest grain yield and CML395/CML312//CML440 and CML395/CML444//CML440 had the highest biomass at the responsive sites. At the less responsive degraded sites, there was no difference between varieties for any measured trait. There were some indications that experimental genotypes had higher NUEs. On average, varieties selected for NUE produced 17 kg grain per kg of N applied, whilst the check entry produced ]0 kg grain per kg N applied. More data are required from infertile communal area fields that are so widespread in Zimbabwe.

Research and Partnership Program

English

0409|AGRIS 0401|AL-Maize Program

Juan Carlos Mendieta

INT1888

CIMMYT Staff Publications Collection