Agronomic response of drought-tolerant and Striga-resistant maize cultivars to nitrogen fertilization in the Nigerian Guinea savannahs

摘要

In additon to drought and Striga hermonthica parasitism, nitrogen deficiency is a major constraint to maize production in the Guinea savannahs of Nigeria. The use of mineral fertilizers is limited because of unavailability and high costs. The use of maize cultivars that perform well under sub-optimal N conditons is therefore desirable. Breeders at IITA have selected maize cultivars that combine tolerance to drought and Striga hermonthica parasitism. This study evaluated six of these cultivars under arange of N application rates and compared these with a widely grown variety, TZB-SR. The study was conducted in Zaria and Samaru Kataf in Kaduna State of Nigeria. Results showed N application significantly reduced days to flowering and increased yield and yield components. Cultivars selected for combined tolerance to drought and Striga recorded lower number of days to flowering under N stress and higher dry matter, higher grain yield, higher number of grains m~(-2) and higher 500-seed weight at all N rates. This confirms earlier reports that maize cultivars selected for tolerance to drought will perform well under N-limited conditions. Grain yield was significantly associated with dry matter, number of grains m~(-2) and 500-seed weight at all N levelssuggesting that these agronomic traits are significant determinants of maize yield at all N rates. Two cultivars (DT SIR SYN-W/IWD C3 SYN and IWD C3 SYN/DT-SYN-1 -W) were particularly outstanding at all added N levels probably due to long term improvement for drought tolerance. These two cultivars can be recommended for large-scale demonstration and release to the farmers in the West African savannas.