A field experiment was conducted at the National Maize Research Program (NMRP), Chitwan, Nepal during summer of 2014 to evaluate the response of tillage methods (conventional and zero tillage) and nitrogen levels (0, 60, 120 and 180 kg ha-1) on grain yield of two maize (Zea mays L.) hybrids (Rampur hybrid-2 and RML32/RML17). The experiment was laid out in strip-split plot design consisting of sixteen treatments with three replications. Growth and yield parameters of maize were measured and economic analysis was conducted during plant growth and after harvest. The maize hybrids, Rampur hybrid-2 and RML32/RML17, and tillage methods, zero tillage and conventional tillage, had similar grain yield (2.9 t ha-1). The grain yield obtained from control without nitrogen application (1.64 t ha-1) was significantly lower than that of all levels (60, 120 and 180 kg ha-1) of nitrogen. The grain yield (3.57 t ha-1) obtained with 180 kg N ha-1 was significantly higher than 60 kg N ha-1 (3.05 t ha-1) but was at par with 120 kg N ha-1 (3.44 t ha-1). The difference between 120 and 60 kg N ha-1 application with respect to grain yield was non-significant. Grain yield increased non-linearly with increasing levels of N application, while the physical and economical maximum doses of nitrogen equaled to 172.38 and 153.77 for zero tillage, and 140.00 and 127.86 kg ha-1 for conventional tillage methods, respectively. Results highlight the potential use of zero tillage with 120 kg ha-1 nitrogen level in hybrid varieties to harness agronomic and economic benefits in the inner Terai region of Nepal during summer season.
Key words: Maize hybrids, tillage, nitrogen, yield.
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