Abstract:
Bread wheat is an important staple and cash crop grown by smallholder farmers in the
highlands of Ethiopia. However, the productivity of the crop is constrained by low soil
fertility and poor nitrogen (N) fertilizer management. Application of N fertilizer at the right
rate and split timings is essential for the improvement of soil fertility, crop productivity and
enhanced total N uptake by crops. Therefore,this experiment was conducted to assess the
response of bread wheat varieties to split N application on grain yield, N concentration and
uptake.A field experiment was conductedin Dedessa district, southwest Ethiopia in 2018.
Factorial combinations of three bread wheat varieties (Hidase, Ogolcho and Danda’a) and
three split N applications (¼ at sowing + 1/2at mid-tillering + 1/4at anthesis, 1/3 at sowing +
1/3mid-tillering + 1/3 at anthesis and ½ at sowing + ½ mid-tillering,0 at anthesis) were
combined. The experiment was laid out in a split plot design with three replications. Varieties
were assigned on the main plots and splits N application to the subplots.Variety Ogolcho had
higher value for number of effective tiller m2(65),length of spike(9.75),number of kernel
(53),harvest index(53.7%), thousand seed weight(43.55g),grain yield(3965 kgha-1),partial
factor productivity (2641 kg grains kg-1 N)and grain N uptake(67.1kgha1). On the other hand,
Danda’a variety exhibited greater values for straw yield(5060 kgha1), total biomass
yield(7715 kgha-1).SplitNapplication had significant effect on the yield and yield component
ofbread wheat. Split Napplication 1/4 at sowing + 1/2at mid-tillering + 1/4 at anthesis gave the
highestlength of spike (10.83cm),number of effective tiller m2(65.5), number of kernel per
plant (52.77),thousand seed weight (45.2g) and harvest index(57%), partial factor
productivity (26.8 kg grains kg-1 N),compared to the rest ofsplit Napplication. Split N
application ¼ at sowing + 1/2 at mid-tillering + 1/4at anthesis gave the highest grain yield,
partial factor productivity and total N uptake than the rest application methods. This
application method gave a yield advantage of 18.24 % over commonly practiced 1/2 at sowing
and 1/2 at mid-tillering and 0 at anthesis,respectively. It also gave the highest grain N
uptake(69.2 kgha-1) and total N uptake(109.4 kgha-1). This study indicates that variety
Ogolcho had the highest grain yield, partial factor productivity and total N uptake than the
rest varieties with split N fertilizer applications of (1/4 at sowing + 1/2 at mid-tillering 1/4 at
anthesis.It is better to do further research on split N application with different sole N rate
across different soil types, years and locations to draw sound recommendation.
