Response of Bread Wheat (Triticum aestivum L.) Varieties to Split Nitrogen Applications in Dedessa District, Southwest Ethiopia

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.