Abstract:
Foliar urea application is one of the nitrogen (N) application methods in cereal grain
crops. Yield and yield components may be affected by foliar urea application. To investigate
the effect of rate and time of such treatment on yield and yield components of two
winter wheat cultivars, a field experiment was conducted at Badjgah, Agricultural Research
Farm (29° 36 N, 52° 32 E) of Shiraz University, Shiraz, Iran during 1998-99 growing
season. The experimental treatments were two winter wheat cultivars (‘Phalat’ and
‘Marvdasht’), five levels of foliar urea application (0, 8, 16, 24 and 32 kg N ha-1) at three
times of application (pre-anthesis, anthesis and post-anthesis). The experimental design
was a randomized complete block one with treatments arranged as split-plot factorial
with three replicates. The results showed that cultivars responded differently to the rate
of foliar N feeding so that, over the growth stages, Marvdasht cultivar produced significantly
greater grain yield (+19%) by application of 8 kg N ha-1, whereas, the Phalat cultivar
had greater grain yield (+27%) when it was supplied by 16 kg N ha-1. Increase in
grain yield was mainly due to an increase in number of grains ear-1. The fertile ears m-2
and mean grain weight were not significantly affected by foliar urea feeding, however, the
harvest index and biological yield were increased. The pre-anthesis foliar feeding with
urea resulted in higher yields as compared with later applications. Also the early foliar
urea feeding increased the harvest index from 42.4% to 46.9% at 32 kg N ha-1 in
Marvdasht cultivar. The results of the present investigation also suggest that late foliar
application could decrease nitrogen use efficiency.
