The Eleventh Regional Wheat Workshop For Eastern ... - Cimmyt

Response ofsome durum wheat landraces to nitrogen application - Teklu et al.
determine the optimum levels for economically profitable yields (DZARC, 1988; 1989).
Results indicate that N rates had significant effect on yield up to 230 kg ha- l (Samuel, 1981;
Desta, 1988; Miressa, 1992; Lemma et al., 1992). On the whole, the new high yielding
cultivars have a higher nutrient requirement because of their increased yield potential.
In spite of this, there is as yet little information on the differential fertilizer responses of high
yielding durum wheat lines selected from the Ethiopian landrace population to increasing
rates of N on Vertisols in the central highlands. Therefore, this study was launched to partly
supply this information.
MATERIALS AND METHODS
A factorial experiment in a randomized complete block design with three replications was
conducted at Akaki and Cheffe Donsa on pellic Vertisols for three main cropping seasons
(1993/94-1995/96). The experiment was conducted on flat seedbed of 4 by 4 m using three
promising landrace durum wheat genotypes selected from their respective location.
Consequently, A2-138, EI-9 and BI-9 were selected from Akaki, with Kilinto and DZ04-118
as the local and standard checks, respectively. At Cheffe Donsa, A2-187, AI-138 and BI-9
were the landraces while DZ-320 and DZ04-118, in that order, were the local and standard
checks. These were broadcast at seeding rates recommended for each landrace variety.
Nitrogen levels were 0, 23, 46, 69, 92 and 115 kg N ha- l as urea applied in split; half at
sowing and the other half at full tillering. Fifteen kg P ha- I was uniformly broadcast and
incorporated into the soil at sowing. Grain and straw yield responses were recorded.
RESULTS AND DISCUSSION
Akaki: There were significant differences in both grain and straw yields throughout the three
years due to varieties as well as nitrogen application rates (Tables 1 and 2). The interaction
effect between the varieties and N rates, however, was significant in two and one out of the
three years for grain and SY, respectively. The results conform to the findings of Miressa et
al. (1992) who reported varietal effect on nitrogen uptake in durum wheat. During the first
year (1993/94), EI-9 gave the highest GY 3504 kg/ha followed by BI-9 and A2-138,
respectively, while the standard check DZ04-118 gave the least GY (2993 kglha). For
reasons not clear, the highest GY (3662 kg/ha) due to 92 kg N/ha was not significantly
different from 3318 kglha obtained with the application of 23 kg N/ha. Similarly, the GY
obtained with no N fertilizer application was not significantly different from the amount
obtained due to 46 kg N/ha. Further application of N above 92 kg N/ha resulted in slightly
reduced GY. Similar to the GY, EI-9 gave the highest SY followed by BI-9 and A2-138. The
highest mean SY (5350 kg/ha) was obtained with the application of the highest N (115 kg/ha)
followed by 5338 and 5102 kg/ha obtained with 69 and 92 kg N/ha, respectively, against the
least which was obtained from the no N fertilizer treatment. As opposed to the GY, the
highest N rate did not result in reduced SY. Generally, there was a consistent increase in SY
with increase in N application rates as expected due to the positive role of N on vegetative
growth.
In 1994/95, unlike the previous year, the interaction effect of the varieties and the nitrogen
application rates was significant for both grain and SY. DZ04-118 gave the highest grain and
SY while A2-138 gave the least. The highest GY of 2386 kg/ha and SY of 3207 kglha were
obtained with N application rate of 92 kg N/ha, but the GY was not statistically greater than
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