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

Crop rotation effects on grain yield and yield components ofbread wheat - Tilahun et al.
found that faba bean, field pea and linseed in that order are the best beneficial break crops in
wheat production. Therefore, a crop rotation experiment was conducted on bread wheat to
evaluate the effect of different break crops on the grain yield and yield components of bread
wheat; and to determine the most beneficial precursor crop in wheat production.
MATERIALS AND METHODS
Treatments and Experimental Design
A crop rotation study was executed for bread wheat at Sinana on-station during bona (meher)
(August to December) season of 1995-98 and gena (belg) (April to August) of 1996 and 1997
seasons on two separate fields for each season. Precursors were grown during gena 1996 and
bona 1995 and 1997 seasons while the principal crop was grown in alternate years i.e. gena
1997 and bona 1996 and 1998 seasons.
The treatments were laid out in a randomized complete block design with three replications.
Six precursor crops, bread wheat, barley, emmer wheat, faba bean, field pea and linseed, and
two rates of fertilizer, 9-23 and 41-46 N-P 2 0 S kglha, were sown each on a plot size 20 m 2
having 20 rows of 5 m length. The distance between the rows was 20 cm. Urea and DAP
were used as sources of fertilizer. Similar fertilizer rate was applied on both precursor and
principal crop to minimize the variation of soil fertility. The arrangement and rates were
repeated up to the end of the project. The experimental land was plougbed by tractors and
row planting was made manually. Sowing dates ranged between mid August to early
September. The variety ET -13 was used as a principal crop. The treatments were shown in
Table 1.
Data Collection and Measuring Methods
At maturity, plant height, productive spikes m- 2 , and spike length were measured. Fourteen
central rows of 5 m length (14 m 2 ) was harvested manually to measure grain and biomass
yield. Thousand-kernel weight was measured from the sample grain yield. Harvest index was
calculated from grain and biomass yields. The other parameters were calculated in the
2
following steps: (1) grain yield (g) spike-I = (grain yield (kg ha- I )1l0)/(spikes m- ); (2) kernel
spike-I = (1000 kernels/weight of 1000 kernels (g)*yield spike- l (g); (3) kernels m- 2 = (kernels
spike-')*(spikes m- 2 ); and (4) straw yield (kglha) = biomass yield (kglha) - grain yield
(kglha).
Statistical Analysis of Agronomic Parameters
Data were subjected to analysis of variance using MST ATC microcomputer software.
Parameters of the principal crop were analyzed each year separately. Treatment degrees of
freedom (df) and total sum of squares of precursor were partitioned by orthogonal contrasts
into 5 meaningful single df components for each parameter. The major groups are:
1. Pulses vs. cereals and linseed
2. Cereals vs. linseed
3. Within cereal group, wheat vs. barley
4. Within wheat, bread wheat vs. emmer wheat
5. Within pulses, faba bean vs. field pea
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