Abstract:
Common bean (Phaseolus vulgaris L.) is an important food and cash crop in southwest
Ethiopia with multiple uses. Productivity of the crop is, however, low at national as well as
regional levels, mainly due to low soil fertility. Phosphorus (P) deficiency is particularly
important in acid soils of southwest Ethiopia affecting growth and yield of seed legumes in
general and that of common beans in particular. Cultivar differences are known to exist in
response to performance under low P and acidity conditions. Therefore, a field experiment
was conducted to assess the response of common bean cultivars to P application on Nitisols
of Jimma in 2016 main cropping season. The treatments consisted of three common bean
cultivars (Ibbado, Tatu, and Remeda) and four P fertilizer rates (0, 23, 46, and 69 kg P2O5 ha1
). The experiment was laid out in a Randomized Complete Block Design in a factorial
arrangement replicated three times. Growth parameters, Phenological parameters and Yield
parameters were collected and statistically analyzed using SAS version 9.2 software. P use
efficiency of the cultivars under the different P application rates was also assessed. Results
indicated that the main effect of P significantly (P < 0.01) influenced number of primary
branches and harvest index. Highest number of primary branches (3.25) and harvest index
(48.63%) were recorded at application of 69 kg P2O5 ha-1
. The main effect of cultivars
significantly (P < 0.01) influenced plant height, hence Remeda was the tallest plant (53.24
cm). The interaction effects of cultivars and P rates also significantly (P < 0.01) influenced
days to 50% flowering, days to 90% physiological maturity, root length, number of nodules,
nodule dry weight, number of pods per plant, number of seeds per pod, pod length, hundred
seed weight, dry biomass yield and seed yield. The highest dry biomass yield (5874 kg ha-1
)
and seed yield (2821 kg ha-1
) were obtained from the treatment combination of cultivar Tatu
and 69 kg P2O5 ha-1
. The P use efficiency parameters (recovery efficiency, agronomic
efficiency) were also significantly affected by the interaction effect of cultivar and P
application rate. Cultivar Tatu was found to be more P efficient at P rate of 23 kg P2O5 ha-1
.
In conclusion, the study pointed out that common bean cultivars responded differently to the
various P application rates suggesting the possibility of exploiting cultivar differences to
combat P deficiency under acidic conditions. Phosphorus at rate of 23 kg ha-1 will be
recommendable for P-efficient cultivar based on phosphorus use efficiency parameters.
Accordingly, Farmer who have no capacity to buy fertilizer cultivar Tatu was recommended
to specific soil of study area. However, since the data is only for one season and location
repeating the experiment across location may be helpful to validate the results.
