Phosphorus use efficiency of improved faba bean (Vicia faba) varieties in low-input agro-ecosystems

The use of phosphorus (P)-efficient legumes is a prerequisite for sustainable intensification of low-input agro-ecosystems. A study was undertaken in a farmer's field in the tropical highlands of Ethiopia to assess the agronomic performance, P acquisition efficiency (PAE), and P utilization efficiency (PUE) of six improved faba bean varieties (Vicia faba L. var. CS-20DK, Degaga, Gebelcho, Moti, Obse, Walki) without and with P application. Varieties showed significant variations in PUE, but P application had no significant effect on PUE. Variety Moti demonstrated highest PUE of 272 kg grain kg(-1) P, which was 1.6-fold higher than the lowest PUE (164 kg grain kg-1 P) of Gebelcho. PUE was significantly and positively correlated with grain yield (r = 0.542) and negatively correlated with shoot PAE (r = -0.541), indicating that PUE is important for grain yield. The results demonstrate that variations in grain and biomass yield of faba beans were largely due to differences in PUE and not due to PAE. Therefore, we argue that genetic resources of faba bean varieties showing optimal agronomic performance and high PUE in low-input agro-ecosystems should be better explored. Introduction of such varieties in low-input cereal-based cropping systems could improve and enhance P use efficiency at the system level.

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