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Abstract
Phosphorus (P) plays a central role in plant cell metabolism. Therefore, low P availability is one of the major constraints for plant productivity in natural and agricultural ecosystems. The addition of phospahtic fertilizers is economically not feasible for resource-poor farmers as the efficiency of added P fertilizers is often low. Plants have evolved a myriad of adaptive mechanisms to increase P uptake and P-utilization efficiency (PUE). Plant efficiency for P uptake and PUE may contribute to improve crop-yield potential in resource-poor environments and selection of P-efficient cultivars can enhance productivity on low fertility soils and reduce fertilizer requirements. A controlled-climate chamber was used to investigate the performance of 14 hydroponically grown Brassica cultivars. Cultivars differed significantly in biomass accumulation (shoot and root dry matter), root-shoot ratio, P concentrations and contents in plant parts, relative reduction in biomass accumulation due to P stress or P-stress factor (PSF) and PUE indicating considerable diversity among the tested cultivars. PUE and the proportional increases in shoot dry matter (SDM) production (SDMmax/SDMmin) in response to the P levels assisted in differentiating plants into efficient and inefficient utilizers of the absorbed P. Cultivars were classified into efficient responsive (ER), efficient non-responsive (ENR), non-efficient responsive (NER) and non-efficient non-responsive (NENR). Efficient cultivars showed the lowest shoot P concentrations and PSF, and the highest biomass accumulation and PUE.
Acknowledgements
The principal author M. Shahbaz Akhtar gratefully acknowledges the Ministry of Education, Science, Sports and Culture (MEXT), Japan, for partial financial support which enabled him to pursue this research work.
