Genetic Variations of Brassica Cultivars for P Acquisition in a P Stress Environment and Comparison of P Sources for Sustainable Crop Management
2009
Akhtar, M Shahbaz | Oki, Yoko | Adachi, Tadashi
To compare the growth performance of Brassica in a phosphorus (P) stress environment and response to added P, six Brassica cultivars were grown in pots for 49 days after sowing, using a soil low in P [sodium bicarbonate (NaHCO3)-extractable P = 3.97 mg kg-1, Mehlich III-extractable P = 6.13 mg kg-1] with (+P = 60 mg P kg-1 soil) or without P addition (0P). Phosphorus-stress markedly reduced biomass accumulation and P uptake by roots and shoots. However, root-shoot ratio remained unaffected, implying that relative partitioning of biomass into roots and shoots had little role to play in shoot dry matter (SDM) production by cultivars. Biomass correlated significantly (P < 0.01) with total P uptake. Under P stress, the cultivars that produced greater root biomass were able to accumulate more total P content (r = 0.95**), which in turn was related positively to SDM and total biomass (r > 0.89**) and negatively to P-stress factor (r = -0.91**). There was no correlation between P efficiency (PE) (relative shoot growth) and plant P, but PE showed a very significant correlation with shoot P content and SDM. Wide differences in growth and better performance of cultivars such as 'Brown Raya' and 'Con-1' under P stress encouraged screening of more germplasm, especially in the field, to identify P-tolerant cultivars.
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