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Landrace of japonica rice, Akamai exhibits enhanced root growth and efficient leaf phosphorus remobilization in response to limited phosphorus availability

Dissanayaka, D. M. S. B., Maruyama, Hayato, Nishida, Sho, Tawaraya, Keitaro, Wasaki, Jun
Plant and soil 2017 v.414 no.1-2 pp. 327-338
cultivars, inflorescences, inorganic phosphorus, plant organs, rice, landraces, developmental stages, shoots, acclimation, soil, grain yield, root growth, roots, leaves, crops
AIMS: Phosphorus (P) acquisition through extensive root growth and P allocation to different plant organs through efficient remobilization are important for acclimation of crop plants to P-limited environments. This study elucidated changes in rice root growth and leaf P-remobilization and their influence on grain yield under P deficiency. METHODS: Two pot experiments were conducted with (P100) and without (P0) inorganic P supply using two Japanese rice cultivars: Akamai (Yamagata) and Koshihikari. Multiple harvests were made until the panicle initiation stage. Root and shoot growth response, P acquisition, and temporal leaf P-remobilization efficiency were measured. A separate experiment ascertained the final yield and grain P status. RESULTS: The Akamai rice cultivar showed enhanced root growth and more acquired soil P. The Akamai root dry weight was 66% greater than that of Koshihikari under P0. Confronting P deficiency, Akamai remobilized some P from its lower mature leaves to upper younger leaves starting from early growth. The remobilized P fraction increased to 72% at panicle initiation under P0. Under P0, Akamai exhibited two-fold higher leaf P-remobilization efficiency than under P100. CONCLUSIONS: Enhanced root growth that facilitates acquisition of more soil P through better soil exploration coupled with efficient leaf P remobilization from the early growth stage improves adaptation of Akamai rice cultivar to P-limited environments. Nevertheless, P-starvation responses did not facilitate higher grain yields in P-limited conditions.