Temporal tillering behavior of Sri Lankan elite rice varieties in response to phosphorus availability

Tillering is closely related to environmental conditions including the accessibility to nutrients. Phosphorus (P) availability affects tillering dynamics in rice. A hydroponic experiment was conducted to identify the tillering dynamics of forty eight elite rice varieties in response to optimum (50 μM) and deprived (10 μM) P status in the growing medium. Results showed that there was a significant delay in tillering in P deprived condition. Days taken to tillering, shoot dry weight, root dry weight, growth rate, shoot P concentration, P uptake rate, P utilization efficiency and shoot : root dry weight ratio at the time of tillering were affected by the variety and level of P supply. There was no relationship between the time to initiate tillering and the age for maturity of a rice variety. The variety Bg 94-1showed least delay in tillering followed by Bg 454 and At 353 and they were identified as tolerant varieties while most of elite rice varieties were identified as susceptible rice varieties for P deficiency tolerance. Furthermore, days taken for tillering can be used as a nondestructive criterion in selecting plants in segregating populations at early growth stages for P deficiency tolerance.