DIFFERENTIAL GROWTH RESPONSE, PHOSPHORUS ABSORPTION, TRANSPORT AND UTILIZATION BY WHEAT GENOTYPES UNDER PHOSPHORUS DEFICIENCY

Abstract

Genotypic differences in phosphorus (P) acquisition and/or utilization can be exploited to enhance the efficiency of P fertilizers and crop productivity on P-deficient soils. Wheat genotypes were evaluated for relative growth rate, P absorption, transport and utilization in a hydroponic study at deficient P (10 µM) and adequate P (200 µM) levels. Phosphorus deficiency drastically reduced dry matter production, P accumulation in root and shoot, relative growth rate (RGR) of shoot, P absorption rate (PAR), and P transport rate of wheat genotypes. However, root- shoot ratio, RGR of root, and P utilization rate (PUR) of shoot and root increased significantly (P ? 0.001) in response to P deficiency. The genotypes SDW-4, SWD-6, YCBW-10 were found superior regarding dry biomass production and relative growth rate of shoot at low P, and therefore can be considered as P-efficient. Strong positive correlation of shoot dry matter with PUR of shoot (r = 0.80, P ? 0.001), while a non-significant relationship with PAR (r = 0.12, P ? 0.05) showed that P utilization was the dominant mechanism for high P efficiency in most of genotypes under P deficiency. The P-efficiency of SDW-6 and YCBW-10 at low P level could be explained by their higher PAR and PUR. However, P utilization appeared to be the main strategy for high P efficiency in SDW-4. The results suggested that wide variations exist among wheat genotypes for mechanisms responsible for P efficiency under low P supply which can be exploited in breeding ventures.

Keywords

• absorption rate
• relative growth rate
• transport rate
• utilization rate
• wheat genotypes