Abstract—Phosphorus (P) is rapidly bound in many natural and agricultural ecosystems due to elusive biogeochemical characteristics of soils rendering this non-renewable natural resource the most immobile and inaccessible nutrient to many crop plants. Plans display a myriad of rescue responses to combat this P-starvation such as enhanced P-acquisition and P-use efficiency, differential adaptive growth responses and preferential allocation of resources under P-stress environment. To elucidate P-starvation induced differential growth response and P-acquisition from sparingly soluble tri-calcium phosphate ((Ca3(PO4)2); four genetically diverse wheat cultivars were grown in a solution culture in a climatically controlled growth chamber. Seven-day-old uniform sized pre-germinated uniform seedlings of cultivars were transplanted in 3-L capacity pots containing NH4H2PO4 (AP) @ 200 µM P L-1 as an adequate (control) level and (Ca3(PO4)2 (TCP) @ 0.2 g L-1 in a bid to maintain deficiently buffered P-stress environment during entire growth period. Orthophosphate concentration ([P]) and uptake in plant parts, and P-absorption, transport and utilization rates were substantially different in wheat cultivars indicating considerable genetic variability in tested cultivars. Highly significant correlations were observed between P-concentration and contents and growth related parameters. Relative growth rate of root was correlated significantly with root and total dry biomass of plants. Mean P-transport rate increased about 1.95-fold with adequate P-supply compared to sparingly soluble P in the rooting medium. Under P-starvation, more biomass accumulation by class-I (low P-tolerant/P-efficient) cultivars than class-II (low P-sensitive/P-inefficient) cultivars might be due to their better acquisition and utilization of P from sparingly soluble P from the rooting medium.

Index Terms—P-acquisition, P-starvation, tri-calcium phosphate ((Ca3(PO4)2), wheat cultivars.

The authors are with Department of Environmental Management Engineering, Graduate School of Environmental & Life Science, Okayama University, Okayama, Japan.
M. Shahbaz Akhtar is also with Department of Soil & Environmental Sciences, University College of Agriculture, University of Sargodha, Sargodha, Pakistan.

Cite: M. Shahbaz Akhtar, Yoko Oki, Yoshitaka Nakashima, "Differential P-Acquisition and Growth Characteristics of Wheat Cultivars under Buffered P-Stress Environment vol. 5, no. 5, pp. 311-320, 2015.