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PHOSPHORUS UTILIZATION BY SIX BRASSICA CULTIVARS (BRASSICA JUNCEA L.) FROM TRI-CALCIUM PHOSPHATE; A RELATIVELY INSOLUBLE P COMPOUND

TARIQ AZIZ¹, RAHMATULLAH², MUHAMMAD AAMER MAQSOOD², MUKKRAM. A. TAHIR², IFTIKHAR AHMAD³ AND MUMTAZ A. CHEEMA⁴

Abstract: Phosphorus deficiency is a serious concern for agriculture productivity around the globe. It readily forms insoluble compounds by reacting with calcium after addition to calcareous soils. We evaluated six Brassica cultivars for P utilization from mono-ammonium phosphate (a soluble source) and a relatively insoluble P compound (Tri-calcium phosphate). Plants were germinated in sand and transplanted in a P-free Johnson’s nutrient solution contained in two iron tubs. Phosphorus (@ 0.2 mM P) was applied in each tub using both sources. Cultivars differed significantly for their biomass grown with either source of P. Biomass was significantly (p<0.05) lower in plants grown with TCP than those grown with MAP. Relative shoot dry matter of plants grown with TCP compared to those grown with MAP varied from 45% in BARD-1 to 96% in 19-H. However 19-H exhibited lowest dry matter with both P sources indicating its inefficiency. Root:shoot ratio differed significantly among cultivars, however it was not much affected by P source. Cultivars RL-18, Raya Anmol, and KS-74 produced maximum shoot dry matter grown with TCP, however in plants grown with MAP, Poorbi Raya produced maximum dry matter indicating its high responsiveness but lower P solublization. Phosphorus uptake in both shoots and roots of plants grown with MAP was significantly more than those in TCP. Total P uptake in plants grown with TCP varied between 8.56 mg/plant in 19-H to 22.86 mg/plant in Poorbi Raya. However, relative P uptake was highest in 19-H indicating that its poor performance in MAP treatment was not because of lower P availability in growth medium but it was due to its lower P utilization efficiency. Phosphorus utilization efficiency was maximum in Poorbi Raya, RL-18 and BARD-1 when grown with MAP, while in plants grown with TCP, Raya Anmol and RL-18 exhibited maximum P use efficiency. However, P efficiency mechanisms of these cultivars must be studied in further physiological and morphological studies.

¹ Sub-Campus University of Agriculture, Faisalabad at Depalpur, Okara.
²Institute of Soil & Environmental Sciences, University of Agriculture, Faisalabad.
³ LRRI, Pakistan Agricultural Research Council, Islamabad.
⁴ Department of Agronomy, University of Agriculture, Faisalabad.

Corresponding Author: Dr. Tariq Aziz; tasuaf@hotmail.com