PHOSPHORUS AND ZINC NUTRITION IN MAIZE (ZEA MAYS L.) UNDER DROUGHT STRESS

Drought stress causes negative effects on soil nutrients dynamics as well as their mutual interactions. Negative interaction between phosphorus (P) and zinc (Zn) vis-a-vis plant uptake exists under adequate moisture availability but this phenomenon is still unclear under drought condition. A pot study was conducted to investigate the effect of this interaction on maize plants (var. FH-1046) at three moisture levels, viz., optimum (80% of water holding capacity-WHC), moderate drought (50% of WHC) and severe drought (30% of WHC). The P and Zn were added alone (only-P and only-Zn) or in combination (P + Zn) at the rate of 57 and 6 mg kg(-1) soil at three moisture levels with complete randomization. Soil moisture levels were introduced after two weeks of plant growth and maintained after every three days by weighing. After 60 days of plant growth, plants were harvested and analyzed for their growth and nutrients contents, viz., P, Zn, nitrogen (N), and potassium (K). The findings showed that combined P and Zn caused a significant reduction in P and Zn contents at the root and shoot levels at higher moisture ( 80% and 50% of WHC) relative to alone P and Zn additions, but the extent of this reduction reduced with increasing drought intensity, showing the negative effect of drought on plant nutrients uptake. The effect of combined nutrients addition was positive on plant growth and the absence of P (only Zn addition) reduced plant height by 14% and 28% at 80% and 30% of WHC levels. Shoot and root dry weights increased significantly by 41% and 43% with combined P and Zn applications. The plant growth also declined with the increasing drought levels. Under severe drought (30% of WHC), the extent of the negative interaction of P and Zn diminished considerably but there was an overall negative effect on plant growth and nutrient contents at 30% of WHC. The findings suggest that increasing drought intensity can reduce the negative effect of P and Zn on each other's uptake and accumulation in plants but with concurrent reductions in absolute nutrients contents and plant growth.