Allelochemicals as Growth Stimulators for Drought Stressed Maize

Abstract

Sorgaab, an aqueous extract of sorghum leaves was applied to probe the mod-ulation in growth and physiological attributes of maize under drought in lab and greenhouse studies. Sorgaab soaked seeds (10 dilutions) were germinated to assess drought tolerance at germination and seedling growth stages. More concentrated Sorgaab solutions (2 mL • L −1) were damaging, while lower con-centration in the range of 0.75 to 1.5 mL • L −1 improved the root and shoot growth of maize under drought. Applied drought stress decreased chlorophyll b greater than chlorophyll a that improved the chl a/b ratio. Application of Sorgaab also improved the internal CO 2 assimilation, which increased the net photosynthesis and A/E ratio of drought affected plants. Soluble phenolics and anthocyanins were also more increased in plant receiving Sorgaab under drought than control. Although greater concentrations of phenolic acids inhi-bit the uptake of ions, but its lower concentrations stimulate the uptake of K + , Ca 2+ , NO 3 , PO 4 . In conclusion, although high concentrations of Sorgaab re-duced the growth of plants, it might alleviate the adverse effects of drought, if applied at the low concentration. Dilute concentrations of Sorgaab can be uti-lized as a natural source for improving drought resistance in maize both at germination and later growth stages.