Modification of physiological responses of water stressed Zea mays seedlings by leachate of NicotiaNa plumbagiNifolia

The present study deals with the effects of allelochemicals present in leachate on the drought response of maize plants. Nicotiana plumbaginifolia was selected as a donor plant. 12-d-old maize (Zea mays L. cv. Uttam) seedlings with and without leachate were subjected to water stress (WS) by withholding water supply for 6 days. Leaf water status, photosynthetic pigments, protein content, proline, nitrate reductase activity (NRA) and activities of antioxidant enzymes were examined in 18-d-old seedlings. Root and shoot lengths of seedlings decreased in all treatments except in the water stressed seedlings where an increase in root length was recorded. WS decreased relative water content (RWC), pigments and protein content. The decrease was significant when the plants were subjected to both WS as well as allelochemical stress (AS). The higher concentration of leachate caused a drastic decrease in NRA under WS. Superoxide dismutase (SOD) and catalase (CAT) activities were significantly increased under WS. POX activity was not significantly increased under WS alone, but it was significant for the combined stress. However, the higher concentration of leachate (N75 and N100) caused a decrease of these antioxidants. Accumulation of proline was stimulated in plants under WS and WS+AS. Root proline was higher than shoot proline. Impairment of metabolic activities due to WS and the combined effect of WS+AS resulted in inhibited plant growth. The effect of WS was more pronounced in seedlings already experiencing allelopathic condition.