JOURNAL OF AGRICULTURE & SOCIAL SCIENCES ISSN Print: 1813–2235; ISSN Online: 1814–960X 10–067/AWB/2011/7–2–56–62 http://www.fspublishers.org Full Length Article To cite this paper: Ali, Z., S.M.A. Basra, H. Munir, A. Mahmood and S. Yousaf, 2011. Mitigation of drought stress in maize by natural and synthetic growth promoters. J. Agric. Soc. Sci., 7: 56–62 Mitigation of Drought Stress in Maize by Natural and Synthetic Growth Promoters ZAFAR ALI, SHAHZAD MAQSOOD AHMED BASRA 1 , HASSAN MUNIR 1 , ARSHAD MAHMOOD† AND SHAHIDA YOUSAF‡ Department of Crop Physiology, University of Agriculture, Faisalabad, Pakistan †Agronomic Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan ‡Social Sciences & Humanities, University of Agriculture, Faisalabad, Pakistan 1 Corresponding author’s e-mail: shehzadbasra@gmail.com; hmbajwa@gmail.com ABSTRACT Drought is an important factor-limiting yield in maize. Cytokinins are well reported for reducing the perilous effects of drought stress in maize (Zea mays L.). A net house study was planned to compare the efficacy of synthetic cytokinins, benzyl amino purine (BAP) with a natural source of cytokinins i.e., leaf extract of Moringa olifera as foliar application on maize seedlings subjected to different levels of drought (75% & 50% of field capacity). On weekly basis, the plants were sprayed with BAP (50 mg L -1 ) and moringa leaf extract (MLE) (30 times diluted with water) @ 25 mL/plant. The Plants applied with normal irrigation (100% field capacity) and water spray were taken as control. The crop was analyzed for seedling vigor, growth, water relations, physiological attributes and enzymatic antioxidants. The results showed that drought stress significantly affected the leaf area, plant height; rooting density, root fresh and dry weights, shoot fresh and dry weights, cell membrane thermostability (CMT), leaf temperature, osmotic and turgor potentials, peroxidase (POD) activity and chlorophyll a contents. Foliar applications significantly improved the leaf area, plant height, root fresh and dry weights, CMT and chlorophyll a, b contents. BAP alleviated the drought stress better than other treatments as it increased the root fresh and dry weights, CMT, chlorophyll a and b contents significantly. MLE increased leaf area, plant height, chlorophyll a and b contents under severe drought stress (i.e., 50% field capacity) and root fresh and dry weights under mild stress. Under normal and mild drought stress levels, MLE found as a best stimulus for plant growth that triggered the physiological and biochemical attributes, while under severe drought stress BAP (50 mg L -1 ) gave the best results for mitigation of drought effects in maize. © 2011 Friends Science Publishers Key Words: Drought stress; Cytokinins; Chlorophylls; Cell membrane stability; Maize INTRODUCTION Maize is the third most important cereal after wheat and rice all over the world serving as staple food for many countries (Frova et al., 1999). In Pakistan, maize is grown on an area of 950,000 ha with the production of 3,487,000 tones and average grain yield of 3671 kg ha -1 (Government of Pakistan, 2010). Maize is cultivated in both spring and autumn seasons and it is best suited in existing cropping scheme. However, yield potential of maize is highly prone a biotic stresses (Drought, salinity, extreme temperatures, flooding, pollutants & poor or excessive irradiation) which are important factors towards limiting the crop productivity (Misovic, 1985; Lawlor, 2002). Among the abiotic stresses, drought is the most severe limitation to maize production (Sallah et al., 2002). To a careful estimate, only drought reasons for 50% or more reduction in average yields worldwide (Wang et al., 2003). Water stress reduces crop yield regardless of the growth stage at which it occurs (Jensen & Mogensen, 1984). Drought causes numerous physiological and biochemical changes in plants like reduced leaf size, stem extension, root proliferation, reduced water use efficiency (Farooq et al., 2009), alteration in metabolic activities (Lawlor & Cornic, 2002), inhibition of enzymatic activities (Ashraf et al., 1995), ionic imbalance and disturbances in solute accumulation (Khan et al., 1999) or a combination of all these factors. In maize, drought reduces leaf area, leaf chlorophyll contents, photosynthesis and ultimately lowers the grain yield (Athar & Ashraf, 2005). At flowering, drought widens the anthesis silking interval (ASI) in maize, which severely reduces the kernel set (Emeadeas et al., 2000). Under drought leaf senescence is also accelerated to decrease the canopy size (Moony & Duplesis, 1970) severely affecting the crop yield. However delayed leaf senescence affects positively for reducing the harmful effects of drought on crop yield (Rivero et al., 2007).