Papers by Muhammad Farooq
Journal of Agronomy and Crop Science, 2008
Plant growth and development is hampered by various environmental stresses including chilling. We... more Plant growth and development is hampered by various environmental stresses including chilling. We investigated the possibility of improving chilling tolerance in hybrid maize by glycinebetaine (GB) seed treatments. Maize hybrid (Hycorn 8288) seeds were soaked in 50, 100 and 150 mg l−1 (p.p.m.) aerated solution of GB for 24 h and were dried back. Treated and untreated seeds were sown at 27 °C (optimal temperature) and at 15 °C (chilling stress) under controlled conditions. Germination and seedling growth was significantly hindered under chilling stress. Moreover, chilling stress significantly reduced the starch metabolism and relative water contents (RWC), and increased the membrane electrolyte leakage. However, activities of antioxidants (catalase, superoxide dismutase and ascorbate peroxidase) were increased under stress conditions. Seed treatments with GB improved the germination rate, root and shoot length, seedling fresh and dry weights, leaf and root scores, RWC, soluble sugars, α-amylase activity and antioxidants significantly compared with untreated seeds under optimal and stress conditions. Induction of chilling tolerance was attributed to maintenance of high tissue water contents, reduced membrane electrolyte leakage, and higher antioxidant activities and carbohydrate metabolism. Seed treatment with 100 mg l−1 GB was the best treatment for improving the performance of hybrid maize under normal and stress conditions compared with control and other levels used.
Plant Growth Regulation, 2006
Poor seedling establishment is a major deterrent in adopting direct seeding of rice. Seed priming... more Poor seedling establishment is a major deterrent in adopting direct seeding of rice. Seed priming to obtain better crop stand could be an attractive approach. The objective of this study was to determine the effectiveness of seed priming strategies on the improved agronomic characters of direct-sown rice. Seed priming strategies were: hydropriming for 48 h, osmohardening with KCl or CaCl2 for 24 h, ascorbate priming for 48 h and seed hardening for 24 h, pre-germination (traditional soaking for nursery raising) and untreated control. Seed priming improved germination and emergence, allometry, kernel yield, and its quality, whilst pre-germination displayed poor and erratic emergence of seedling followed by poor plant performance. Faster and uniform emergence was due to improved α-amylase activity, which increased the level of soluble sugars in the primed kernels. Osmohardening with KCl gave greater kernel and straw yield and harvest index, followed by that of CaCl2, hardening and ascorbate priming. Improved yield was attributed principally to number of fertile tillers and 1000 kernel weight. A positive correlation between mean emergence time and days to heading, while a negative one between kernel yield and harvest index suggested long-term effects of seed priming on plant growth and development. The results suggest that physiological changes produced by osmohardening enhanced the starch hydrolysis and made more sugars available for embryo growth, vigorous seedling production and, later on, improved allometric, kernel yield and quality attributes.
Plant Production Science, 2006
Higher water requirements and increasing labor costs are the major problems of the traditional ri... more Higher water requirements and increasing labor costs are the major problems of the traditional rice production system. To overcome these problems, aerobic or direct seeded rice culture, growing rice without standing water, can be an attractive alternate. However, poor emergence and seedling establishment, and weed infestation are the main hindrances in the adoption of this culture. An attempt to improve the performance of direct seeded rice by seed priming was made in a field trial. Priming tools employed were traditional soaking (soaking in tap water up to radicle protrusion), hydropriming for 48 h, osmohardening with KCl or CaCl 2 (ψs-1.25 MPa) for 24 h (one cycle), vitamin priming (ascorbate 10 ppm) for 48 h and seed hardening for 24 h. All the priming techniques improved crop stand establishment, growth, yield and quality except traditional soaking, which resulted in impaired germination and seedling establishment that ended in reduced kernel yield and lower harvest index than that of control. Early and synchronized germination was accompanied by enhanced amylase activity and total sugars. Osmohardening with CaCl 2 resulted in the best performance, followed by hardening and osmohardening with KCl.
Journal of Agronomy and Crop Science, 2008
The optimum temperature for maize germination is between 25 and 28 °C. Poor and erratic germinati... more The optimum temperature for maize germination is between 25 and 28 °C. Poor and erratic germination at suboptimal temperature is the most important hindrance in its early sowing. This study was conducted to induce chilling tolerance in hybrid maize (Zea mays L.) by seed priming with salicylic acid (SA) and to unravel the background biochemical basis. For seed priming, maize hybrid (Hycorn 8288) seeds were soaked in 50, 100 and 150 ppm (mg l−1) aerated solutions of SA for 24 h and were dried back. Treated and untreated seeds were sown at 27 °C (optimal temperature) and at 15 °C (chilling stress) under controlled conditions. Performance of maize seedlings was hampered under chilling stress. But seed priming with SA improved the seedling emergence, root and shoot length, seedling fresh and dry weights, and leaf and root score considerably compared with control both at optimal and chilling temperatures. However, priming in 50 mg l−1 SA solution was more effective, followed by priming in 100 mg l−1 SA solution. Seed priming with SA improved the chilling tolerance in hybrid maize mainly by the activation of antioxidants (including catalase, superoxide dismutase and ascorbate peroxidase). Moreover, maintenance of high tissue water contents and reduced membrane permeability also contributed towards chilling tolerance.
Agronomy for Sustainable Development, 2009
Scarcity of water is a severe environmental constraint to plant productivity. Drought-induced los... more Scarcity of water is a severe environmental constraint to plant productivity. Drought-induced loss in crop yield probably exceeds losses from all other causes, since both the severity and duration of the stress are critical. Here, we have reviewed the effects of drought stress on the growth, phenology, water and nutrient relations, photosynthesis, assimilate partitioning, and respiration in plants. This article also describes the mechanism of drought resistance in plants on a morphological, physiological and molecular basis. Various management strategies have been proposed to cope with drought stress. Drought stress reduces leaf size, stem extension and root proliferation, disturbs plant water relations and reduces water-use efficiency. Plants display a variety of physiological and biochemical responses at cellular and whole-organism levels towards prevailing drought stress, thus making it a complex phenomenon. CO2 assimilation by leaves is reduced mainly by stomatal closure, membrane damage and disturbed activity of various enzymes, especially those of CO2 fixation and adenosine triphosphate synthesis. Enhanced metabolite flux through the photorespiratory pathway increases the oxidative load on the tissues as both processes generate reactive oxygen species. Injury caused by reactive oxygen species to biological macromolecules under drought stress is among the major deterrents to growth. Plants display a range of mechanisms to withstand drought stress. The major mechanisms include curtailed water loss by increased diffusive resistance, enhanced water uptake with prolific and deep root systems and its efficient use, and smaller and succulent leaves to reduce the transpirational loss. Among the nutrients, potassium ions help in osmotic adjustment; silicon increases root endodermal silicification and improves the cell water balance. Low-molecular-weight osmolytes, including glycinebetaine, proline and other amino acids, organic acids, and polyols, are crucial to sustain cellular functions under drought. Plant growth substances such as salicylic acid, auxins, gibberrellins, cytokinin and abscisic acid modulate the plant responses towards drought. Polyamines, citrulline and several enzymes act as antioxidants and reduce the adverse effects of water deficit. At molecular levels several drought-responsive genes and transcription factors have been identified, such as the dehydration-responsive element-binding gene, aquaporin, late embryogenesis abundant proteins and dehydrins. Plant drought tolerance can be managed by adopting strategies such as mass screening and breeding, marker-assisted selection and exogenous application of hormones and osmoprotectants to seed or growing plants, as well as engineering for drought resistance.
Journal of Integrative Plant Biology, 2005
In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal h... more In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling; heating followed by chilling or chilling followed by heating). In indica rice, heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination, as well as increased germination index, energy of germination, radicle and plumule length, root length, root/shoot ratio, root fresh and dry weight, radicle and plumule growth rate, and shoot fresh weight. In japonica rice, chilling followed by heating followed by chilling performed better than all other treatments, including control.
Journal of Agronomy and Crop Science, 2008
Plant growth and development is hampered by various environmental stresses including chilling. We... more Plant growth and development is hampered by various environmental stresses including chilling. We investigated the possibility of improving chilling tolerance in hybrid maize by glycinebetaine (GB) seed treatments. Maize hybrid (Hycorn 8288) seeds were soaked in 50, 100 and 150 mg l−1 (p.p.m.) aerated solution of GB for 24 h and were dried back. Treated and untreated seeds were sown at 27 °C (optimal temperature) and at 15 °C (chilling stress) under controlled conditions. Germination and seedling growth was significantly hindered under chilling stress. Moreover, chilling stress significantly reduced the starch metabolism and relative water contents (RWC), and increased the membrane electrolyte leakage. However, activities of antioxidants (catalase, superoxide dismutase and ascorbate peroxidase) were increased under stress conditions. Seed treatments with GB improved the germination rate, root and shoot length, seedling fresh and dry weights, leaf and root scores, RWC, soluble sugars, α-amylase activity and antioxidants significantly compared with untreated seeds under optimal and stress conditions. Induction of chilling tolerance was attributed to maintenance of high tissue water contents, reduced membrane electrolyte leakage, and higher antioxidant activities and carbohydrate metabolism. Seed treatment with 100 mg l−1 GB was the best treatment for improving the performance of hybrid maize under normal and stress conditions compared with control and other levels used.
Plant Growth Regulation, 2006
Poor seedling establishment is a major deterrent in adopting direct seeding of rice. Seed priming... more Poor seedling establishment is a major deterrent in adopting direct seeding of rice. Seed priming to obtain better crop stand could be an attractive approach. The objective of this study was to determine the effectiveness of seed priming strategies on the improved agronomic characters of direct-sown rice. Seed priming strategies were: hydropriming for 48 h, osmohardening with KCl or CaCl2 for 24 h, ascorbate priming for 48 h and seed hardening for 24 h, pre-germination (traditional soaking for nursery raising) and untreated control. Seed priming improved germination and emergence, allometry, kernel yield, and its quality, whilst pre-germination displayed poor and erratic emergence of seedling followed by poor plant performance. Faster and uniform emergence was due to improved α-amylase activity, which increased the level of soluble sugars in the primed kernels. Osmohardening with KCl gave greater kernel and straw yield and harvest index, followed by that of CaCl2, hardening and ascorbate priming. Improved yield was attributed principally to number of fertile tillers and 1000 kernel weight. A positive correlation between mean emergence time and days to heading, while a negative one between kernel yield and harvest index suggested long-term effects of seed priming on plant growth and development. The results suggest that physiological changes produced by osmohardening enhanced the starch hydrolysis and made more sugars available for embryo growth, vigorous seedling production and, later on, improved allometric, kernel yield and quality attributes.
Plant Production Science, 2006
Higher water requirements and increasing labor costs are the major problems of the traditional ri... more Higher water requirements and increasing labor costs are the major problems of the traditional rice production system. To overcome these problems, aerobic or direct seeded rice culture, growing rice without standing water, can be an attractive alternate. However, poor emergence and seedling establishment, and weed infestation are the main hindrances in the adoption of this culture. An attempt to improve the performance of direct seeded rice by seed priming was made in a field trial. Priming tools employed were traditional soaking (soaking in tap water up to radicle protrusion), hydropriming for 48 h, osmohardening with KCl or CaCl 2 (ψs-1.25 MPa) for 24 h (one cycle), vitamin priming (ascorbate 10 ppm) for 48 h and seed hardening for 24 h. All the priming techniques improved crop stand establishment, growth, yield and quality except traditional soaking, which resulted in impaired germination and seedling establishment that ended in reduced kernel yield and lower harvest index than that of control. Early and synchronized germination was accompanied by enhanced amylase activity and total sugars. Osmohardening with CaCl 2 resulted in the best performance, followed by hardening and osmohardening with KCl.
Journal of Agronomy and Crop Science, 2008
The optimum temperature for maize germination is between 25 and 28 °C. Poor and erratic germinati... more The optimum temperature for maize germination is between 25 and 28 °C. Poor and erratic germination at suboptimal temperature is the most important hindrance in its early sowing. This study was conducted to induce chilling tolerance in hybrid maize (Zea mays L.) by seed priming with salicylic acid (SA) and to unravel the background biochemical basis. For seed priming, maize hybrid (Hycorn 8288) seeds were soaked in 50, 100 and 150 ppm (mg l−1) aerated solutions of SA for 24 h and were dried back. Treated and untreated seeds were sown at 27 °C (optimal temperature) and at 15 °C (chilling stress) under controlled conditions. Performance of maize seedlings was hampered under chilling stress. But seed priming with SA improved the seedling emergence, root and shoot length, seedling fresh and dry weights, and leaf and root score considerably compared with control both at optimal and chilling temperatures. However, priming in 50 mg l−1 SA solution was more effective, followed by priming in 100 mg l−1 SA solution. Seed priming with SA improved the chilling tolerance in hybrid maize mainly by the activation of antioxidants (including catalase, superoxide dismutase and ascorbate peroxidase). Moreover, maintenance of high tissue water contents and reduced membrane permeability also contributed towards chilling tolerance.
Agronomy for Sustainable Development, 2009
Scarcity of water is a severe environmental constraint to plant productivity. Drought-induced los... more Scarcity of water is a severe environmental constraint to plant productivity. Drought-induced loss in crop yield probably exceeds losses from all other causes, since both the severity and duration of the stress are critical. Here, we have reviewed the effects of drought stress on the growth, phenology, water and nutrient relations, photosynthesis, assimilate partitioning, and respiration in plants. This article also describes the mechanism of drought resistance in plants on a morphological, physiological and molecular basis. Various management strategies have been proposed to cope with drought stress. Drought stress reduces leaf size, stem extension and root proliferation, disturbs plant water relations and reduces water-use efficiency. Plants display a variety of physiological and biochemical responses at cellular and whole-organism levels towards prevailing drought stress, thus making it a complex phenomenon. CO2 assimilation by leaves is reduced mainly by stomatal closure, membrane damage and disturbed activity of various enzymes, especially those of CO2 fixation and adenosine triphosphate synthesis. Enhanced metabolite flux through the photorespiratory pathway increases the oxidative load on the tissues as both processes generate reactive oxygen species. Injury caused by reactive oxygen species to biological macromolecules under drought stress is among the major deterrents to growth. Plants display a range of mechanisms to withstand drought stress. The major mechanisms include curtailed water loss by increased diffusive resistance, enhanced water uptake with prolific and deep root systems and its efficient use, and smaller and succulent leaves to reduce the transpirational loss. Among the nutrients, potassium ions help in osmotic adjustment; silicon increases root endodermal silicification and improves the cell water balance. Low-molecular-weight osmolytes, including glycinebetaine, proline and other amino acids, organic acids, and polyols, are crucial to sustain cellular functions under drought. Plant growth substances such as salicylic acid, auxins, gibberrellins, cytokinin and abscisic acid modulate the plant responses towards drought. Polyamines, citrulline and several enzymes act as antioxidants and reduce the adverse effects of water deficit. At molecular levels several drought-responsive genes and transcription factors have been identified, such as the dehydration-responsive element-binding gene, aquaporin, late embryogenesis abundant proteins and dehydrins. Plant drought tolerance can be managed by adopting strategies such as mass screening and breeding, marker-assisted selection and exogenous application of hormones and osmoprotectants to seed or growing plants, as well as engineering for drought resistance.
Journal of Integrative Plant Biology, 2005
In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal h... more In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling; heating followed by chilling or chilling followed by heating). In indica rice, heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination, as well as increased germination index, energy of germination, radicle and plumule length, root length, root/shoot ratio, root fresh and dry weight, radicle and plumule growth rate, and shoot fresh weight. In japonica rice, chilling followed by heating followed by chilling performed better than all other treatments, including control.
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Papers by Muhammad Farooq