'Terminal heat stress in barley'
Ph.D 2nd Semester
University of Agriculture, Faisalabad, Pakistan
Supervisor Name: Prof. Dr. Riaz Ahmad
Barley is a rabbi cereal grain crop
Ranked 4th in cereal
Locally called ‘jao’(Urdu)
Old English word “Beare”
Latin word farina "flour"
Diploid with 14 chromosome
Inflorescence is spike
Has short duration than wheat
• Hordeum distichum L.
• Two-rowed barley
• Non shattering spikes
• Hordeum vulgare L.
• Six-rowed barley
• Non shattering
Heat stress is defined as the rise in temperature beyond a
threshold level for a period of time sufficient to cause
irreversible damage to plant growth and development (Wahid
et al. 2007) .
• Heat stress due to high ambient temperatures is a serious threat to
crop production worldwide (Hall, 2001).
• High temperature reduces duration of grain filling stages thereby
lowering the grain yield (Tiwari and Tripathy, 1999).
• Gawith (1999) reported optimal temperatures for grain filling as
residing between 19.3◦C and 22.1◦C.
• Despite impressive increases in wheat production after the
Green Revolution, terminal heat caused by high temperatures
during kernel development has emerged as a major threat to
wheat production (Rane et al., 2007).
• The staple cereal crops can tolerate only narrow temperature
ranges, which if exceeded during the flowering phase can damage
fertilization and seed production, resulting in reduced yield (Porter,
• Furthermore, high temperatures during grain filling can modify
flour and bread quality and other physico-chemical properties of
grain crops (Wardlaw et al., 2002).
• Rising temperatures may lead to altered geographical distribution and
growing season of agricultural crops by allowing the threshold
temperature for the start of the season and crop maturity to reach
earlier (Porter, 2005).
• Plants may be damaged by high day or high night temperatures and
by either high air or high soil temperatures.
• Global warming
• Global mean temperature will rise 0.3 0C per decade
(Intergovernmental panel on climate change, IPCC)
Morphological Symptoms of Heat stress
• Necrosis on leaves
• Scorchy appearance of leaves
• Reduction in leaf size
• White spots due to chlorophyll destruction
• Leakage of sap make more prone to pathogen attack
• Sunburn on leaves, stems and branches
• Fruits discoloration and damage
Impairment of pollen and anther development
Temperature can modify flour and bread quality
• Leaf senescence
• Water relations
• Grain growth and development
• Grain quality
Mechanism of Injury
• Protien denaturation
• Respiration (Doubles for every 10 0C)
• Photosynthesis (In C3 plants affected above 350C)
• Production of ROS
• Heat induced Drought
• Starvation (More respiration than Photosynthesis)
(Wahid et al., 2007)
How Photosynthesis affected
Farooq et al., 2011:Critical Reviews in Plant Sciences, 30:491–507, 2011
• Heat tolerance is generally defined as the ability
of the plant to grow and produce economic yield
under high temperatures.
Mechanism of Heat tolerance
• Transpiration as a coolant
• Structural adaptation
• Molecular basis
Agronomic management strategies
• Practices that conserve water
• Fertilization during critical growth stages and
timing of sowing
• Time of sowing: Early planting may avoid terminal
• Wahid. T., S. Gelani, M. Ashraf, M.R. Foolad. 2007. Heat tolerance in plants: An
overview. Environ. Exp. Bot. 61: 199-223.
• Hall, A.E., 2001. Crop Responses to Environment. CRC Press LLC, Boca Raton,
• Tewari, A.K. and B.C. Tripathy, 1999. Acclimation of chlorophyll biosynthetic
reactions to temperature stress in cucumber (Cucumis sativus L.). Planta, 208:
• Streck, N.A., 2005. Climate change and agroecosystems: the effect of elevated
atmospheric CO2 and temperature on crop growth, development and yield.
Ciência Rural, 35: 730–740.
• Asthir, B. R. Thapar, M.Farooq and N.S. Bains. 2013.Exogenous application of
thiourea improves the performance of late ssown wheat by inducing terminal heat
stress. Int. J. Agric. Biol. 15: 1337-1342.
• Porter, J.R., M. Gawith. 1999. Temperatures and the growth and development of
wheat: a review. European Journal of Agronomy 10: 23–36.
• Gate, P., Brisson, N., 2010. Advancement of phenological stages and shortening
of phases. In: Brisson, N., Levrault, F. (Eds.), Climate change, agriculture and
forests in France: simulations of the impacts on the main species. The Green
Book of the CLIMATOR project (2007–2010). ADEME, Angers, France, 65–78.
• Rane, J., Pannu, R.K., Sohu, V.S., Saini, R.S., Mishra, B., Shoran, J., Crossa,
J., Vargas, M., Joshi, A.K., 2007. Performance of yield and stability of advanced
wheat geno-types under heat stressed environments of Indo-Gangetic plains. Crop
• Joshi, M. 2007. Performance of yield and stability of advanced wheat geno-types
under heat stressed environments of Indo-Gangetic plains. Crop Sci. 47, 1561–
• Porter, J.R., 2005. Rising temperatures are likely to reduce crop yields. Nature . 436:
• Hadith. Volume 7, Book 71, Number 593: (Narrated 'Ursa)
• Kobata, T., Palta, J. A., and Turner, N. C. 1992. Rate of development of post anthesis water
deficits and grain filling of spring wheat. Crop Sci. 32: 1238–1242.
• Streck, N. A. 2005. Climate change and agroecosystems: the effect of elevated
atmospheric CO2 and temperature on crop growth, development and yield. Ciencia
• Yang, J., Sears, R. G., Gill, B. S., and Paulsen, G. M. 2002. Geno-ypic differences in
utilization of assimilate sources during maturation of wheat under chronic heat and heat
shock stresses.Euphytica125: 179–188.
• Zhao, H., Dai, T. B., Jing, Q., Jiang, D., and Cao, W. X. 2007. Leaf senescence and grain
filling affected by post-anthesis high temperatures in two different wheat cultivars. Plant
Barley Aurical without
Wheat Aurical With Wilde Oat without Aurical