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Influence of
environmental variations on physiological attributes of
sunflower
Shuaib Kaleem1,
Fayyaz- ul- Hassan1 and Aamir Saleem2*
1Department
of Agronomy, PMAS-Arid Agriculture University, Rawalpindi,
Pakistan.
2Department
of Forestry and Range Management, PMAS-Arid Agriculture
University, Rawalpindi, Pakistan.
*Corresponding author. E-mail:
aamir_saleem2002@yahoo.com.
Tel.: +92-51-9290678.
Accepted 13 July, 2009 |
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High degree of adaptability, wide range of climatic
conditions, high photosynthetic capacity, maximum stomatal
conductance and efficient hydraulic mechanism allow
sunflower crop to be productive in broad range of
environments. Combined effects of environmental factors not
only modify plant phenology but also cause many
physiological changes. Field experiments, one each in spring
and autumn were conducted at Pir Mehr Ali Shah, Arid
Agriculture University Rawalpindi, Pakistan for 2 years
(2007 and 2008) to document the effect of environmental
variations on the physiological functions of sunflower
hybrids. Four sunflower hybrids, Alisson-RM, Parasio-24,
MG-2 and S-278 were planted in randomized complete block
design with 4 replications. The data on physiological
attributes like photosynthetic rate, stomatal conductance
and transpiration rate at 10 days interval after complete
emergence to 60 days after emergence (DAE) was recorded.
Overall higher values of photosynthetic rate, stomatal
conductance and transpiration rate were recorded during
spring as compared to autumn for both the years.
Photosynthates accumulation and utilization was depressed in
cold imposing a restriction on biomass production than at
warm temperature. Physiological performance of all the
hybrids during spring at the start was slower as compared to
autumn. Progressive increase in photosynthetic rate,
stomatal conductance and transpiration was recorded with the
gradual increase in temperature up to a certain level during
spring but further increase in temperature caused decline in
these attributes. However during autumn, values of all these
3 physiological attributes were higher at the start those
declined with gradual decrease in temperature later in the
season.
Key words:
Photosynthetic rate, stomatal conductance, transpiration
rate, temperature, varying environments. |
