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Pak. J. Bot., 42(4): 2541-2550, 2010. |
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Updated: 09-12-10 |
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LOWER AND UPPER BASELINES FOR CROP WATER STRESS INDEX AND YIELD OF GOSSYPIUM HIRSUTUM L. UNDER VARIABLE IRRIGATION REGIMES IN IRRIGATED SEMIARID ENVIRONMENT
M. USMAN1*, M. ARSHAD1, A. AHMAD2, N. AHMAD1, M. ZIA-UL-HAQ3, A. WAJID2, T. KHALIQ2, W. NASEEM2, Z. HASNAIN, H. ALI3 AND S. AHMAD3*
Abstract: Cotton (Gossypium hirsutum L.) is an important cash
crop of Pakistan. The study regarding determination of lower and upper
base lines for crop water stress index (CWSI) for cotton was conducted
during summer, 2006 at Post Agricultural Research Station, University of
Agriculture, Faisalabad situated at latitude 31°25΄N, longitude 73°09΄E
and altitude 184.4 m from sea level. Experiment comprised of five
treatments of irrigation levels replicated thrice under randomized
complete block design. Vapor pressure deficit (VPD) was also measured
for this purpose. Upper baseline was established by growing a separate
treatment T5 without any irrigation or excessive rainfall.
While lower baseline was established by using air and canopy temperature
attained on clear sunny days within 5-8 days of irrigation and rainfall
application. Effect of treatments on leaf area index (LAI) was observed
and a relationship was established between yield and LAI. The
relationship between yield and seasonal mean CWSI was found to be
linear. No significant differences were found in yield of treatments T3
and T4, suggesting that an extra irrigation may be saved in
treatment T4 without any significant loss in yield. Water
use efficiency (WUE) was found non significant among different
irrigation treatments with overall mean value of 0.54 kg m-3. 1Department of Irrigation and Drainage, 2Agro-Climatology Laboratory, University of Agriculture, Faisalabad- 38040, Pakistan 3Department of Agronomy & Chemistry, Bahauddin Zakariya University, Multan-60800, Pakistan *Corresponding author E-mail: shakeel.agronomy@googlemail.com |
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