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Pak. J. Bot., 47(6): 2085-2091, 2015.

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SCREENING OF COTTON (GOSSYPIUM HIRSUTUM L.) GENOTYPES FOR HEAT TOLERANCE

SAIFULLAH ABRO^1*, MUHAMMAD TAHIR RAJPUT³, MUHAMMAD ATHAR KHAN¹ MAHBOOB ALI SIAL¹ AND SYEDA SALEHA TAHIR²

¹Nuclear Institute of Agriculture (NIA) Tando Jam, Sindh, Pakistan

²Institute of Plant Sciences, University of Sindh, Jamshoro, Sindh, Pakistan

³Preston University, 15 Banglore Town, Main Shahrah-e-Faisal, Karachi, Pakistan

^*Corresponding author e-mail: saif_sabro@yahoo.com

Abstract: Cotton yield is highly affected due to biotic (diseases and pests) and abiotic (heat, dought and salinity) Stresses. Among them, high temperature is the main environmental constraint which adversely reduces cotton yield and quality. High temperature above 36^oC affects plant growth and development especially during reproductive phase. Present studies were carried out to assess the tolerance of fifty-eight newly evolved cotton genotypes to heat stresses, based on agronomic and physiological characteristics.  The genotypes were screened in field conditions under two temperature regimes.  The studies were conducted at experimental farm of Nuclear Institute of Agriculture, Tando Jam, Pakistan. The results showed that March sown crop experienced high temperature (i.e. > 44^oC in May and June), which significantly affected crop growth and productivity. The genotypes were identified as heat-tolerant on the basis of relative cell injury percentage (RCI %), heat susceptibility index (HSI) values, boll retention and seed cotton yield (kg/ha). RCI level in cotton genotypes ranged from 39.0 to 86.0%. Out of 58, seventeen genotypes (viz.NIA-80, NIA-81, NIA-83, NIA-84, NIA-M-30, NIA-M31, NIA-HM-48, NIA-HM-327, NIA-H-32, NIA-HM-2-1, NIA-Bt1, NIA-Bt2, NIA-Perkh, CRIS-342, CRIS-134, NIAB-111 and check variety Sadori indicated high level of heat tolerance at both (heat-stressed and non-stressed) temperature regimes; as shown the lowest relative injury level and relatively heat resistant index (HSI<1) values. Such genotypes could be used as heat-tolerant genotypes under heat-stressed environments.

Key words: Cotton, Gossypium hirsutum L., High temperature tolerance, Cell Membrane-Thermostability (CMT).