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Pak. J. Bot., 47(6): 2223-2230, 2015.

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ASSESSMENT OF ECONOMIC BENEFITS OF FOLIARLY APPLIED OSMOPROTECTANTS IN ALLEVIATING THE ADVERSE EFFECTS OF WATER STRESS ON GROWTH AND YIELD OF COTTON (GOSSYPIUM HIRSUTUM L.)

SIBGHA NOREEN^2*, ZAFAR ULLAH ZAFAR¹, KAUSAR HUSSAIN¹, HABIB-UR-REHMAN ATHAR¹ AND M. ASHRAF²

¹Institute of Pure and Applied Biology, Bahauddin Zakariya University, Multan 60800, Pakistan

²Pakistan Science Foundation, Islamabad Pakistan

^*Corresponding author: sibgha_noreen@yahoo.com

Abstract: Water stress reduces crop growth and productivity by affecting various physiological and biochemical processes. Although foliar application of osmoprotectants alleviates the detrimental effects of drought stress growth and productivity of crops, its economic benefits on large scale has not been explored yet. The studies were carried out to quantify the interactive effects of some osmoprotectantsand various watering regimes on cotton crop. The treatments consisted of water stress and osmoprotectant applications [(a) two watering regimes (well watered, 2689m³ water; drought stressed, 2078m³), and (b) three osmoprotectants (untreated check; water spray containing 0.1 % Tween-80; salicylic acid (100 mg L^-1); proline (100 mg L^-1); glycine betaine (100 mg L^-1)] in split plot design. The crop was subjected to drought stress at day 45 after sowing, i.e., at the flowering stage. The solutions of osmoprotectants were foliarly applied after two weeks of imposition of water stress (at the peak flowering stage). The results showed that imposition of water stress caused substantial reduction in plant growth, biological yield, fruit production, and fiber characteristics as compared to fully irrigated cotton crop. However, the application of osmoprotectants was found effective in off-setting the negative impacts of drought stress. The exogenous application of salicylic acid (100 mgL^-1) caused improvement by 47.9%, 36.5%, 17.4%, 4.86% and 9.9% in main stem height, biological yield, fruit production, fiber length and seedcotton yield over an untreated check, respectively. The efficiency of various osmoprotectants was in order of salicylic acid > glycinebetaine > proline in alleviating the harmful effects of drought stress. The usage of osmoprotectants was also found most cost-effective and the value for money. The cost-benefit ratio was 1:9.1, 1:3.9 and 1:1.7 by spraying of salicylic acid, proline and glycinebetaine, respectively. The research study reveals that salicylic acid may be foliarly applied to sustain growth, productivity, fiber characteristics and ultimately accruing higher profits under water stress environment.

Key words: Exogenous application; Salicylic acid; Proline; Glycinebetaine; Fiber quality; Yield components.