Influence of Heat Units on Defoliation, Physiology and Yield of Cotton during Defoliants Application

Main Article Content

P. Chandrasekaran
V. Ravichandran
T. Sivakumar
A. Senthil
L. Mahalingam
N. Sakthivel


Aims: A study was conducted to determine the effect of temperature on defoliation process, physiology and yield of cotton during defoliants application.

Study Design: The experiment was laid out in split-plot design with four replications.

Place and Duration of Study: Field experiment was conducted at Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore during 2018 to 2019.

Methodology: The main plot comprised of three stage of defoliants spray (120 DAS, 127 DAS and 134 DAS) and the sub-plots were seven defoliant treatments (Control, 2, 4 D (0.5%), Ethephon (0.5%), Ethephon (0.5%) + Triiodbenzoic acid (TIBA) (450 ppm), Sodium chlorate (0.9%), 6 benzylaminopurine (BAP) (0.1%), Thidiazuron + Diuron (0.03%).

Results: After 15 days of defoliants spray, Thidiazuron + Diuron (0.03 %) recorded highest defoliation percentage (99.3, 98.1 and 96.8%) followed by Sodium chlorate (0.9 %) (91.9, 94.6 and 93.6%) at three different stage of defoliants spray. Although a significant effect was observed on chlorophyll index value (SPAD) due to the favorable weather condition like minimum temperature of 14.3, 16.9 and 19.3°C and maximum average temperature of 30.8, 31.8 and 33.23°C (120, 127 and 134 DAS respectively) during defoliants spray to 15 days after defoliants spray. Sodium chlorate (0.9%) and 6-BAP (0.1%) recorded higher (95.8 and 95.4) per cent boll opening at 120 DAS when comparing to 127 DAS and 134 DAS. Heat units accumulated during defoliants spray to 15 days after defoliants spray was 113.54, 140.52 and 169.57°C days (120, 127 and 134 DAS respectively).

Conclusion: Therefore, the minimum and maximum temperatures of 14.3 and 33.3°C, respectively conducive for inducing defoliation process and boll opening in cotton.

Boll, cotton, defoliants, temperature, heat units.

Article Details

How to Cite
Chandrasekaran, P., Ravichandran, V., Sivakumar, T., Senthil, A., Mahalingam, L., & Sakthivel, N. (2020). Influence of Heat Units on Defoliation, Physiology and Yield of Cotton during Defoliants Application. International Journal of Environment and Climate Change, 10(10), 77-84.
Original Research Article


Mishra A, Khare S, Trivedi PK, Nath P. Effect of ethylene, 1-MCP, ABA and IAA on break strength, cellulose and polygalacturonase activities during cotton leaf abscission. S Afr J of Bot. 2004; 74:282–287.

Wang G, Norton R. Choosing harvest aid chemicals for Arizona Cotton. Harvest aid materials and practices for California cotton. The Cotton Foundation, Publisher Memphis, Tennessee, USA; 2012.

Ayala F, Silvertooth JC, Tucson AZ. Physiology of cotton defoliation. University of Arizona Publication AZ; 2001.

Copur O, Demrel U, Karakus M. Effects of several plant growth regulators on the yield and fiber quality of cotton (Gossypium hirsutum L.). Not Bot Horti Agrobo. 2010; 38-3:104-110.

Mrunalini K, Sree Rekha M, Murthy VRK. Effectiveness of harvest – Aid defoliants and environmental conditions in high density cotton. Int. J. Curr. Microbiol. App. Sci. 2018;7(02): 2312-2316.

Chandrasekaran P, Ravichandran V, Senthil A, Mahalingam L, Sakthivel N. Effect of different defoliants and time of application on defoliation percentage and boll opening percentage in high density cotton (Gossypium hirsutum L.) Int. J. Plant & Soil Sci. 2020;32(10): 37-45.

Monje OA, Bughree, B. Inherent limitation of non-destructive chlorophyll meters. A comparison of two types of meters. Hort. Sci. 1992;(27):71-89.

Gomez KA, Gomez AA. Statistical procedures for agricultural research (2 ed.). John wiley and sons, NewYork. 1984; 680.

Cathey GW. Physiology of defoliation in cotton production. Cotton physiology. 1986;1:143-53.

Wright SD, Hutmacher RB, Shrestha A, Banuelos G, Rios S, Hutmacher KA, Munk DS, Keeley MP.). Impact of early defoliation on california pima cotton boll opening, lint yield, and quality. J. Crop Improv. 2015;29:528–541.

Jin D, Wang X, Xu Y, Gui H, Zhang H, Dong Q, Sikder RK, Yang G, Song M. Chemical defoliant promotes leaf abscission by altering ros metabolism and photosynthetic efficiency in Gossypium hirsutum. International journal of molecular sciences. 2020;21(8):2738.

Malik MN, Din S. Efficacy of thidiazuron defoliant in cotton cultivars varying in maturity. Pak Cottons. 1997;41:36-42.

Du MW, Ren XM, Tian XL, Duan LS, Zhang MC, Tan WM, Li ZH. Evaluation of harvest aid chemicals for the cotton-winter wheat double cropping system. J Integr Agric. 2013;12(2):273-82.

Singh T, Brar ZS, Prakash R, Hassan H. Effect of dates of planting and defoliant on yield and quality of cotton (Gossypium hirsutum L). J Cotton Res and Dev. 2003; 17(2):146-49.