EFFECTS OF WATER DEFICIT STRESS, SHADE, WEED COMPETITION, AND KAOLIN PARTICLE FILM ON SELECTED FOLIAR FREE AMINO ACID ACCUMULATIONS IN COTTON, GOSSYPIUM HIRSUTUM (L.)

Authors: Showler, Allan

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2001
Publication Date: 3/1/2002
Citation: Showler, A. 2002. Effects of water deficit stress, shade, weed competition, and kaolin particle film on selected foliar free amino acid accumulations in cotton, Gossypium hirsutum (L.). Journal of Chemical Ecology. 28(3):631-651.

Interpretive Summary: Two plant stresses, drought and shading, each caused free amino acids levels in cotton leaves to change. Those results were used to determine stress factors in play in cotton subjected to weed competition, and to cotton sprayed with a white mineral dust that might be useful in pest control.

Technical Abstract: This study was conducted to determine how various stresses and use of kaolin particle film for potential insect control could affect foliar levels of selected free amino acids that might be used for stress diagnostics in cotton. Leaves of cotton plants, Gossypium hirsutum L., stressed by water deficit, reduced daylight, and weed competition, or treated with kaolin particle film were analyzed for levels of 17 free amin acids (FAAs) using reversed phase high performance liquid chromatography. Water deficit stress resulted in heightened free proline levels (49.9-fold, P < 0.0001) which were correlated with diffusive resistance of leaf stomates. Five other FAAs increased with water deficit stress, and the amounts of total free essential (for insect growth and development) amino acids and total FAAs also increased (P less than or equal to 0.05). Cotton grown in 50% shade accumulated significantly more free arginine than control plants. The responses of free proline and arginine to the treatments used in these assays demonstrate that types and degrees of some stresses (in this study, water deficit and shade) to cotton can be characterized by accumulation of certain FAAs (in this study, proline and arginine) so that FAA accumulations associated with weed competition or application of kaolin particle film can be interpreted in terms of impinging stress factors. Porometry and leaf water pressure measurements assisted in corroborating the findings of this study.