Abstract
Many environmental stress factors have been identified to increase square and boll abscission and thus result in reduced cotton yield. Under stress conditions, ethylene is elicited. Ethylene peaks before abscission to promote the formation of the abscission layer and plays a major role in early season square and boll abortion in cotton (Gossypium hirsutum L.). In addition, ethylene stimulates the leaf senescence process. Thus, it is desirable to protect plants from ethylene-induced fruit loss and premature leaf senescence under stress conditions. The objective of this study was to evaluate the ability of 1-methylcyclopropene (1-MCP) to protect cotton plants against abiotic stress caused by ethephon (ethylene promoting effect). Field studies using a randomized complete block design with four replications were conducted in 2010 and 2011 at Texas A&M AgriLIFE Research Farm in Burleson County, TX. Eight treatments that consisted of two 1-MCP rates (0 and 10 g a.i. ha-1) in combination with four ethephon rates (0, 146, 292, 438 mL·ha-1) were imposed at the first flower (FF) stage of the development. 1-MCP increased plant height and number of main stem nodes in both years. In addition, 1-MCP-treated plants exhibited greater membrane integrity and increased photosystem II quantum efficiency and thus delayed senescence in both years. These potentials for yield increase were realized in 2011 with 1-MCP treatment exhibiting a higher lint yield. In 2012, although 1-MCP treatment increased number of open fruit and open fruit weight per plant significantly, no significant lint yield increase was detected.
Highlights
Ethylene plays a primary role in the abscission of leaves [1]-[3] and fruit [4]
Because we found that 1-MCP works more efficiently in stress conditions, our present study was designed to test effect of 1-MCP under different stress levels applied as different rates of ethephon in the field conditions by assessing leaf senescence traits and yield related data
The greatest contribution to this increase of yields was from 1-MCP treatment under the ethephon rate of 292 mL∙ha−1. 1-MCP plus 292 mL∙ha−1 ethephon treatment increased lint yield by 18% compared to 292 mL·ha−1 ethephon treatment alone
Summary
Ethylene plays a primary role in the abscission of leaves [1]-[3] and fruit [4]. Because boll retention is a major concern for cotton yield improvement, the role of ethylene in cotton fruit shedding has been studied extensively. Ethylene promotes the abscission layer formation in the peduncle in cotton plants, leading to fruit abortion [4]. Research has demonstrated that ethylene production plays a major role in early season square and boll abortion [4]-[7]. Stresses may further decrease boll retention as confirmed by the fact that ethylene production accelerates induction of fruit shed of cotton plants under drought [2] [5] [10]. Due to the crucial role that ethylene plays in square and boll loss, it is advantageous to protect plants from ethylene-induced fruit loss
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