Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/1997
Publication Date: N/A
Interpretive Summary: The colonization of cotton root systems by a group of beneficial soil fungi collectively known as mycorrhizae was evaluated under a range of management conditions. The levels of colonization in the cotton roots were higher when the cotton had been planted into winter wheat that had been terminated by spraying with herbicide in early April. The terminated wheat serves as a windbreak, minimizing the damage to cotton seedlings. Increased colonization of the cotton roots due to the presence of the wheat roots may contribute to seedling survival and improved seedling establishment under early season stress conditions.
Technical Abstract: Arbuscular-mycorrhizal colonization patterns of cotton (Gossypium hirsutum L.) growing under the range of management conditions that are employed for the production of this crop on the Southern High Plains of Texas were examined in 1991 and 1992. The mycorrhizal development of cotton grown under center-pivot irrigation, dryland, center-pivot irrigation of cotton planted into winter wheat, and row-irrigated cotton planted into terminated-winter wheat were evaluated. During 1991, colonization levels were highest for cotton planted into winter wheat. Furthermore, cotton planted into winter wheat developed more arbuscules and had higher levels of mycorrhizae earlier than any of the other production systems examined. During 1992, at 3 weeks after planting, about 5 days of cold, wet weather resulted in almost 100 percent mortality of cotton not previously planted into winter wheat. Mycorrhizal colonization levels were greater for cotton associated with winter wheat than for cotton grown under conventional practices. The higher colonization levels associated with young cotton plants that were grown with winter wheat vs. cotton under conventional tillage practices suggests that AM-inoculum levels may have been higher prior to planting in the cotton+wheat management system for both the 1991 and 1992 studies. The maintenance of a hyphal network for developing cotton seedling may be crucial to allow cotton to become colonized rapidly during the seedling stage. Cotton seedling establishment on the Southern High Plains is a critical time for this crop due to abiotic stress, such as high or low temperatures and inadequate moisture, and any benefit from the symbiosis at this time should have a positive impact on yields.