The production of extrafloral nectar by cotton had two distinct peaks with cultivar 'Stoneville 7A,' the first peak produced by mainstem node leaf nectaries and the second peak produced by subbracteal nectaries on fruiting structures. Cultivar 'Coker 201 ' produced a first peak corresponding with that observed for 'Stoneville 7A,' and a much less pronounced but corresponding second peak. Oviposition by Heliothis puncti8era Wallengren moths was highly correlated with extrafloral nectar production during the first 13 weeks of the crop's development but poorly correlated later in the plant's development. It is postulated that the low correlation late season may be due to any of several factors, including a change in nectar quality or buildup of fungi associated with the nectaries.
The nectariless, near-isogenic cultivar of 'Stoneville 7A' produced a higher yield than its nectaried counterpart due to: (I) an intrinsically greater yield potential. and (2) a reduced attractiveness to insect pests which resulted in a reduction in pest damage. The greatest yield advantage occurred with the unsprayed field comparison where the nectariless cultivar had ca. 40% less damaged fruit over each of the 4 years. The nectariless cultivar also matured earlier, as much as 18 days with the unsprayed field comparison. The reduction in pest damage and earlier maturity for the nectariless cultivar has considerable significance for cotton crop production.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.