Nitrogen Fertility and Planting Date Effects on Lint Yield and CRY1AC(BT) Endotoxin Production

Authors: Pettigrew, William; Adamczyk, John

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 10/26/2004
Publication Date: 1/4/2005
Citation: Pettigrew, W.T., Adamczyk Jr, J.J. 2005. Nitrogen Fertility and Planting Date Effects on Lint Yield and CRY1AC(BT) Endotoxin Production [abstract]. National Cotton Council Beltwide Cotton Conference.

Interpretive Summary:

Technical Abstract: While the new early planting cotton production system offers improved yield potential relative to a more traditional planting date, the actual production nuances still need to be optimized to consistently maximize yield production. For instance, with additional nitrogen, could the early planting system take advantage of its longer growing season to produce even greater yields via a larger top crop. To test this hypothesis, four nitrogen fertility treatments (100/50 lbs liquid N per acre split applications, 100 lbs liquid N per acre preplant, 50/50 lbs liquid N per acre split applications, and 100 lbs anhydrous ammonia N per acre preplant) were imposed upon three cotton genotypes, two of which contained the gene (Cry1Ac) for expression of the Bt endotoxin during the 2003 and 2004 growing seasons at Stoneville, MS. Two planting dates, early April and early May, were also utilized in the study. Lint yield, yield components, fiber quality, dry matter production, leaf chlorophyll (Chl) concentration, and leaf Bt endotoxin concentrations were determined each year. Leaves from both planting dates were sampled on the same days for the leaf Chl and Bt endotoxin concentration determinations. Lint yield was not altered by the various N fertility treatments in 2003. The additional N from the 150 lbs total N per acre elevated the Bt endotoxin expression 12% relative to the treatments that only received 100 lbs total N per acre. The 150 lbs total N per acre treatment also elevated the leaf Chl concentration 3% relative to the 100 lbs total N per acre treatment. Leaf Bt endotoxin levels in cotton planted during early April were 14% lower than levels found in cotton planted in early May, presumably due to remobilization of the leaf N to support the larger developing boll load in the early April planted cotton. The data from this study demonstrate that expressions levels of transgenic traits are under both genetic and environmental control, as are all traits. This environmental component can be influenced by production practices, to the same degree that any of these practices alter the growing environment.