Location: Crop Production Systems Research2012 Annual Report
1a. Objectives (from AD-416):
1: Develop sustainable management strategies for cotton, corn, soybeans and other crops grown in the mid-southern United States, and determine the impact of crop rotations, tillage, and herbicide regimes on crop physiology and weed control options. 2: Evaluate the impact of crop management on quality traits of various crops in the system, including cotton (gossypol, boll development, maturity, length, strength, and uniformity) and soybean (fatty acid profiles and protein quality).
1b. Approach (from AD-416):
Conventional corn hybrids and transgenic corn hybrids containing insect and herbicide resistance traits will be compared for variation in physiological components, mycotoxin contamination, insect damage, agronomic performance and economic return. Maturity group IV and V soybean varieties will be grown in both twin-row and single row planting patterns to compare their growth, photosynthesis, and agronomic performance. Glyphosate resistant corn hybrid grown in both twin-row and single row planting patterns will be evaluated for canopy light interception, photosynthesis, weed population densities, and agronomic performance. Conventional and glyphosate-resistant cotton-soybean rotation will be initiated under minimum tillage to assess impact on various soil properties, weed population densities, plant nutrition, cotton physiology, seed composition, crop agronomic performance, and economic return. Barnyardgrass and junglerice populations will be surveyed at various sites within the mid-southern region of the U.S. and characterized for morphological diversity and variation in growth parameters. Weed populations will be monitored throughout the growing season in glyphosate resistant soybeans grown in twin-row pattern to address issues with late season weed control. Different crop management systems for corn, cotton, and soybeans will be utilized on land infested with cogongrass to determine effectiveness and economic viability of various cogongrass control options. Obsolete and modern cotton varieties consisting of both conventional and transgenic types will be grown at two different plant population densities and assessed for variation in dry matter partitioning, canopy light interception, growth analysis, and agronomic performance. Diverse cotton varieties grown under either irrigated or dryland conditions and with 3 different levels of nitrogen fertilization will be assessed for dry matter partitioning, canopy light interception, chlorophyll fluorescence, and agronomic performance. Normal, okra, and super-okra leaf type isolines in the same genetic background will be grown in both twin-row and single row planting patterns and assessed for dry matter partitioning, canopy light interception, growth analysis, and agronomic performance.
3. Progress Report:
The results from the agronomic, physiological, and crop culture studies gave insight to physiological mechanisms leading to lint yield and fiber quality differences among diverse cotton varieties. A uniform population density of 1.5 cotton plants per foot either yielded higher than or the same as 3 plants per foot across all varieties. Variety, nitrogen rate, and irrigation regimes all individually impacted and interacted to affect lint yield, fiber quality, and seed composition. Twin-row cotton yielded the same as single row cotton regardless of the leaf shape in the first year of a study. The second year of an experiment examining the agronomic and economic value of stacked-gene corn hybrids is currently underway with photosynthesis data collection having been completed. The second year of a study examining the growth rates and nutrient uptake of three soybean cultivars of differing maturity is underway with data collection on photosynthesis and dry matter accumulation nearing completion. Twin-row and single-row irrigated corn with varying seeding rates nitrogen fertility rates were compared for yield and yield components during two growing seasons. Yields did not differ between the twin- or single-row treatments.
1. Twin-row corn production under varying plant populations and N fertility rates. Twin-row planting of corn and soybean are being readily adopted in the Mid South with the idea that such plantings yield more than conventional single-row seeds. However, information on its management needs and effects on crop yields is limited. A study comparing corn planted in 67,000, 80,000, 91,000, and 102,000 plants per hectare, grown at nitrogen fertility rates of 216, 264, and 312 kg of N/ha, and in both 20 cm twin-rows space on 102 cm centers and single-rows space 102 cm apart was completed by an ARS scientist at Stoneville, MS. That season the twin-row plantings yielded only slightly more grain. Final stands did not differ between row types and kernel weights were not influenced by row type or nitrogen fertility.
2. Cotton irrigation and nitrogen fertilization. Cotton producers are interested in making the most efficient use of their irrigation and nitrogen (N) fertilization inputs because although they are important inputs for a cotton production, these inputs can also be quite expensive. An ARS scientist at Stoneville, MS, has demonstrated that including irrigation is an important component to ensure the most efficient use of the nitrogen that is applied to cotton. In the 2011 growing season, the lint yield of non-irrigated cotton was not improved when 100 lbs N/acre was applied over the non-fertilized (858 vs. 813 lbs/acre). However, when irrigation was applied, the 100 lbs N/acre treated yielded 19% greater than the unfertilized (1,202 vs. 1,013 lbs/acre). Fiber quality and seed composition were also affected by the irrigation and nitrogen fertility treatments. Using this information producers will be in a better position to make a more appropriate N fertilization rate decision for a field depending upon the irrigation capabilities for that field.
3. Weed control and yield comparisons of glyphosate-resistant and glufosinate-resistant corn grown continuously and in rotation. Glyphosate-resistant and glufosinate-resistant corn weed management systems have both advantages and limitations. Scientist at Crop Production Systems Research Unit, Stoneville, Mississippi, conducted a 6-yr field study to determine the effects of rotating glyphosate-resistant and glufosinate-resistant corn under reduced tillage conditions on weed control, soil weed seedbank, and yield. The four rotation systems were glyphosate-resistant (RRRRRR) and glufosinate-resistant (LLLLLL) corn grown continuously and in rotation (RLRLRL and LRLRLR) with two herbicide programs, postemergence-only herbicides (POST) and preemergence herbicides followed by POST (PRE + POST). Control of 13 predominant weed species in glyphosate-resistant and glufosinate-resistant corn was >95%, regardless of herbicide program with the exception of johnsongrass and yellow nutsedge. Johnsongrass and yellow nutsedge control was lower in continuous LLLLLL system compared to other rotation systems. Corn yields were similar regardless of rotation. The PRE + POST program gave higher yield than POST-only program in 4 of 6 years. Seedbanks for grasses and yellow nutsedge were higher in the POST-only program compared to the PRE + POST program. These results indicate that johnsongrass and yellow nutsedge control could be reduced in continuous glufosinate-resistant corn and could be mitigated by rotating with glyphosate-resistant corn.Pettigrew, W.T., Dowd, M.K. 2012. Interactions between irrigation regimes and varieties result in altered cottonseed composition. Journal of Cotton Science. 16:42-52.