2012 Annual Report
1a.Objectives (from AD-416):
Develop management practices for pest control in cotton. Evaluate and develop elite cotton germplasm for yield, quality and pest resistance. Develop improved agronomic practices for cotton production in an environment of changing technology.
1b.Approach (from AD-416):
Determine response of pests to available control practices. Evaluate response of cotton to management practices such as planting date, fertility practices and plant growth control. Measure pest response to application of control measures. Develop elite cotton germplasm and measure response in state yield tests. Transfer genes for resistance to diseases, insects and nematode into Delta-type cotton using traditional and molecular-assisted practices. Test alternative means to control pests with tolerance to normal control practices.
A series of three trials in different locations were conducted comparing the efficacy of seed treatment nematicides-insecticides to manage the reniform nematode. A trial was conducted to determine the response of 18 cotton varieties to the biological nematicide Votivo. All trials were conducted, stand counts were made, nematode samples were taken, and the trials were harvested. The data has been summarized.
A primary project objective is to release breeding lines with high yield, good fiber properties, and resistance to reniform nematodes (RN). Breeding lines were developed by crossing reniform nematode immunity/resistance from LONREN, GB713 and other sources (Gossypium G. barbadense derivatives) and root-knot (RK) nematode resistance into Mississippi Agricultural and Forestry Experiment Station (MAFES) breeding lines via conventional plant breeding protocols. Leaf samples from individual plants are screened via marker-assisted selection (MAS) (public domain markers) to identify reniform nematode and root-knot nematode resistant plants within plants identified. Tests included were: .
1)Three F3 RKN populations resulting from crosses with RN96425 and RN96527, RK nematodes resistant germplasm lines;.
2)F2 Lonren populations resulting from 2010 crosses and F1’s from Mexico and greenhouse for MAS;.
3)189 F2/F3 Lonren populations from 2010 segregating populations for MAS and homogeneity testing. Twenty plants of heterozygous populations were tagged per plot for MAS, and ten plants per plot in the homozygous populations were tagged to test for homogeneity;.
4)Crossing block to continue development of reniform and root knot nematode populations; and.
5)two yield trials from advanced reniform resistant lines were planted May 31, 2011, in field 12, Stoneville, MS. One trial consisted of 4 checks and 32 high quality or/and yield lines and second trial consist of 6 checks and 37 good fiber quality and yield lines based on the results of 2010. Total of 5,890 plants representing 3,480 F2 plants and 1,200 F2F3 plants tagged for individual plant selection, and 1,210 F2F3 plants from progeny rows for testing homogeneity were tagged for MAS. 248 individual plants were selected based on the presence of the RN and/or RK markers and yield potential. Selections will be planted for further testing for homogeneity, yield and fiber evaluation. Weight/plant and lint percent are very variable. F2 lint percent is generally low ranging from 27.1 to 43.9. 129 nematode resistant populations were tested for homogeneity. Unfortunately, 43% of these populations were not homogeneous ranging from zero to 70% of the plants tested not having the Lonren marker, and 15 of those populations had all of the 10 plants not having the marker. This is a major concern and is being investigated. Twenty-five breeding lines were selected to go forward based on homogeneity and field observations. Lint yield for the plot ranged from 1,346 pounds per acre (lb/a) to 530 lb/a with the parents averaging 832 lb/a. Eleven of the lines yielded over 1,000 lb/a. Thirty-two advanced lines selected based on high yield and fiber quality from 2010 with four checks were tested (Test A) in 2011 for a replicated yield trial. Nematode counts were above threshold throughout the season. Yields ranged from 1,314 lb/a to 653 lb/a with a test average of 787 lb/a. Most of the lines yielded higher than the commercial checks and similar lint percent. Test B included lines that in 2010 were good yield and average fiber quality. Yield ranged 1,024 lb/a to 590 lb/a with test average of 794 lb/a. Development of breeding lines/cultivars with resistance to both root-knot and reniform nematodes has been very successful but requires further testing. The goal of this project is to stack root-knot and reniform genes for resistance into a single genotype for the formal release of one or more root-knot/reniform nematode resistant breeding lines or varieties as quickly as possible to reduce cost of production to Mississippi cotton producers.
For the objective to evaluate efficacy of seed treatment nematicides on cotton which is resistant or susceptible to the reniform nematode, seed was obtained of breeding stock lines with known resistance to reniform nematode. Two advanced breeding lines with resistance conferred from G. barbadense and G. longicalyx will be utilized along with one commercial cultivar to determine the influence of seed treatment nematicide on soil nematode level. Lots of each seed source were sent to various institutions for specific nematicide seed treatment application. Two locations have been planted for 2012 with the first set of soil samples collected.