Project Number: 6202-21000-029-02
Project Type: Specific Cooperative Agreement

Start Date: Sep 01, 2007
End Date: Aug 31, 2009

Objective:
The primary objectives of the proposed research are: 1) Develop simple methods of screening pecan rootstock cultivars and selections for salt tolerance. 2) Determine growth rates, and uptake of Na and Cl by the pecan cultivars and selections available at the NCGR-Pecan at Somerville, TX.

Approach:
Short-term Seedling Response Test: This experiment will involve the observation of seedling leaf response when seedlings are subject to irrigation with CaCl2 and Na2SO4 solutions containing nutrients and other minerals. These salts are chosen, because previous experiments indicate that pecan seedlings are sensitive to Na and Cl. Seedlings will be grown in vermiculite, irrigated with a nutrient solution, and the CaCl2 and Na2SO4 salts will be added to the nutrient solution in a step wise manner. Leaf injury and changes in transpiration rates will be monitored for a week to ten days, after the application of the first level of salinity. The concentration of the saline nutrient solutions will be increased to the second level, and the same measurements will commence upon a reduction in transpiration or the appearance of leaf burn. Leaf samples will be collected and analyzed for the major cations and chloride. Six replicated observations will be made per treatment. Long-term Seedling Response Test: This experiment will be conducted in pots similar to the short-term seedling response experiment, except that growth media will change to sandy loam, and the treatments involving CaCl2 and NaSO4 solutions will be fixed at two concentrations from the beginning of the test. Upon the completion of the first year growth, leaf will be stripped and be analyzed for uptake of Na, Ca, K and Cl. Shoot length will also be measured. Greenhouse temperature will be dropped similar to the beginning of March, which allows for root growth but not leaf growth. One set of the pots will be leached with tap water, and another set will continue to be watered with saline solutions. This treatment plan will be maintained for 1 to 1 1/2 months, then the temperature of the greenhouse will be raised, the original saline treatment will be reactivated. Leaf and shoot growth will be determined in 1 or 1 1/2 months. Leaf and root samples will be analyzed for Na, Cl, and Ca. This experiment will be conducted in six replicates.