Cool-season perennial grass growth is suppressed during hot, dry summers. This "summer slump" reduces the availability of grazable forage. Tall-growing perennial warm-season grasses that produce 65 to 75% of their yield in midsummer may provide needed herbage during this period of reduced cool-season forage production. However, establishment of perennial warm-season species is slow and inconsistent when compared to cool-season species. Before these warm-season species can be relied on for summer forage production, a successful establishment methodology must be developed. A study was conducted to evaluate the influence of atrazine [2-chloro·4(ethylarnino)-s-triazine] and carbofuran on establishment of switchgrass (Panicum virgatum L.) and Caucasian bluestem [Boyhtiochloa caucasica (Trin.) C. E. Hubbard]. Treatments of carbofuran at 0 and 1.1 atrazine/ha placed in the row with the seed and of atrazine broadcast at 0, 1.1, and 2.2 kg/ha were imposed in all possible combinations. Another study investigated the influence of limestone, P, and carbofuran on the establishment of switchgrass. Treatments included carbofuran at 0 and 1.1 kg/ha, limestone at 0 and 4.48 Mg/ha, and P at 0 and 22 kg/ha in all possible combinations. Seedling growth rate, leaf appearance rate, plant height, and leaf elongation rate (LER) of seedlings were recorded. Seedling weight and populations were determined at the sixth leaf stage of development. Yields of forage and botanical compositions were also measured in the establishment year. Establishment was further evaluated with yield measurements the year after seeding. Carbofuran application increased first year yield, seedling weight, population, leaf appearance rate, and seedling growth rate. Atrazine reduced seedling population, weight, leaf appearance rate, LER, and yield. Carbofuran partially moderated atrazine influence. The 2.2 kg rate of atrazine tended to injure the switchgrass more than the Caucasian bluestem. In the study investigating limestone and P, carbofuran increased yield, seedling weight, seedling population, LER, seedling growth rate, and leaf appearance rate. The greatest yield, leaf appearance rate, and LER occurred with applications ofP and carbofuran. Even though initial soil pH was 5.1, limestone broadcast prior to planting did not influence seedling measurements and yields in either year. These plantings were made during 1985 and 1986, which were the driest summers in recent years. In spite of the moisture stress, acceptable stands of perennial warm·season grasses were established in both experiments in both years. Including 1.1 kg granular carbofuran/ha in the row, and broadcast application of 1.1 kg atrazine/ha at planting will improve establishment of perennial warm·season grasses. Where the P levels in the soil are low, a broadcast application of 22 kg P/ha improves chances for successful establishment. / Ph. D.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/53580 |
| Date | January 1988 |
| Creators | McKenna, James R. |
| Contributors | Agronomy, Wolf, Dale D., Alley, Marcus, Hagood, B. Scott, Parrish, David, White, Harlan E. |
| Publisher | Virginia Polytechnic Institute and State University |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation, Text |
| Format | xi, 81 leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 18354412 |
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