1998 Cotton VarietiesThis publication presents information on the performance of commonly available cotton varieties and several varieties not available in the marketplace. The data were gathered from numerous tests conducted at various locations in 1997 and, in some cases, reflect averages over two or three years. Sixty varieties were evaluated in the Delta and in the Hills in 1997. SelectionConsider several factors when selecting a variety to plant. Ability to yield is perhaps the major consideration; however, you should also consider maturity, plant size, transgenes, and fiber properties. As with many other crops, it is a good idea to plant more than one variety. This can distribute the picking season and reduce the elapsed time from open bolls to picking. Another important reason to plant more than one variety is that you can evaluate the performance of different varieties on your farm. PropertiesVarieties are continuing to improve in yield and time of maturity. At the Stoneville location, the number of days from planting to harvest has declined at the average rate of 1.18 days per year over the past 30 years. This is a direct result of breeding and changes in management. When comparing varieties in this publication, remember these tests are conducted under controlled conditions, in small plots, on uniform soils, and replicated several times to reduce variation other than variation between varieties themselves. Results of the test for yield differences are statistically analyzed to determine if differences are real or only the result of chance. Listed are explanations of some terms to help you use this information. Lint percent is a ratio of seed to lint and not a measure of gin turnout. Gin turnout usually will be several percentage points below this value and will take into account trash, moisture, and other factors. This value is derived using a hand-picked sample. Seed Index is the weight in grams of 100 fuzzy seeds from a particular variety. Seed index can be useful in comparing seed size of varieties; that is, the higher the seed index the larger the seed size and the fewer number of seeds per pound. You can calculate the approximate number of seeds per pound for a variety by using the seed index value: 454 ÷ seed index x 100 = number of fuzzy seeds/lb number of fuzzy seeds/lb + 700 = approximate number of acid-delinted seeds/lb Boll size is the average weight in grams of the lint and seed (seed cotton) contained in a boll for a particular variety in this test. Length value represents the length in inches of the upper-half mean or 50 percent span. Uniformity is calculated by dividing the 50 percent open length by the 2.5 percent span length and multiplying by 100. The higher the uniformity ratio, the more desirable. Strength. The value reported in this publication is an H.V.I. reading and is reported in grams per tex. Elongation is a measure of elasticity, or how far fibers will stretch before breaking. The higher the elasticity, the more desirable. Micronaire is a measure of fineness of individual fibers and can indicate fiber maturity. Micronaire may be influenced by weather, variety, and management. LSD (--). Numbers within a particular column must differ by this value in order for them to be considered significantly different at that particular level of probability. MaturityThe variety trials are divided into two maturity categories, early and mid. Industry representatives specify into which test their entries are placed. Fiber QualityMany factors affect cotton quality. These factors include cultural practices, weather conditions during the growing and harvesting seasons, crop preparation for harvest, and genetic characteristics of varieties. Any factor that causes stress during boll filling and development can cause reductions in quality of fiber characteristics that will be reflected in grade value. All varieties differ, and often these differences offset one another. It is hard to predict how a selected variety will perform on a particular farm until it is actually planted and grown there. It should be noted that most of the varieties tested greatly outperformed Mississippi's average for most years. This indicates that most of these varieties have the genetic potential to be good performers under the right soil conditions, favorable weather conditions, and proper management routines. Varieties For Narrow RowsFor the purpose of this publication, narrow row refers to a row spacing less than 36 inches. Some data presented in this publication were collected at Choctaw from rows spaced 30 inches apart. At this time, there are not enough data to indicate that any particular variety is superior to all others when grown in narrow rows (30-inch spacing). Research indicates that narrow-row cotton, when properly managed, will yield as well or slightly higher than conventional row spacing. It stands to reason that the faster fruiting, early type varieties would be superior to the longer season varieties. Management, of course, is the deciding factor. If you are planting in narrow rows, base your variety selection on your experience with particular varieties and your management. Plant proven varieties on the bulk of your acreage, and try some others with high yield potential. Do not mix early varieties and late varieties in the same field. When planting different varieties, plant enough of each one to be managed as it should. If you are switching to narrow rows, a good recommendation is to plant the bulk of your acreage in the variety that has worked best for you on your soil type. Ultra Narrow RowUltra Narrow Row cotton describes broadcast cotton or cotton planted in rows spaced 7 to 10 inches apart. Highly modified planters or grain drills are used to plant ultra narrow cotton. Ultra narrow row cotton is harvested with a finger stripper rather than with a conventional spindle picker. In 1997 no official state variety trials were conducted in ultra narrow rows. Currently no data indicate that any particular variety is superior to all others when grown in ultra narrow rows. Based on farmer experience, if you wish to plant ultra narrow row cotton, plant the bulk of your acreage in the leading variety for your area. Plant populations for ultra narrow rows will be in the 100,000-120,000 plants per acre range. At these populations, the plant will respond to its surrounding and alter its morphology to conform to its environment. NematodesRecent research indicates that nematodes may be reducing cotton yields more than previously thought. Before making drastic changes in your production practices, have your soil sampled for infestations of this pest. When nematodes are present at levels above threshold levels, implement control strategies. Control strategies may vary from crop rotation, especially a 1- or 2-year corn rotation for reniform nematodes, to chemical treatments. Before making nematode-control decisions, get advice from your county Extension agent. No varieties are considered completely resistant to commonly occurring species of nematodes. Transgenic CottonIndustry first entered a transgenic cotton variety in the variety trials in 1996; numerous transgenic varieties were tested in 1997. The transgenic varieties were treated like conventional varieties, including chemical control of tobacco budworm. BXN varieties were not treated with Buctril, and Roundup Ready varieties were not treated with Roundup Ultra. The purpose of the test was to evaluate the ability of the transgenic line to yield and perform, not to evaluate any value-added trait that may be associated with the variety. Table 1. Lint yield of entries in the 1997 Early Maturing Cotton Variety Test at various Delta locations
Bold type indicates entries are not different from the top-yielding entry in each column at p<0.1. Table 2. Lint yield of entries in the 1997 Midseason Cotton Variety Test at various Delta locations
Bold type indicates entries that are not different from the top-yielding entry in each column at p<0.1. Table 3. Lint yield of entries in the 1997 Early Maturing Cotton Variety Test at various locations in the Hills of Mississippi.
Bold type indicates entries that are not different from the top-yielding entry in each column at p<0.1. Table 4. Lint yield of entries in the 1997 Midseason Cotton Variety Test at various locations in the Hills of Mississippi
Bold type indicates entries that are not different from the top-yielding entry in each column at p<0.1 Table 5. Lint yield of entries in the Early Maturing Cotton Variety Test at various Delta locations in 1996-97.
Table 6. Lint yield of entries in the Early Maturing Cotton Variety Test at various Delta locations in 1995-1997
Table 7. Lint yield of entries in the Midseason Cotton Variety Test at various Delta locations in 1996-97
Table 8. Fiber properties of Early Maturing Varieties, averaged across five Delta locations
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