No matter what the crop, its yield potential is set before it blooms,” Agronomist Charles Stichler reminded farmers at the Cotton Pre-Planting Seminar held recently in Weslaco, Texas. Crop management, Stichler said, must take place early in the cycle, not just before or after the bloom stage.
“It's like a horse race,” said Stichler. “When that crop blooms, the race is half over.” With cotton, 90 percent of the crop that will be harvested is already on the plant at first bloom. The finishing takes place after the first bloom when yield and quality are brought to fruition. There is a definite sequence of growth in cotton and you can't speed it up: the normal timeframe for Rio Grande Valley cotton is 155 days to 165 days.
Forty days prior to bloom, and 20 days before you can see them, microscopic bracts of the square begin to form. From then on, the number of locks is determined, then the number of seeds that are going to be in the locks. “The more seed you set, the more lint you'll produce.”
On Day 22 the pollen cells begin dividing. It is important that Roundup be applied before this point (on Roundup Ready varieties) or it will kill the pollen cells as they begin to divide and pollination will not take place. Three days before bloom, fibers begin to form on the skin of the seed. Two days prior to bloom, fibers elongate off the seed. If the cotton is stressed when fibers are growing, the result will be a short staple. If there is adequate water, it is pumped into the fiber cells, pushing the fibers to maximum length.
A critical issue, said Stichler, is the size at first bloom of the cotton plant. By counting the number of nodes from the first flower up to the terminal, a producer can determine the yield potential of that plant.
Stichler explained that there is a difference between new cell formation, which is dependent on warm weather, and cell expansion, which is controlled by water.
As all farmers know, nothing happens in plants without water. Water is the circulatory system of plants, just like blood is to humans.
Temperature, another important variable, drives the cell activity. “We want to get our cotton in early, but getting it in too early causes problems.” Cotton is not going to come out of the ground until the temperatures get higher. “So you're wasting energy by planting when the soil temperature is less than 60 to 65 degrees.”
“If you don't set fruit, especially in the early positions, you missed it,” said Stichler. He warned producers against planting too thick, which will delay the onset of the first fruiting branch. He advised thinning plants to three to four plants per foot.
Internode length is a sensitive indicator of the condition of the plant. Stichler advised farmers to take a look at their plants. A short internode length where leaves are thick can be the result of a cold front coming through and the plant didn't expand. Examining internode length can tell a grower whether he needs to apply more or less water.
Soil is competitive with plants for nutrients. In order for a nutrient to be absorbed by a root, it must be dissolved in the water. Putting fertilizer on top of the soil can result in having it washed away with a heavy rain.
Stichler talked about the use of mepiquat chloride, which sets up a plant for higher yield. But it's not a magic bullet, he warned. “If you've got good cotton, it makes it better, but it won't help a poor crop.”