Cotton

What final live plant population should I target?

In Mississippi, cotton plant populations can vary from 30,000 to 55,000 plants per acre without seriously affecting yields, but 40,000 to 50,000 plants per acre is a good final target. This translates to a desired final population of 3 to 3.5 plants per row foot in 38-inch rows. Growers should avoid high plant populations because they can, 1) shorten the boll loading period, 2) decrease drought tolerance, 3) increase fruit shedding, and 4) increase number of small bolls. Extremely low populations should also be avoided because they can, 1) encourage vegetative development and large plant size, 2) delay reproductive development, 3) shift more bolls to outer fruiting branch positions and to vegetative branches, and 4) increase boll size and micronaire in key fruiting positions.

Seeding rate should be based on number of seed per row foot, rather than pounds of seed per acre. For example, if planting conditions are good and the desired population is 45,000 plants per acre, then the standard germination percentage should be a good predictor of emergence. If the standard germination is 80 %, then 45,000 divided by 0.80 equals 56,250. This means that 56,250 seeds should be planted per acre (same as 4 seeds per row foot in 38-inch rows) to attain a final stand close to 45,000 plants per acre (3.3 plants per row foot in 38-inch rows). Consider the scenario that the weather unexpectedly turns cool. Then, you expect field emergence to be close to the cool germination percentage (60 % in this case). For example, you would expect a final stand of about 33,750 [56,250 x 0.6] (2.5 plants per row foot in 38-inch rows), which is still within the acceptable range.