A Simulated Selection Experiment in Sugarcane1

Abstract

Two objectives of the experiment were: 1) to estimate the probability that the best clones in the test would be retained in selection at various intensities for stalk diameter, stalk length, stalk number per plant, and Brix in single‐stool sugarcane (Saccharum L.) cultivar tests; and 2) to see if subpopulations obtained by selection were superior to the unselected population. Twenty randomly selected sugarcane seedlings from the Florida cultivar development program were clonally propagated by single‐bud cuttings and transplanted to an 18‐block field test with a single plant of each clone per block. The following were later determined for each plant: stalk diameter, stalk length, stalk number per plant, and Brix. Within each block, the 20 plants were ranked for each of the four traits. The ranks were than used to simulate selection within each block at the 5, 10, 15, … 100% levels for each trait. In addition, means for each clone over all blocks were obtained and ranked. In selection at the 5% level (selection of the one best plant per block) the plant of the clone with the best overall mean was retained in 50%, 31%, 28%, and 36% of the blocks for stalk number, Brix, stalk length, and stalk diameter, respectively. For each trait, stringent selection yielded subpopulations averaging better than the unselected population. As we would expect because of environmental variation, some clones that averaged good over all blocks did poorly in one or more individual blocks. It was less common for clones with poor averages over all blocks to excel in an individual block. It was concluded that the population improvement possible with single‐plant sugarcane selection warrants increased use of single‐plant tests.