Pachyrrhizus tuberosus, popularly known as yam bean, ("feijão-macuco" or "jacatupé" in portuguese) is one of the tropical food plant species bearing edible tuberous roots. The purpose of this study was to evaluate the plant's growth, correlating the development of the plant parts in the vegetative, flowering, fruiting and tuberous root formation stages, as well as assessing the importance of staking the plants and pruning the inflorescence in the development of the plant and in the yield of tuberous roots. The study was carried out in a Rio Solimões' floodplain area from August 1993 to May 1994, with 1,925 mm of rainfall, 26ºC average temperature and 86.5% relative humidity. The behavior of three genotypes, identified as 1, 2 and 3, which were submitted to four kinds of plant management: with and without staking the plants and with and without pruning the inflorescences. The experimental design was completely randomized blocks in a factorial scheme of 3 x 2 x 2 (genotypes, staking, and inflorescences pruning, respectively) with three replications. Plots measuring 15.5 x 25.0 m were used. The staking treatment increased the plant and stems dry matter weight. Usually there was a steady increase of the above and below ground parts with staking. Growth rates were similar to all genotypes. Staked plants showed a tendency to higher relative growth. The pruning of the inflorescences promoted up to 4.6 fold increase in the tuberous roots weight. In addition to raising the leaves dry matter weight, inflorescence pruning also furthered an increase in the a, b and total chlorophyl grades 160 days after sowing. According to results obtained, it was concluded that staking plants associated with the pruning of the inflorescences improved the development of the "feijão-macuco".
Pachyrrhizus tuberosus; staking; inflorescence pruning; tuberous root formation; chlorophyl
