Abstract
Twelve high-yielding soybean cultivars of Maturity Groups 000-IX were planted in Puerto Rico at two locations during two years in bimonthly plantings, beginning January of each year. Three replications were used at each planting. Cultivars were assigned to four Maturity Classes (MC), defined on the basis of average number of days needed to reach stage RS (full maturity) in tropical environments. Flowering and maturity dates, plant height at maturity, seed yield, and protein and oil percentages were recorded. MC and planting month had significant effects on days to maturity and seed yield. MC was also significant for protein percentage, and planting month for plant height. Cultivars within MC were significantly different for all traits except seed yield. Results indicate that Maturity Groups IV, V and VI would give the greatest total yearly seed yield, also at individual plantings. Seed yield averaged over planting dates was 2119 kg ha-1, with protein and oil contents of 43.6 and 20.1 %, respectively, and an average plant height of 43 cm. Almost four crops per year may be obtained with cultivars of these maturity groups with a yearly seed yield of 8476 kg ha-1, 3696 kg ha-1, of protein and 1704 kg ha-1 of oil. Plantings during March and May had the highest seed yields. In crop rotation sequences, soybeans of all maturity groups would yield their best if planted at this time of year.
