Studies were conducted in the central mountainous region of Puerto Rico to determine the adaptability of 18 pummelo clones. Data on fruit number, weight and yield efficiency were collected during three consecutive crop years beginning the fourth year after planting. Clones Dry Pink, Thong Dee White and African Seedling were the best in terms of total number of fruits produced per tree, Production increased with age from over forty fruits for four-year-old trees to over sixty fruits per tree for six-year-old trees. Fruit weight per tree also increased with age, reaching a maximum of 87 kg of fruit for six-year-old trees. Clones Dry Pink and Thong Dee White were the best in terms of total fruit weight. Yield efficiency measured in terms of number of fruits per cm of stem diameter also increased with age from an average of 5.50 for four-year-old trees to 7.55 for six-year-old trees. Best yield efficiency was obtained with clones Dry Pink, Reinking, Thong Dee White and Green Favorite. These results indicate an excellent adaptability of the pummelo to the soil and climate conditions prevailing in the central mountainous region of Puerto Rico.
Stem cankers and root rot of coffee plants were detected in the nurseries. Proliferation of adventitious roots at the base of the stems was also observed. Several fungi were isolated from the root and stem lesions and pathogenicity trials were conducted under the humid conditions of the shadehouse. Typical disease symptoms were reproduced by Myrothecium roridum and Rhizoctonia solani in the root and in the stem of the inoculated plants.
Applications of gibberellic acid (GA), paclobutrazol and gibberellic acid (Paclo/GA), fluoridone and gibberellic acid (FL/GA), and abscisic acid (ABA) were made to synchronize flowering in coffee trees (Coffea arabica L.). Overall growth of trees and branches was not affected by the treatments. Production of new leaves was not affected by the treatments. However, the Paclo/GA treatment tended to increase the production of secondary branches. Flower bud production was affected by the ABA treatment during the first three weeks, showing an initial reduction in number and a late development of buds. Plants receiving the GA treatment produced more flowers during the first week of evaluation as well as a higher number and greater weight of mature fruits during the first week of harvesting.
Thirteen lines from the coffee germplasm collection of the Adjuntas Agricultural Experiment Substation, lines T-5175 and T-8667 from Costa Rica, and four advanced multilines from the Portugal Research Center for Coffee Rust (CIFC; ‘Centro de Investigación de la Roya del Café de Portugal’) were evaluated for resistance to Hemileia vastatrix and their performance under coffee production conditions in Puerto Rico. The evaluations were conducted in the laboratory and on selected coffee farms. Lines of “Catimor” and “Sarchimor” types were selected based on their reaction to the rust pathogen and excellent agronomic characteristics and named ‘Frontón’ and ‘Limaní’, respectively. Incidence of black beans was examined in red, medium and green beans and was significantly higher in line T-5175, in plantings <300 meters above sea level, and in medium ripe and green fruits. Catimor lines from the CIFC were superior to the check ‘Caturra’ in fruit production and yield of green coffee.
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