Morphology and cytology of coffee
C. liberica has larger flowers and berries and more petals, stamens, and segments, and blossoms earlier than C. robusta and C. excelsa. Double fertilization occurs a day after the flower opens. The embryo sac then increases in volume and presses the inner integument cells. The outer integument cells multiply to form the perisperm. After degeneration of synergids and antipodals, the zygote enters into a resting stage near the micropyle until the endosperm has reached the multinucleate stage. The first division of endosperm occurs within 21 to 27 days after flower opening. As the endosperm enlarges the perisperm is pressed to give room to the new tissue. The fertilized egg begins to divide 60 to 70 days after flower opening and completes development about one and a half months later. A pronounced negative correlation exists between fruit-set and peaberry percentages. C. liberica had the greatest percentage of fruit set and the lowest percentage of fruit set and the lowest percentage of peaberry. Weather conditions during flowering adversely affected the setting of fruit, and climatic factors governing the physiological processes in the coffee plant were one cause of the failure of some fertilized ovaries to develop into mature fruit. Shedding of immature fruits, a natural process to prevent overloading, occurred in two separate periods. During the first period unfertilized or incompletely fertilized ovaries were shed; during the second, half-developed berries were discarded. Three-seeded berries were found in all species but there was not a single empty bean. The three species have the same chromosome number in root-tip cells and microsporocytes. Gametic cells have 22 chromosomes and somatic cells have 44
| Main Authors: | , |
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| Format: | biblioteca |
| Published: |
Jun-
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| Subjects: | COFFEA CANEPHORA, COFFEA EXCELSA, COFFEA LIBERICA, CITOLOGIA, FRUTO, FLORES, POLEN, NUMERO DE CROMOSOMAS, MEIOSIS, |
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