Bragantia
URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/9887
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Item Genética de Coffea. IX - Observações preliminares sôbre quimeras genéticas em Coffea arabica L.(Instituto Agronômico (IAC), 1946-06) Carvalho, A.; Krug, C. A.Após uma discussão geral sôbre a natureza das quimeras vegetais, esclareceu-se a ação dos alelos Na na em Coffea arabica L., chamando a atenção para diversos casos de mutações somáticas ocorridas com êstes fatôres, o que demonstra a sua instabilidade em determinados ambientes genéticos. A seguir, apresentam-se os resultados de diversas análises, com o fim de esclarecer a natureza genética de quatro dessas mutações somáticas. No primeiro caso (planta 605), o ramo murta (Na na) produzido numa planta nana (na na) revelou ser inteiramente da constituição Na na ou possuir, pelo menos, duas camadas de células geradoras mutadas, entre as quais a segunda, responsável pela origem dos gâmetas. Em duas outras plantas examinadas (RP 101-91 e RP 103-17), de constituição Na na (murta) e que produziram ramos com folhagem típica de bourbon (Na Na) a mutação, entretanto, não atingiu a segunda camada geradora, constituindo os ramos mutados prováveis quimeras genéticas periclinais. Não se conhece a estrutura exata dessas quimeras, porquanto não se sabe ainda quantas camadas geradoras existem em Coffea arabica L., e qual ou quais delas influenciam a forma das fôlhas. Apenas se conclui que a segunda camada geradora, aparentemente, não é a principal responsável por êsse caraterístico.Item Agentes de polinização da flor do cafeeiro (Coffea arabica L.)(Instituto Agronômico (IAC), 1949) Carvalho, A.; Krug, C. A.This paper describes the methods used and presents an analysis of the results obtained from three years of study, to determine the separate and inter-related effects of various agents such as gravity, wind and insects, in the pollination of flowers of Coffea arabica L. Observations were made and data obtained from several thousands of normal and castrated flowers that were maintained under natural and controlled conditions. It has been found that the importance of gravity, wind, and insects in pollination of the flowers may vary appreciably in relation to local environmental influences. The data obtained, however, indicate certain trends that are of definitive interest. Based on the total number of ovules, it was found that in 1228 normal flowers observed, 62 percent produced seed. This value is believed to represent in general the percentage of fertilization that might be expected to occur naturally. In tests designed to exclude the influence of wind, insects, and gravity, it was found that an average of 24 percent fertilization (within flowers) occurred. In measuring the effects of the combined agents of wind, insects and gravity it was found that 18.5 — 32.7 percent fertilization occurred as a result of self-pollination and 4.1 to 5.2 percent was due to cross-pollination. Analysis of the data also show in all except one case, the percentage of fertilization resulting from self-pollination was higher than that from cross-pollination. These findings show the importance of self-pollination in Coffea arabica. The use of castrated flowers was particulary helpful in determining the maximum effect of each of the pollinating agents studied under isolated controlled conditions. The general analysis of all data indicates that in the case of self-pollinated normal flowers the influence of wind and insects are about equal and that the effect of gravity is relatively less and likely to be of variable importance. In the case of factors affecting cross-pollination of normal flowers, wind seemed to have the most important influence. Based on a study of several different samples with large numbers of seed harvested from normal flowers, it. was also found that the percentage of seed resulting from cross-pollination was 7.3 — 9.0%. This percentage range of 7.3 — 9.0 is comparable to that of 4.1 — 5.2 shown above, the latter percentage range being based on total ovules and the former on the total seed harvested. Again these data emphasize the relatively limited occurence of cross-pollination in C. arabica.Item Melhoramento de Coffea arábica L. var Bourbon. estudo das produções individuais de 1107 cafeeiros no período 1933 a 1939 e resultados parciais de algumas de suas progênies(Instituto Agronômico (IAC), 1941) Mendes, J. E. Teixeira; Brieger, F. G.; Krug, C. A.; Carvalho, A.Coffee culture in São Paulo is done by planting 3, 4, 5 or even, more seedlings in each bed (cova). This is very troublesome specially for coffee selection work. Thus, it was found necessary to plant certain area of ground using just a single seedlingin .each bed (cova). 1.107 coffee trees of Coffea arabica var. bourbon were planted in quadrangle, 3 meters apart frcm each other occupying 1 Ha. of.land. (1931, April). 2. Tilling, fertilizing, harvesting were the same for every individual plant. The results of 7 years work, since the first remarkable crop was harvested in 1933, are presented in this paper. Harvest was done twice or three times yearly, when the berries were ripe. 3. Average production totaled 6 5 . 7 0 arrobas (each arroba equals. 15 Kgrs.) of clean coffee per hectare of land. 4. The data obtained showed enormous variability in the coffee plants. Several individuals were very poor yielders, others suffered die- b a c k in consequence of over production and still others producing hea- vily in one year dropped it in the next, but by putting. forth new shoots and new leaves reacted well so that a good crop was obtained again in the following year. Finally some bore fruit during the whole span of the experiment and did not show great variation in production from one year to the next. 5. The Departament of Genetics of the Instituto Agronômico making use of the data obtained marked several individuals for progeny tests.Item Genética de Coffea . XII — Hereditariedade da côr amarela da semente(Instituto Agronômico (IAC), 1949) Carvalho, A.; Krug, C. A.The known species of Coffea can be grouped into two categories according to the color of their endosperm which is either green or yellow. The commercially cultivated varieties of Coffea arabica L. and Coffea canephora Pierre ex Froehner are well known for the green color of their seed while the less known varieties of Coffea liberica Hiern and Coffea Dewevrei De Wild, et Th. Dur. have yellow Feed. In 1935, however, a yellow seeded type of C. arabica, was found in Brazil and has been described as Coffea arabica L. var. cera K.M.C. ; it is believed to have originated by mutation from Coffea arabica L. var. typica Cramer. In this paper the authors present the results of a genetic study of the yellow seeded mutant known as "cera". It has been found that in C. arabica, yellow endosperm is controlled by one pair of recessive factors cece. Hybrid seeds containing a Cece embryo were green (xenia), their endosperm being either Cecece or CeCece. Cera is a tetraploid variety and when it was crossed with diploid Coffea species having yellow endosperm, it was found to produce only yellow hybrid seeds. The cera, which is a yellow seeded mutant has been useful not only for definitely showing that the bulk of the coffee seed is true endosperm, but it has also proved useful is study of the biology of the coffee flower.Item Taxonomia de Coffea arabica L. II - Coffea Arabica L. Var. Caturra e sua forma Xanthocarpa(Instituto Agronômico (IAC), 1949-09) Krug, C. A.; Mendes, J. E. T.; Carvalho, A.Uma nova variedade de Coffea arabica L., provavelmente originária de Manhumirim, Estado de Minas Gerais, e cultivada em pequena escala no Estado do Espírito Santo, foi recebida, pelo Instituto Agronômico de Campinas, em 1937. Trata-se da variedade caturra. Carateriza-se por apresentar porte menor do que o da variedade bourbon, da qual provàvelmente se originou. Os internódios são bem curtos, tanto no caule como nos ramos, sendo intensa a ramificação secundária e de ordem inferior. As fôlhas são de um verde bem escuro, maiores e proporcionalmente mais largas do que as do Bourbon. As flores são pouco menores e os frutos e sementes um pouco maiores do que as dessa variedade. No presente trabalho apresentam-se os resultados das pesquisas taxonômicas relativas a essa nova variedade de C. arabica e alguns dados preliminares referentes à sua constituição cromosômica e genética. Verificou-se ser de 2n = 44 o número de cromosômios somáticos e, dos cruzamentos com as variedades typica e bourbon, conclui-se que os seus principais caracteres são devidos à ação de um só par de fatôres genéticos dominantes principais (Ct Ct). As observações preliminares relativas à produtividade indicam que se trata de uma variedade de elevada capacidade produtiva, merecendo, por conseguinte, a atenção que se vem dando aos trabalhos ora em realização nas principais zonas cafeeiras. A forma xanthocarpa parece diferir do Caturra Vermelho apenas na coloração amarela dos frutos, que é devida ao mesmo fator (xc xc) que carateriza a forma xanthocarpa da variedade typica (2).