Contrôle genético dos "frutos chochos" no Café "Mundo Novo" Manofactorial inheritance of "empty-locule" in the Mundo Novo coffee

1. Decorre do presente trabalho que no Café Mundo Novo há dois grupos distintos de plantas : a) de baixa ocorrência de frutos chochos; b) de alta ocorrência de frutos chochos. 2. Há evidências de que a existência de 2 grupos distintos de plantas é devida a um par de fatores genéticos Dd. As plantas onde é baixa a ocorrência de frutos chochos são de constituição genética DD. As demais são Dd. Não há o grupo dd, pois que a combinação endosperma ddd e embrião dd é letal. 3. Segundo a hipótese, a letalidade dos fatores dd se manifesta quando o endosperma tem 2 a 3 mm de diâmetro; nesse ponto estaciona o crescimento e êle se transforma num disco (donde o símbolo d para o gen em questão). Raras vêzes a ação letal se manifesta antes dêsse estado e então nada ou quase nada resta do endosperma. Outras vezes a ação letal é tardia: o endosperma se desenvolve em semente mas esta não germina. 4. As populações de café Mundo Novo que estão se formando no Estado de São Paulo terão diferentes proporções de plantas com e sem o defeito das lojas vazias, dependendo isso da fonte onde se procurarem as sementes. 5. Limitando-se a selecionar as plantas Mundo Novo dentro do grupo de baixa ocorrência de chochos o melhorista encontra base científica para ehminar um notório defeito da variedade.<br>It was shown in a recent paper that the occurrence of empty locules in coffee fruits of the variety Mundo Novo (Coffea arabica L.) is due to an arrest in the endosperm development that takes place at a definite stage, leading to the formation of a small disc ; this rudimentary type of endosperm has been called "discoid endosperm". A suggestion was then made that this process might be controlled by genetic factors. Under this assumption, normal plants were DD; plants in which the defect occurred, Dd, and the homozygous, recessive form was lethal. The high correlation between discoid endosperm and empty locules permitted a clear-cut separation of Mundo Novo coffee populations into two classes : a) plants in which the discoid endosperm is not formed (normal plants) ; and b) plants in which the disc occurs (hight percentage of empty locules). A survey was made of three Mundo Novo plantings representing different generations of an once-existing small group of plants. Under the assumption that the original plants (maximum of eight plants) were Dd (F1), the first plantings made with their seeds represented F2 populations and should have DD and Dd individuals in a ratio of 1:2. A second planting has been made with seed collected from 400 plants that represented another group of the supposed F2 generation; assuming that this F2 had 1DD:2Dd, and that 10% of cross pollination occurred, this F3 population should consist of DD and Dd individuals in the ratio of 59:41. A third group of plants that was examined had been planted with seed collected from 15 plants selected from the first planting of the F2 generation. Sampling of these 15 parent plants indicated that according to the presence of discoid endosperm they were 4DD:11Dd; assuming that 10% of cross pollination occurred and taking into account that an equal number (20) of seedlings was selected from each progeny, it was expected that the ratio in this F3 lot would be 51:49. Samples of 100,100, and 262 plants that were examined in the one lot that represented an F2 generation and in the two others that represented F3 generations, respectively, confirmed the above-mentioned expectations. Individual study of the plants belonging to the 15 progenies showed that the 197 plants derived from the 11 Dd plants were in the ratio of 1DD:2Dd; among the 65 plants derived from the 4 DD individuals, only four were Dd, which corresponds closely to a possible 10% of cross pollination. Emasculated flowers of Dd plants that were pollinated with DD pollen produced only normal seeds, thus confirming the genetic origin of empty locules. The frequency of empty locules only seldom reaches the expected 25%. To explain this slight discrepancy, the suggestion is made that some ddd endosperm may attain normal size and shape, although their embryos may not be viable since no dd plants has ever been found. Data on germination obtained in 1950 and 1951 have indicated that apparently normal seed from plants that had a high percentage of empty locules (probably Dd) gave a lower germination than those from plants with a low percentage of empty locules (probably DD)

Avaliação das cultivares Mundo Novo, Bourbon Amarelo e Bourbon Vermelho de Coffea arabica L. em Campinas, SP Evaluation of the cultivars Mundo Novo, Bourbon Amarelo and Bourbon Vermelho of Coffea arabica L., in Campinas, state of São Paulo, Brazil

Com o objetivo de ampliar a diversidade genética da cultivar Mundo Novo, progênies S1 de 92 novas plantas matrizes, selecionadas em 1952, no município de Urupês (SP), foram estudadas em experimento instalado no Centro Experimental do Instituto Agronômico, em Campinas, utilizando-se como testemunhas 12 progênies S2 de Mundo Novo, seis de Bourbon Amarelo e sete de Bourbon Vermelho. O experimento foi delineado em blocos ao acaso com 21 repetições, parcelas de uma única cova e uma planta por cova, tendo sido realizadas colheitas consecutivas durante 33 anos. Foram mensuradas também as seguintes variáveis: índice de avaliação visual, precocidade de maturação dos frutos, porcentagem de sementes dos tipos chato, moca e concha e tamanho das sementes mediante determinação da peneira média. Diferenças significativas foram verificadas na produção dentro e entre grupos de Mundo Novo S1, Mundo Novo S2, Bourbon Amarelo e Bourbon Vermelho, sendo a média de produção das progênies S1, 6% superior à do grupo Mundo Novo S2. Foram observadas nas progênies de Mundo Novo S1 e S2, respectivamente, produtividade 39% e 30% superior à do Bourbon Amarelo e 112% e 99%, respectivamente, à do Bourbon Vermelho. Entre as 30 progênies mais produtivas, 4 pertencem à geração S2 e as restantes à geração S1 de Mundo Novo, indicando a eficiência da primeira seleção realizada em 1943. De modo geral, verificaram-se nas melhores progênies da cultivar Mundo Novo maturação média, sendo CP447, a mais precoce e CP502, a mais tardia. Apenas a progênie CP474 conseguiu peneira média superior às demais. Com o presente trabalho, concluiu-se que as progênies da cultivar Mundo Novo têm ótima capacidade produtiva, boa longevidade e excelente rusticidade. As novas seleções evidenciaram ainda mais o valor dessa cultivar, sendo uma das mais produtivas que se conhece em C. arabica.<br>Coffea arabica L. cv. Mundo Novo is the most outstanding coffee cultivars studied at the Instituto Agronômico, Campinas, State of São Paulo. Besides its rusticity, this cultivar has showed high yield capacity in all Brazilian coffee growing areas. In order to further diversify the Mundo Novo genetic background, new selection of mother trees was undertaken, in 1952, in six sites where former selections were made in Urupês, SP. Four groups of coffee progenies were planted to be compared at the Central Experimental Station, in Campinas, SP: 92 new selections (S1), 12 progenies of selected Mundo Novo (S2), 6 selected progenies of Bourbon Amarelo and 7 progenies of Bourbon Vermelho cultivars of C. arabica. The 117 progenies were planted in a randomized block design, with one-plant plots and 21 replications. Yield data were collected from individual plants during 33 consecutive annual harvests, from 1955 to 1987. Prior to the 1985 harvest, observations were made on the shape of plants, vegetative vigor (IAV index, 1 to 10 points varying from the worst to the best, respectively), fruit ripening (1 point for early, 3 for medium and 5 for late ripening, respectively), seed characteristics, such as flat beans, peaberry and elephant beans, and seed size. Significative differences were found in the yield inside and between progenies groups - Mundo Novo S1, Mundo Novo S2, Bourbon Amarelo and Bourbon Vermelho. The average yield of Mundo Novo S1 was 6% superior to the of Mundo Novo S2, and both groups of Mundo Novo S1 and S2 were more productive than Bourbon Amarelo (39 and 30%) and the progenies of Bourbon Vermelho (112 and 99%), respectively. Among the 30 highest Mundo Novo yield progenies, 4 belong to S2 and 26 to S1, Mundo Novo progenies, indicating the efficiency of the selection of S1 progenies. The highest yield Mundo Novo progenies have medium maturation. However individual plants in the progenies were classified as early, medium or late maturing plants. The Mundo Novo progeny CP447 gave larger number of plants with early fruit ripening and CP502 gave the highest number of late plants. All the best Mundo Novo progenies presented normal flat, peaberry and elephant beans seed percentages and seed size. The progeny CP474 gave several plants with larger seeds. The highest yield S2 Mundo Novo progenies such as P388-17, MP376-4 and the S1 CP502, CP515, CP474, CP447, CP501, CP543, CP475, CP464 and CP441 have already been multiplied in seed plots and are being extensively planted in all coffee regions of Brazil