Melhoramento do cafeeiro: V - Melhoramento por hibridação

Abstract

A hibridação como método de melhoramento do cafeeiro, oferece amplas possibilidades que ainda se acham pouco exploradas. Para o caso da espécie C. arabica, a hibridação entre suas variedades, além de fornecer dados seguros sôbre a constituição genética, permite também a verificação de ocorrência da heterose, o melhoramento sem mudança dos caracteres das variedades, ou sintetização de estruturas genéticas novas. Os cruzamentos interespecíficos poderão contribuir decisivamente para a solução do problema da melhoria da qualidade do produto e dar indicações a respeito das relações das várias espécies e da reação dos fatôres genéticos de uma espécie em ambientes genéticos diversos. Cêrca de 2500 híbridos se acham em estudo na Secção de Genética, envolvendo plantas da mesma variedade, plantas de variedades diferentes e cafeeiros pertencentes a espécies distintas. As diversas possibilidades dêsses cruzamentos no melhoramento do cafeeiro são indicadas, chamando-se especial atenção para os híbridos interespecíficos, principalmente aquêles que envolvem a espécie tetraplóide C. arabica e outras espécies diplóides, como C. canephora, C. Dewevrei e C. congensis. Êstes híbridos triplóides, após duplicação do número de cromosômios, poderão constituir fonte de novas formas de Coffea, permitindo a expansão do cultivo do café era São Paulo.<br>Artificial hybridization in coffee breeding offers possibilities that are still unexplored. Inter-varietal hybridization has been used in Coffea arabica in order to get information about the genetic constitution of the varieties, and occurrence of heterosis, to breed without changing the morphological characters of the varieties and also to synthesize new genetic types of economic value. Inter-specific hybridization has been employed for improvement of cup quality and to furnish data about the relationship of various coffee species and the behaviour of known genetic factors of one species in the genetic background of other coffee species. About 2500 inter-varietal and inter-specific artificial hybridization have been made in Campinas during the last 20 years. The economic value of some of these hybrids has been stressed in this paper and special attention has been called to the inter-specific hybrids involving the tetraploid C. arabica and other known diploid species as C. canephora, C. Dewevrei and C. congensis. After chromosome doubling of these triploid hybrids, the resulting allopolyploids may be of economic value

Genetic diversity among coffee tree progenies Big Coffee VL based on growth traits and production

“…However, broadening of the genetic variability of C. arabica can be achieved through mutations (Krug, 1949), introductions (Sakiyama et al, 2005), and hybridizations (Krug and Carvalho, 1952), thereby, increasing the gains from plant breeding programs for the release of new cultivars.…”

Estimation of Leaf Area by Linear Dimensions in Coffea dewevrei

“…Other species such as Coffea liberica, Coffea racemosa, Coffea dewevrei, Coffea eugenoides, Coffea congensis, Coffea stenophylla, are of fundamental relevance in breeding programs [1]. In this context, the Coffea dewevrei species has important attributes, such as resistance to rust (Hemileia vastatrix), to some nematodes [3], and to Leucoptera coffeella [4], considered as one of the main phytosanitary problems of coffee [5], in addition to dry tolerance [6].…”

“…Coffee Coffea dewevrei, also known as Excelsa coffee, is self-incompatible [7] and highly productive [6]. The plants can reach eight to ten meters in height, and their leaves are large, measuring about 26 cm long and 13 cm wide, and coriaceous [8].…”

“…Representation of the length (L) along the midrib and the maximum width (W) of leaves Representation of the LISchmildt et al; IJPSS, 28(6):[1][2][3][4][5][6][7][8] 2019; Article no.3The leaves were harvested from six year old plants. A total of 140 leaves of different growth collected, obeying the four cardinal points (north, south, east and west) distributed in the lower, middle and upper third of The length (L, in cm), along the central midrib and greater width (W, in cm) of the leaf blade sured from all leaves(Fig.…”

Cytology of a Spontaneous TriploidCoffea CanephoraPierre ex Froehner

“…Triploid forms in the genus Colfea have been reported to arise as a result of crosses between tetraploid and diploid species (CRAMER 1957;KRuG and CARVALHO 1952;MENDES 1947;MEDINA 1963;SYBENGA 1960;ANo-NYMOUS 1957). Artificial production of such hybrids is always aimed at combining economic characters found in different species.…”