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Selection of adapted forms of Theobroma cacao L. with K.A.T.R.I.N./Tanzania

by Muttscheller, R.W. von.
Publisher: Abr 1972Subject(s): THEOBROMA CACAO | PLANTULAS | RESISTENCIA A LA SEQUIA | SOMBRA | VIGOR HIBRIDO | ADAPTACION | TANZANIA | THEOBROMA CACAO | SEEDLINGS | DROUGHT RESISTANCE | SHADE | HETEROSIS | ADAPTATION | TANZANIA | THEOBROMA CACAO | PLANTULE | RESISTANCE A LA SECHERESSE | OMBRE | VIGUEUR HYBRIDE | ADAPTATION | TANZANIE In: Tropenlandwirt (Alemania, R.F.) v. 73 p. 31-58Summary: The first cocoa was introduced into Tanzania 70 years ago despite the fact that a pronounced dry season occurs there. It can be presumed that nature itself has done some selection on drought resistance during this period of seven decades. About 17 years ago a Dutch plantation company resumed cocoa cultivation in the country. It was found, however, that the imported types could have more drought resistance. Due to that fact a trial was laid out to examine the local population of cocoa trees. As preliminary studies climatical records were compared with those of other older cocoa growing regions. Climate and soil conditions of a cocoa growing area in the Congo (1), which are similar, were the basis of the trial. For the trial 24 phaenotypically different types of cocoa were selected. As a means of description for size, formation and colour of the pod as well as for size of bean and colour of cotyledons a recording form was established. The seedlings were planted with three replications under four different treatments in randomized blocks on a slope facing North and with an inclination of 12 percent: uphill without shade; uphill with shade; downhill without shade; downhill with shade. As criteria for vigour of growth, early maturity and drounght resistance at four weekly intervals over a period of three years the following stages of development were recorded: formation of the fan; formation of the first flowers; first setting of fruit; measuring of stem diameter and stem volume. After three years the mean values of stem diameter and stem volume were compared statistically. The seedlings were planted at the end of the rainy season and were not mulched in order to put them under stress conditions from the very beginning. The losses were high occordingly; the average was 35 percent but not enough to discontinue the trial. Due to detailed recording the types No. 13, 14, 16 and 18 were isolated as outstanding, and they can be called adapted forms. As it was mentioned in the discussion, the trial was only meant to find adapted forms which were suitable to serve as root stocks for the budgrafting of flavour cocoas under the climatic conditions described. Also a scheme was developed to achieve results in the shortest possible period of time.
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The first cocoa was introduced into Tanzania 70 years ago despite the fact that a pronounced dry season occurs there. It can be presumed that nature itself has done some selection on drought resistance during this period of seven decades. About 17 years ago a Dutch plantation company resumed cocoa cultivation in the country. It was found, however, that the imported types could have more drought resistance. Due to that fact a trial was laid out to examine the local population of cocoa trees. As preliminary studies climatical records were compared with those of other older cocoa growing regions. Climate and soil conditions of a cocoa growing area in the Congo (1), which are similar, were the basis of the trial. For the trial 24 phaenotypically different types of cocoa were selected. As a means of description for size, formation and colour of the pod as well as for size of bean and colour of cotyledons a recording form was established. The seedlings were planted with three replications under four different treatments in randomized blocks on a slope facing North and with an inclination of 12 percent: uphill without shade; uphill with shade; downhill without shade; downhill with shade. As criteria for vigour of growth, early maturity and drounght resistance at four weekly intervals over a period of three years the following stages of development were recorded: formation of the fan; formation of the first flowers; first setting of fruit; measuring of stem diameter and stem volume. After three years the mean values of stem diameter and stem volume were compared statistically. The seedlings were planted at the end of the rainy season and were not mulched in order to put them under stress conditions from the very beginning. The losses were high occordingly; the average was 35 percent but not enough to discontinue the trial. Due to detailed recording the types No. 13, 14, 16 and 18 were isolated as outstanding, and they can be called adapted forms. As it was mentioned in the discussion, the trial was only meant to find adapted forms which were suitable to serve as root stocks for the budgrafting of flavour cocoas under the climatic conditions described. Also a scheme was developed to achieve results in the shortest possible period of time.

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