Genetic evaluation and selection of cocoa tree clones / Avaliação genética e seleção de clones de cacaueiro

The cultivation of cocoa is of great socio-economic importance worldwide. Cocoa beans are the essential raw material for chocolate production. The variability of cacao studied presents only a small fraction of the existing genetic diversity, mainly in the Amazon region. Furthermore, just a small part of this variability has been exploited in cocoa breeding. Thus, the present study processed the genetic evaluation and selection of cocoa clones, based on morpho-agronomical traits. For this, we evaluated 145 clones, during 37 harvests from, four consecutive years. The following traits were evaluated: total number of fruits collected (TNFC), total number of healthy fruits (TNHF), weight of wet seeds from healthy fruits (WWSHF), average weight of wet seeds per healthy fruit (AWWSHF), weight of dry seeds from healthy fruit (WDSHF), average weight of dry seeds per healthy fruit (AWDSHF), percentage of fruits with witches' broom disease (PFWB), percentage of fruits with borer (PFBR), percentage of fruits with germinated seeds (PFGS), number of branches with witches' broom disease (NBWB), and number of inflorescence with witches' broom disease (NIWB). Significant differences (P < 0.05) among the clones were observed for all traits, which reveal an expressive variability and possibility of gains with selection. The highest significant correlations (P < 0.05) occurred between traits TNFC and TNHF (0.94), TNHF and AWWSHF (0.86), and TNHF and AWDSHF (0.86). Based on the selection index, the clones POUND 12 and CAB 12, 228, 253, 257, 258, and 422 were the most suitable for selection.

O cultivo do cacau tem grande importância socioeconômica mundial. Os amêndoas de cacau são a matéria-prima essencial para a produção de chocolate. A variabilidade do cacaueiro avaliada representa apenas uma pequena fração da diversidade genética existente, principalmente na região amazônica. Além disso, apenas uma pequena parte dessa variabilidade foi explorada no melhoramento de cacau. Dessa forma, o presente estudo teve como objetivo realizar a avaliação genética e seleção de clones de cacau, com base em características morfo-agronômicas. Para isso, foram avaliados 145 clones, durante 37 colheitas, em quatro anos consecutivos. As seguintes características de frutos e sementes foram avaliadas: número total de frutos colhidos (NTFC), número total de frutos sadios (NTFS), peso de sementes úmidas dos frutos sadios (PSUFS), peso médio de sementes úmidas dos frutos sadios (PMSUFS), peso de sementes secas dos frutos sadios (PSSFS), peso médio de sementes secas dos frutos sadios (PMSSFS), porcentagem de frutos com vassoura-de-bruxa (PFVB), porcentagem de frutos com broca (PFBR), porcentagem de frutos com sementes germinadas (PFSG), número de ramos com vassoura-de-bruxa (NRVB) e número de almofadas florais com vassoura-de-bruxa (NAFVB). Diferenças significativas (P < 0,05) entre os clones foram observadas para todas as características, o que revela uma expressiva variabilidade e possibilidade de ganhos com a seleção. As maiores correlações significativas (P < 0,05) ocorreram entre os caracteres NTFC e NTFS (0,94), NTFS e PMSUFS (0,86) e, NTFS e PMSSFS (0,86). Com base no índice de seleção, os clones POUND 12 e CAB 12, 228, 253, 257, 258 e 422 foram considerados os mais adequados para a seleção.

Transpiration of young cocoa trees under soil water restriction

Cocoa plantations in Brazil have been expanding beyond the borders of traditional regions by implementing a strategy based on irrigation and the establishment of crops exposed to full sunlight. The quantification of transpiration is essential to the establishment and management of crops, and is the main factor in the determination of water demand. This study had as its objective the estimating of transpiration of young cocoa trees as a function of reference evapotranspiration (ETo) and soil matric potential (Ψw). Two experiments were conducted, one in a greenhouse and the other in the field, using clones and seminal plants. Soil water content, plant transpiration and reference evapotranspiration were monitored. Cocoa trees were subjected to soil moisture reduction and their transpiration decreased linearly both in the field and in the greenhouse, due to decreases in the soil matric potential beyond a critical point. In the greenhouse average transpiration could be linearly estimated as a function of ETo when Ψw was higher than –24.89 kP. Drying soil conditions resulted in a reduction in transpiration by approximately a 2 % per unit decrease in Ψw. Under field conditions; clonal plant transpiration decreased linearly beyond the critical matric potential of –65.02 kPa, while in seminal plants this reduction occurred beyond –79.48 kPa. Clonal plants were more sensitive to soil water variations with average transpiration lower than that of seminal cocoa tree plants.

Transpiration of young cocoa trees under soil water restriction

Cocoa plantations in Brazil have been expanding beyond the borders of traditional regions by implementing a strategy based on irrigation and the establishment of crops exposed to full sunlight. The quantification of transpiration is essential to the establishment and management of crops, and is the main factor in the determination of water demand. This study had as its objective the estimating of transpiration of young cocoa trees as a function of reference evapotranspiration (ETo) and soil matric potential (Ψw). Two experiments were conducted, one in a greenhouse and the other in the field, using clones and seminal plants. Soil water content, plant transpiration and reference evapotranspiration were monitored. Cocoa trees were subjected to soil moisture reduction and their transpiration decreased linearly both in the field and in the greenhouse, due to decreases in the soil matric potential beyond a critical point. In the greenhouse average transpiration could be linearly estimated as a function of ETo when Ψw was higher than –24.89 kP. Drying soil conditions resulted in a reduction in transpiration by approximately a 2 % per unit decrease in Ψw. Under field conditions; clonal plant transpiration decreased linearly beyond the critical matric potential of –65.02 kPa, while in seminal plants this reduction occurred beyond –79.48 kPa. Clonal plants were more sensitive to soil water variations with average transpiration lower than that of seminal cocoa tree plants.(AU)

Soil patterns and foliar standards for two cocoa clones in the States of Espírito Santo and Bahia, Brazil / Padrões de solo e normas foliares para dois clones de cacau cultivados nos Estados do Espírito Santo e Bahia, Brasil

The objective of this research was to establish soil patterns and foliar standards for clonal crops of cocoa CCN51 and PS1319 in the Atlantic regions within the northern Espírito Santo and southern Bahia States. Samples were collected from September to October 2015, in 45 high productive plots, being 23 plots of clone CCN51 and 22 of clone PS1319. Sufficiency ranges for soil and foliar standards were recommended for cocoa clones CCN51 and PS1319 planted in the Northern Espírito Santo and Southern Bahia states. Differences in the contents of foliar macronutrients K, Ca, Mg, S and micronutrients Fe and Mn, were verified between clones CCN51 and PS1319. Differences reported for standards from different geographical regions confirmed that these standards need to be regional and specific for different cocoa clones.(AU)

O objetivo deste trabalho foi estabelecer padrões de solo e padrões foliares para culturas clonais de cacau CCN51 e PS1319 nas regiões do Atlântico no norte do Espírito Santo e no sul da Bahia. As amostras foram coletadas de setembro a outubro de 2015, em 45 parcelas de alta produtividade, sendo 23 parcelas do clone CCN51 e 22 do clone PS1319. As faixas de suficiência para solo e padrões foliares foram sugeridas para os clones de cacau CCN51 e PS1319 plantados no norte do Espírito Santo e no sul da Bahia. Diferenças nos teores dos macronutrientes foliares K, Ca, Mg, S e micronutrientes Fe e Mn foram verificadas entre os clones CCN51 e PS1319. As diferenças relatadas para padrões de diferentes regiões geográficas permitem confirmar que esses padrões precisam ser regionais e específicos para diferentes clones de cacau.(AU)

CONTRIBUIÇÃO AO ESTUDO ANATÔMICO DA FOLHA E DO CAULE DO CACAUEIRO (Theobroma cacao L.)

The anatomy of the mature leaf and stem of the cacao tree is described in this study emphasizing the characterization of trichomes and secretory structures. Stem and leave ( limb and petiole) samples from the 3rd node and 5cm long young leaves were analysed. Leaf lamina is hypostomatic with anomocytic stomata. Four types of trichomes, two tectorial and two glandular occur in both limb surfaces. In the adaxial epidermis there are mucilage secretory glands. The mesophyll is dorsiventral; the palisade parenchyma is formed by two or three layers. The lacunary parenchyma has collecting cells. Along the mesophyll collateral bundles predominate involved by sclerenchymatic sheath extending up to the epidermis. Standard venation is of Camptodrome type with mixed Brochidrodomous and Eucamptodromous ramification. Petiole and stem show the epidermis with the same type of trichomes described to the limb. In their cortical and medullary parenchyma there are cells containing starch grains, idioblasts containing druses and mucilage canals. The vascular system along the petiole differentiates regarding the organization. The stem shows chlorenchyma and collenchyma layers. Sclerification of collenchyma occurs during the plant development. Discontinuous fiber ring of the primary phloem follows. Medulla is abundant and its sclerification occurs during the development.

O presente estudo teve como objetivo descrever a anatomia da folha e do caule adulto enfatizando a caracterização dos tricomas e das estruturas secretoras do cacaueiro. Foram analisadas amostras de caule e folhas (limbo e pecíolo), correspondente ao 3º nó, além de folhas novas de 5cm de comprimento. A lâmina foliar é hipoestomática, com estômatos do tipo anomocítico. Em ambas as faces do limbo ocorrem quatro tipos de tricomas: sendo dois tectores e dois glandulares. Na epiderme adaxial estão presentes as glândulas secretoras de mucilagem. O mesofilo é dorsiventral; o parênquima paliçádico é formado por duas ou três camadas. O parênquima lacunoso apresenta células coletoras. Ao longo do mesofilo predomina feixes colaterais envolvidos por bainha esclerenquimática que se estende até as epidermes. O padrão de venação é do tipo Camptodroma com ramificações mistas Brochidrodomas e Eucamptodromos. O pecíolo e o caule apresentam a epiderme com os tricomas descritos para o limbo; No parênquima cortical e medular do pecíolo e caule, há células contendo grãos de amido, idioblastos contendo drusas e canais de mucilagem. O sistema vascular ao longo do pecíolo se diferencia quanto a organização. O caule apresenta camadas de clorênquima, e de colênquima. Ocorre a esclerificação das células deste último, com o desenvolvimento. Segue-se um anel descontínuo de fibras do floema primário. A medula é ampla e se esclerifica com o desenvolvimento.

CONTRIBUIÇÃO AO ESTUDO ANATÔMICO DA FOLHA E DO CAULE DO CACAUEIRO (Theobroma cacao L.)

The anatomy of the mature leaf and stem of the cacao tree is described in this study emphasizing the characterization of trichomes and secretory structures. Stem and leave ( limb and petiole) samples from the 3rd node and 5cm long young leaves were analysed. Leaf lamina is hypostomatic with anomocytic stomata. Four types of trichomes, two tectorial and two glandular occur in both limb surfaces. In the adaxial epidermis there are mucilage secretory glands. The mesophyll is dorsiventral; the palisade parenchyma is formed by two or three layers. The lacunary parenchyma has collecting cells. Along the mesophyll collateral bundles predominate involved by sclerenchymatic sheath extending up to the epidermis. Standard venation is of Camptodrome type with mixed Brochidrodomous and Eucamptodromous ramification. Petiole and stem show the epidermis with the same type of trichomes described to the limb. In their cortical and medullary parenchyma there are cells containing starch grains, idioblasts containing druses and mucilage canals. The vascular system along the petiole differentiates regarding the organization. The stem shows chlorenchyma and collenchyma layers. Sclerification of collenchyma occurs during the plant development. Discontinuous fiber ring of the primary phloem follows. Medulla is abundant and its sclerification occurs during the development.

O presente estudo teve como objetivo descrever a anatomia da folha e do caule adulto enfatizando a caracterização dos tricomas e das estruturas secretoras do cacaueiro. Foram analisadas amostras de caule e folhas (limbo e pecíolo), correspondente ao 3º nó, além de folhas novas de 5cm de comprimento. A lâmina foliar é hipoestomática, com estômatos do tipo anomocítico. Em ambas as faces do limbo ocorrem quatro tipos de tricomas: sendo dois tectores e dois glandulares. Na epiderme adaxial estão presentes as glândulas secretoras de mucilagem. O mesofilo é dorsiventral; o parênquima paliçádico é formado por duas ou três camadas. O parênquima lacunoso apresenta células coletoras. Ao longo do mesofilo predomina feixes colaterais envolvidos por bainha esclerenquimática que se estende até as epidermes. O padrão de venação é do tipo Camptodroma com ramificações mistas Brochidrodomas e Eucamptodromos. O pecíolo e o caule apresentam a epiderme com os tricomas descritos para o limbo; No parênquima cortical e medular do pecíolo e caule, há células contendo grãos de amido, idioblastos contendo drusas e canais de mucilagem. O sistema vascular ao longo do pecíolo se diferencia quanto a organização. O caule apresenta camadas de clorênquima, e de colênquima. Ocorre a esclerificação das células deste último, com o desenvolvimento. Segue-se um anel descontínuo de fibras do floema primário. A medula é ampla e se esclerifica com o desenvolvimento.