S U M M A R YThe effect of seven planting densities on yield and witches' broom disease incidence in hybrid cacao (Theobroma cacao) trees in the Brazilian Amazon was investigated. Data collected over a three-year period showed that it was possible to optimize regional cacao yield by high planting densities (2500 and 1666 trees ha-') and that there was no density x year interaction.However, high planting density also favoured witches' broom incidence. A growing regional interest in planting cacao clones at high planting density should be pursued with caution, since high planting densities of clones in environments under strong pressure of selection for the witches' broom pathogen, such as in the Amazon region, are still a risky strategy. Alternatives to the high planting density system are presented and discussed.

Some aspects of the micronutrients management in common bean under boron fertilization in tropical agroecosystems are still poorly understood. The aim of this work was to evaluate the physiological quality and grain production of common bean using different B sources and dose applications, cultivated under irrigated system. The experimental design was a randomized block, in a factorial scheme 2 x 5 x 3, with two sources of B (boric acid containing 17% of B applied in leaves and FTE (fritted trace elements) and BR-12 including 1.8% of B, applied on the soil) with five doses of each source: 0 (control), 2, 4, 6 and 8 kg ha-1, with three repetitions. Each plot had a total area of 5.06 m2 (2.25m x 2.25m). The stomatal conductance and transpiration were reduced by increasing B doses, mainly when boric acid was used. Results showed that application of boric acid at 8 kg ha-1 of B reduced grain production about 21%. However, application of 6 kg ha-1 FTE BR 12 on the soil promoted grain production. However, application of 6 kg ha-1 of B using FTE (fritted trace elements) BR-12 as a source on the soil, promoted higher production and differential profit (618 US$ ha-1). Therefore, these sources and doses are recommended to common beans under irrigation systems in Brazilian Savanna agroecosystems.

A pinha é uma fruta muito apreciada devido ao sabor, e pode ser propagada por sementes ou de forma vegetativa por enxertia. No entanto, a produção de mudas por propagação seminal é dificultada pela dormência acentuada das sementes. Neste aspecto, objetivou-se determinar o melhor tratamento para a superação de dormência de sementes de pinha (Annona squamosa L.), submetendo-as à associação de tratamento pré-germinativo mecânico e não mecânico. Foi empregado o delineamento experimental inteiramente casualizado em esquema fatorial 4 × 2, com quatro repetições. Os tratamentos foram caracterizados por quatros tratamentos pré-germinativos não mecânicos em associação a tratamento pré-germinativo mecânico (presença ou ausência) com escarificação mecânica com lixa nº120. Os tratamentos avaliados foram: T1 – Controle sem escarificação; T2 – Escarificação mecânica; T3 - Ethrel (500 mg L-1); T4 - Ethrel (500 mg L-1) + escarificação mecânica; T5 - Água quente (60 ºC por 1 minuto); T6 -  Água quente (60 ºC por 1 minuto) + escarificação mecânica; T7 - Ácido giberélico, GA3 (1000 mg L-1); T8 - Ácido giberélico, GA 3 (1000 mg L-1) + escarificação mecânica. Avaliou-se a taxa de germinação, tempo, índice e velocidade de germinação, além do comprimento da raiz primária. Os tratamentos pré-germinativos das sementes de pinha com ácido giberélico em associação com escarificação mecânica tornaram-se os métodos mais indicados para a superação da dormência desta espécie.Palavras-chave: Annona squamosa L., fitormônios, reguladores vegetais, escarificação, anonáceas

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is one of the main pests of fruit, worldwide, and the use of population suppression method with low environmental impact is an increasingly strong requirement of the consumer market. The aim of this study was to evaluate the effect of mineral and natural films on the physical–chemical properties of grapes (Vitis vinifera L.), cultivar Itália, and oviposition behaviour of C. capitata. Fruits were immersed in suspensions (100 and 200 g L−1) of mineral (kaolin Surround®WP, kaolin 607, kaolin 608, kaolin 611 and talc) and natural films (chitosan, cassava starch, potato starch and guar gum 5.0 g L−1) and distilled water (control). After drying, fruits were exposed to C. capitata pairs of males and females for 24 h in choice and non-choice tests; the number of punctures with and without eggs, eggs per fruit and behavioural response of fly to treated and untreated fruits were recorded. Results obtained in this study are promising, given the scientific evidence that films of mineral particles such as kaolin (Surround®, 607, 608 and 611) changed the firmness, luminosity, chroma and hue angle of grapes and reduced the oviposition of C. capitata. In addition, our results also showed that natural polymers do not deter C. capitata females, but rather seem to stimulate oviposition.