Ricardo Henrique Silva Santos

Growth and yield of coffee plants in agroforestry and monoculture systems in Minas Gerais, Brazil

This research compared coffee plants (Coffea arabica L.) grown in an agroforestry and monoculture systems. Data were collected during two years, on vegetative growth, reproductive development, nutritional status and yield of coffee, besides monitoring air temperature and the tree growth. All trees in agroforestry system increased in growth, resulting in a reduction in the magnitude of the diurnal temperature variation and also maximum temperature. Coffee plants in agroforestry system had less branch growth and leaf production, more persistent and larger leaves, and presented earlier flowering, with a smaller number of productive nodes and flower buds, leading to smaller berry yield than plants in monoculture system. In both systems, the coffee plants showed adequate leaf nutrient levels, except for P and K. The yield of 2443 kg ha-1 of coffee from the monoculture was greater than 515 kg ha-1 of coffee from the agroforestry system.

Produção de fitomassa, acúmulo de nutrientes e fixação biológica de nitrogênio por adubos verdes em cultivo isolado e consorciado

The objective of this work was to evaluate the effects of sole and intercropping systems of the summer green manures sunnhemp (Crotalaria juncea) and millet (Pennisetum americanum) in phytomass yield, content and accumulation of nutrients and biological nitrogen fixation (BNF). The experimental design was a randomized complete block with four replicates, and treatments consisted of green manures sunnhemp, millet, sunnhemp + millet and spontaneous vegetation. The sunnhemp stood out in the phytomass yield, being 108% greater than the spontaneous vegetation and 31% superior to millet. In the sunnhemp + millet intercropping, the leguminous contributed with 65% of the total dry matter. The presence of sunnhemp resulted in larger contents of N and Ca, while millet and the spontaneous vegetation showed larger content of potassium. The accumulation of P and Mg was strongly influenced by the phytomass yield, reaching high values in the presence of sunnhemp, while the accumulation of N and Ca was a result of the largest contents as well as the largest phytomass yield in the treatments with the leguminous. The BNF was 61% in the intercropping and 57% in sole cropping, incorporating to soil via BNF 89 and 173 kg/ha of N, respectively, being an excellent strategy for increasing soil nitrogen.

Basil conservation affected by cropping season, harvest time and storage period

O manjericao (Ocimum basilicum L.) e empregado tanto na industria culinaria quanto fitoterapica e na medicina tradicional, devido ao teor e composicao de seu oleo essencial. No entanto, o manjericao nao pode ser conservado por longo periodo apos a colheita e sua qualidade pode ser prejudicada. O objetivo deste trabalho foi verificar a influencia da epoca e do horario de colheita sobre a conservacao de manjericao armazenado por diferentes periodos. O manjericao foi colhido as 8h e as 16h em agosto/1999 e em janeiro/2000. Os ramos foram acondicionados em filmes de PVC e armazenados por 3, 6 e 9 dias. Durante o armazenamento, o teor de clorofila, e o teor e a composicao do oleo essencial foram determinados e foram conduzidas analises microbiologicas. A epoca de colheita e os dias de armazenamento influenciaram o teor final de oleo essencial. Houve decrescimo linear dos teores de oleo essencial e de clorofila e do numero de colonias de fungos e bacterias ao longo do armazenamento. Nao houve efeito da epoca de colheita ou do horario de colheita sobre a composicao do oleo essencial, mas os teores de eugenol e linalol aumentaram durante o armazenamento. O numero de coliformes ficou abaixo de 0,3 NMP g-1 e o numero de Staphylococcus aureus, abaixo de 1,0x102 UFC g-1.

Sunnhemp and millet as green manure for tropical maize production

A liberacao de nutrientes dos residuos de leguminosas e rapida nos tropicos. A consorciacao com gramineas pode resultar em liberacao de nutrientes desses residuos mais lenta e adequada aos requerimentos de N da cultura subsequente. Os objetivos do trabalho foram avaliar os efeitos dos adubos verdes crotalaria (Crotalaria juncea) e milheto (Pennisetum glaucum), solteiros ou consorciados, sobre o desempenho do milho com ou sem a aplicacao de N-fertilizante. O experimento foi instalado em quatro blocos casualizados em parcelas subdivididas. Os tratamentos da parcela consistiram do cultivo previo de crotalaria, milheto, crotalaria+milheto e ervas. Os tratamentos da subparcela foram 90 kg N ha-1 e ausencia de N-fertilizante. A parte aerea da crotalaria solteira ou consorciada apresentou, respectivamente, 173 kg ha-1 e 89 kg ha-1 de FBN-N. Metade do N foi liberado em 15 e 22 dias, dos residuos de crotalaria solteira e crotalaria+milheto respectivamente. Esta diferenca foi provavelmente causada pela imobilizacao temporaria devido a maior C/N da crotalaria+milheto. Na ausencia de N-fertilizante o cultivo previo de crotalaria+milheto resultou em maior produtividade do milho que a crotalaria solteira. Esse resultado nao se repetiu com a aplicacao de N-fertilizante. Esse efeito e atribuido a liberacao de N mais sincronizada com o requerimento do milho do que com crotalaria e milheto solteiros. O balanco de nitrogenio mostra que a recuperacao de N-FBN foi de 15% e 10% do N nos grao de milho apos crotalaria solteira e crotalaria+milheto respectivamente. A utilizacao de N-FBN pelo milho foi 65% maior apos crotalaria+milheto do que apos crotalaria solteira.

Avaliação de produtos alternativos para controle da requeima do tomateiro

The efficacy of alternative products to manage tomato (Lycopersicon esculentum) late blight, caused by Phytophthora infestans, was evaluated in three field trials (E) that compared: E1- [chili pepper (Capsicum chinense) + black pepper (Piper nigrum) + clove (Syzygium aromaticum) + turmeric (Curcuma longa) + garlic (Allium sativum) extracts]; (black pepper + clove + garlic extracts); and (clove + turmeric + garlic extracts); E2 - neem (Azadirachta indica) oil (0.5%), crude cow milk diluted in water (20% v/v), and Bordeaux mixture; E3 - homeopathic preparation (from tomato tissue infected with P. infestans - C30), the water-ethanol mixture, and Bordeaux mixture. All experiments had two controls: no sprays and metalaxyl. Severity at halfway through the epidemic (Y50); at the end of the epidemic (Ymax); area under disease progress curve (AUDPC); and disease progress rate (r) were estimated. None of the extracts reduced Y50, Ymax, AUDPC, or r values. Neem oil and Bordeaux mixture resulted in similar Y50 values (3% and 1%, respectively). Ymax (44%) in plots treated with neem was higher than in those treated with Bordeaux mixture (14%). Milk at 20% did not reduce Ymax. Values of r (0.161) and AUDPC (533) were lower with neem oil than in control (r = 0.211 and AUDPC = 1186) and similar to the Bordeaux mixture plots (r = 0.156 and AUDPC = 130). Values of r and AUDPC on plots treated with milk were similar to those in the control plots. There was no significant reduction of Y50, Ymax, AUDPC, or r values when plants were treated with homeopathic product. Bordeaux mixture was the most efficient treatment in controlling late blight. Neem oil is potentially useful. Integrated management must be implemented to keep late blight at acceptable levels on alternative tomato production systems.

Crop Interactions in Broccoli Intercropping

ABSTRACT The research goals were to evaluate crop suitability to intercropping systems, to evaluate a population density limit to successful intercropping and to study the main factors responsible for crop performance when intercropped. Three experiments were carried out during 1995 and 1996 by intercropping broccoli either with contrast crops (pea, beans, potato or oats) or with similar crops (cauliflower or cabbage) in additive and substitutive designs at different intercropping rates. The overall intercrop characteristics as leaf area index, soil coverage and biomass yield were not related to a higher yield, and similar results were due to different factors. Land Equivalent Ratios (LER) similar to 1.0 were due either to a high and constant Relative Yield (RY) of the main crop associated with low RY of the secondary crop, or to trade-off between the RY of both associated crops. Similarly, a LER of 1.34 resulted from a reasonable performance of the dominated crop (beans) in the second experiment at the 50% additive design, whereas in the third experiment there was no dominating crop in the broccoli-potato intercropping but the LER reached 1.27. The mechanisms involved in the overyielding were the bean canopy plasticity and its temporal deployment asynchrony when compared with broccoli, allowing reduction of the competition for light, and the crop development temporal asynchrony between broccoli and potato, reducing the competition for production factors.

Sustainable vegetable crop supply problem

We consider an agricultural production problem, in which one must meet a known demand of crops while respecting ecologically-based production constraints. The problem is twofold: in order to meet the demand, one must determine the division of the available heterogeneous arable areas in plots and, for each plot, obtain an appropriate crop rotation schedule. Rotation plans must respect ecologically-based constraints such as the interdiction of certain crop successions, and the regular insertion of fallows and green manures. We propose a linear formulation for this problem, in which each variable is associated with a crop rotation schedule. The model may include a large number of variables and it is, therefore, solved by means of a column-generation approach. We also discuss some extensions to the model, in order to incorporate additional characteristics found in field conditions. A set of computational tests using instances based on real-world data confirms the efficacy of the proposed methodology.

Crop rotation scheduling with adjacency constraints

In this article we propose a 0-1 optimization model to determine a crop rotation schedule for each plot in a cropping area. The rotations have the same duration in all the plots and the crops are selected to maximize plot occupation. The crops may have different production times and planting dates. The problem includes planting constraints for adjacent plots and also for sequences of crops in the rotations. Moreover, cultivating crops for green manuring and fallow periods are scheduled into each plot. As the model has, in general, a great number of constraints and variables, we propose a heuristics based on column generation. To evaluate the performance of the model and the method, computational experiments using real-world data were performed. The solutions obtained indicate that the method generates good results.

Production and vegetative growth of coffee trees under fertilization and shade levels

Em sistemas agroflorestais e dificil separar os efeitos da competicao por luz daquela por agua e nutrientes. O objetivo do experimento foi avaliar o efeito do sombreamento e do fornecimento de fertilizantes sobre o desenvolvimento vegetativo e a produtividade de cafeeiros arabica ao longo de seis anos. Os cafeeiros foram cobertos com telas sombreadoras (reducao da radiacao fotosinteticamente ativa em ate 48%) e fertilizados de 100 ate 40% da recomendacao. Foram determinados a area da folha, o numero de folhas, o numero de nos, a area foliar por ramo e a produtividade dos cafeeiros. Embora nao houvesse efeito da fertilizacao, o sombreamento influenciou o numero de nos, a area da folha e a producao a partir do terceiro ano. O numero de nos e a produtividade reduziram conforme aumentou o sombreamento. Cafeeiros sob pleno sol apresentaram maior bienalidade da producao e produtividade media de 2646 kg ha1. Cafeeiros sob 48% de sombreamento produziram em media 2094 kg ha1. Apos tres anos a area foliar aumentou com o aumento do sombreamento, tanto no final do periodo de maior quanto de menor crescimento. Nos tres primeiros anos, os cafeeiros nao diferiram nas caracteristicas vegetativas ou reprodutivas devido ao sombreamento. Os efeitos do sombreamento tornam-se mais intensos apos o inicio do periodo de altas produtividades. Cafeeiros sombreados apresentam folhas maiores e menor numero de nos do que cafeeiros sob pleno sol. Nos anos de alta produtividade esta decresce com o aumento do sombreamento e a bienalidade e menos intensa nos cafeeiros sombreados.

Fenologia e dinâmica populacional da broca do café Hypothenemus hampei (Ferr.) relacionadas às fases de desenvolvimento do fruto

A dinâmica populacional da broca do cafe, Hypothenemus hampei Ferrari foi estudada em Paula Cândido, MG, Brasil (20o S; 660 m altitude, 1391 mm precipitacao anual media, 18o C temperatura media anual). Semanalmente, de novembro de 1992 a maio de 1993, acompanhou-se: os estadios de desenvolvimento fenologico dos frutos de cafe (chumbinho, verde, inicio de maturacao, cereja e seco); os numeros de frutos brocados em cada estadio fenologico; e o numero de individuos da broca em cada estadio de desenvolvimento, presentes nos frutos brocados. Verificou-se que existem no minimo tres geracoes completas da broca desenvolvendo-se durante o periodo de formacao dos frutos. A preferencia da broca para atacar frutos em diferentes estagios de maturacao e descrita por uma equacao logistica em funcao da idade dos frutos. Depois de infestarem o fruto as femeas aguardam ate o inicio da maturacao dos frutos para iniciar a oviposicao. Os resultados indicam que medidas de controle devem ser dirigidas ao periodo compreendido entre o final da safra e o inicio da maturacao dos frutos na safra seguinte, atingindo os adultos antes do inicio da oviposicao.