Mário Puiatti

Alterações fisiológicas da senescência pós-colheita de brócolis

ABSTRACT - The objective of this work was to determine the early physiological changes throughoutshelf life of fresh broccoli ( Brassica oleracea L. var. italica ) cv. Piracicaba Precoce at 25 o C and relativehumidity of 96% in the dark until complete senescence. Head inflorescences showed lack of turgidityand commercial value when weight loss reached up to 5%, coinciding with 48 hour after harvest.Chlorophyll content was stable until 24 hours after harvesting; afterwards, an intense degradationphase took place. At 72 hours, total head yellowing was observed when chlorophyll content droppedto 30% of its initial content. Peroxidase activity increased by 1.4 fold during the first six hours,dropping to its lowest level approximately 24 hours after harvesting. However, from this time on, anincrement of activity was observed until 72 hours. At 24 hours after harvesting, respiration wasreduced by 50%. At later stages of senescence, respiration of florets was stable, but in a lower level thanthat determined at harvest. Sharp reduction of starch and reducing sugars was observed within 24 hoursafter harvesting, followed by continuous period of decline in starch and non-reducing sugars.Index terms: chlorophyll, peroxidase, respiration, starch, soluble sugars.ALTERACOES FISIOLOGICAS DA SENESCENCIAPOS-COLHEITA DE BROCOLISRESUMO - Alteracoes fisiologicas ocorridas durante a vida de prateleira em inflorescencias de brocolis(

Crescimento e produtividade de inhame e de milho doce em cultivo associado

An experiment was conducted to evaluate some crop production characteristics and economic viability of intercropping systems using taro (Colocasia esculenta) Chines, as major crop, and sweet corn (Zea mays) Doce Cristal as minor crop. Taro corms were planted in 12-cm-deep furrows in a 100 x 30 cm spacing. Sweet corn seeds were sowed in the row between the taro plants 40 days after the main crop planting. Corn plants were distributed in three arrays, as follows: one corn plant 30 cm apart; two corn plants 60 cm apart, and three corn plants 90 cm apart; and two growing systems (with and without removing the corn shoot when the ears were harvested at 110 days after sowing - soft kernel stage), comprising six treatments of intergrown and two control treatments (i.e., single crops). The experiments were organized in four random blocks, in a factorial array design (3 x 2) + 2 (three distribution of plants: one corn plant 30 cm apart; two corn plants 60 cm apart, and three corn plants 90 cm apart by two systems of corn growth: with and without removal of shoot when the ears were harvested + two control: single crop of either taro or sweet corn). Data for plant growth, production and the efficiency for the different planting systems arrays were collected. Both crops were suitable for intergrowing systems. Higher values for crop production and intergrowing efficiency index were obtained in treatment with one corn plant 30 cm apart. Lower intergrowing efficiency index and economical return were observed in the treatment where each three corn plants were 90 cm apart and shoots were removed just after the harvest at the soft kernel stage. The others intercrop systems were both agronomically and economically viable.

Índice SPAD para o diagnóstico do estado de nitrogênio na cultura da abobrinha

SPAD index for nitrogen status diagnosis of zucchini plants The employment of SPAD index for N status diagnosis of crops has been largely studied in recent years. However, conclusive studies about its usefulness in zucchini plants were not found in literature. The objective of this study was to evaluate the employment of SPAD index for N status diagnosis of zucchini plants (cv. Caserta). The experiment was carried out in Vicosa, Minas Gerais State, Brazil, in a randomized block design with five rates of mineral N (0, 50, 100, 200 and 400 kg/ha), with four replications. At the early flowering stage, total chlorophyll concentration, SPAD index and total N concentration in the fourth fully expanded leaf from the apex of zucchini plants were evaluated. The total chlorophyll concentration, SPAD index and total N concentration in zucchini leaves increased following a quadratic model as a function of the N rates. The estimated critical levels of total chlorophyll concentration, SPAD index and total N concentration on zucchini leaves responsible for maximum fruit yield were 5.12 mg/g of fresh matter, 55.62 units and 3.97 dag/kg of dry matter, respectively. Significant linear and positive correlation between the evaluated characteristics was observed. The results indicate that the SPAD index can be used for N status diagnosis of zucchini plants.

Divergência genética entre genótipos de pimenta com base em caracteres morfo-agrônomicos

O genero Capsicum compreende um grupo altamente diversificado de pimentas e pimentoes constituido por grande numero de especies. A caracterizacao dos materiais existentes quanto a divergencia genetica torna-se de importância fundamental visando trabalhos de melhoramento. Tecnicas multivariadas foram utilizadas para avaliar a divergencia genetica entre 34 subamostras da colecao de germoplasma de Capsicum baccatum da Universidade Federal de Vicosa. Foram utilizados cinco descritores quantitativos propostos pelo International Plant Genetic Resources Institute, em um experimento conduzido em condicoes de campo, em Vicosa-MG, no delineamento de blocos ao acaso. A divergencia genetica entre os tratamentos foi determinada pelas tecnicas multivariadas, baseadas na analise de agrupamento e de variaveis canonicas. As variaveis analisadas foram materia fresca do fruto, comprimento do fruto, espessura do pericarpo, numero de sementes por frutos e teor de solidos soluveis. Houve diferenca significativa entre as subamostras para todos os descritores avaliados. Observou-se concordância entre as tecnicas multivariadas utilizadas e foi possivel separar as subamostras em cinco grupos distintos. As subamostras BGH 1739 e BGH 1646 se destacaram apresentando bom potencial para uso em programas de melhoramento, visando a obtencao de bons materiais para consumo in natura ou para industrializacao.

Soil and leaf fertilization of lettuce crop with cow urine

The use of cow urine can be considered an agricultural practice of low cost for farmers. Nevertheless, its efficiency on crop needs research information. The present research aimed to evaluate the effect of cow urine on the growth and yield of Regina 2000 lettuce, in an experiment carried out from January 13, 2006 to March 22, 2006. The experiment was set up with 12 treatments, in a split-plot design and four completely randomized blocks. The soil and leaf applications were installed in the plot. In the split-plot, cow urine was applied at different concentrations (0.00; 0.25; 0.50; 0.75; 1.00 and 1.25 %). The plot presented four rows with 1.75 m each, in 0.25 x 0.25 m spacing. The six central plants of the two central rows formed the sampled split-plot. At harvest, the following variables were evaluated: fresh (FLM) and dry (DLM) leaf mass, fresh (FSM) and dry (DSM) stem mass, stem length (SL), fresh (FRM) and dry (DRM) root mass, fresh (FHM) and dry (DHM) head mass and commercial yield (CY). The increase in cow urine concentrations increased the performance of all lettuce characteristics, except DRM, which presented reduction, and DSM and FRM, which were not affected. The highest yield was obtained with the concentration of 1.25% (17.00 t ha-1) applied to leaves and with 1.01% (14.92 t ha-1), applied to soil, corresponding, respectively to increases of 28.1% and 47.3%, in comparison to the control. Application to leaves, in comparison to application to soil, resulted in greater FLM (0.50 and 1.25%), SL (0.50; 0.75 and 1.25%), FSM and FRM (0.5%), FHM and CY (0.50 and 1.25%), but lower DSM and FRM (1.25%) and DRM (1.0 and 1.25%). The application of cow urine solution at 1.25% to leaves or 1.0% to soil is recommended for lettuce crops.

Effect in the quality of intact and minimally processed leaves of collard greens stored at different temperatures

A conservacao de hortalicas minimamente processadas em baixas temperaturas, em associacao com o uso de embalagens adequadas, continua sendo uma das solucoes tecnologicas utilizadas para minimizar ou retardar as mudancas que ocorrem durante a conservacao. Foram estudadas as alteracoes fisico-quimicas causadas logo apos o processamento minimo e durante a conservacao de folhas de couve-comum (Brassica oleracea var. acephala) inteiras e minimamente processadas, mantidas em sacos de polipropileno de 50 µm de espessura, com perfuracoes de 810 µm de diâmetro. As folhas foram conservadas por 15 e 9 dias, a 5 e 10± 1oC, respectivamente. Logo apos o processamento minimo observou-se perda de clorofilas totais, acucares soluveis, amido e aminoacidos soluveis. As taxas de degradacao e/ou utilizacao da clorofila total, acido ascorbico, acucares soluveis e amido durante a conservacao das folhas inteiras e minimamente processadas mantidas a 5 e/ou 10± 1oC foram semelhantes, com excecao para perda de massa fresca e aminoacidos soluveis. As folhas minimamente processadas apresentaram perda de massa fresca quase duas vezes superior as folhas inteiras com nove dias de conservacao, independentemente da temperatura. Um aumento transitorio no teor de aminoacidos soluveis no final da conservacao tambem foi observado em folhas minimamente processadas. O aumento da temperatura de conservacao para 10oC potencializou as alteracoes quimicas tanto em folhas inteiras e minimamente processadas, resultando em elevadas taxas de degradacao e/ou utilizacao de clorofilas, acido ascorbico, acucares e amido, alem de estimular o acumulo de aminoacidos soluveis. E necessaria a continua busca de embalagens alternativas aquelas existentes para couve minimamente processada, associado a conservacao em baixas temperaturas, para simular as condicoes de distribuicao e comercializacao e, assim, minimizar as alteracoes fisico-quimicas que reduzem a qualidade do produto final.