Summary1. Structured population models are used in a range of forms to predict the long-term behaviour of populations of economic or conservation interest. Such models rarely include density-dependence and do not account explicitly for the ordering of events within a generation. 2. We analysed a model for the harvesting of adults of the edible palm Euterpe edulis in which the role of density-dependence had been clearly defined. We modified the timing of harvesting in relation to the point in the life cycle at which populations were censused. 3. It is shown that the timing, form and intensity of harvesting are all important in determining asymptotic population behaviour. If harvesting affects only those individuals that were recorded as being adults at the start of a year, then the model predicts that all adults may be harvested without population eradication. In contrast, if harvesting also affects individuals moving from the next smaller size class during the course of a year then populations can, under some forms of harvesting, tolerate much lower levels of harvesting. 4. If density-dependence is not taken into consideration, predictions of population responses to harvesting may be erroneous. A review of transition matrices for woody plants indicates that many of these may have been derived from populations subject to strong population regulation. 5. Synthesis and applications. In the specific case of E. edulis our model shows that, although populations appear to be robust to very high levels of harvesting, when modelled as affecting only reproductive adults, this conclusion may be sensitive to varying the timing and form of harvest, and to the assumption that only reproductive individuals are removed. Structure population models used to determine levels of harvesting should account for the existence of density-dependence as well as its timing.

RESUMO -Pesquisas com a pupunheira (Bactris gasipaes Kunth) têm sido intensificadas em vários países devido ao crescente uso dessa espécie para produção agrícola de palmito, em substituição à exploração predatória de palmeiras silvestres. Por ser uma espécie ainda pouco estudada, pesquisadores utilizam diferentes caracteres para avaliar o crescimento e a produção, frequentemente medidos de formas distintas, impossibilitando assim a comparação de resultados. O presente trabalho faz uma revisão dos métodos para análise de crescimento e produção em pupunheira, e propõe a padronização de medidas a serem usadas em experimentos agronômicos e genéticos visando a produção de palmito. As medidas vegetativas essenciais são altura, número de folhas e número de perfilhos, enquanto as opcionais são diâmetro da planta, área foliar e biomassa foliar. As medidas produtivas essenciais são número de palmitos colhidos, peso e comprimento do palmito (tipo exportação), considerando-se como opcionais peso do estipe tenro (resíduo basal), peso da folha tenra (resíduo apical) e diâmetro do palmito. O uso dessas medidas, como explicadas aqui, permitirá a comparação de resultados entre experimentos em diferentes ambientes e com diferentes genótipos, bem como a estimação de vários parâmetros fisiológicos de crescimento e produção. Palavras-chave: Bactris gasipaes, análise de crescimento, medidas lineares, medidas numéricas, correlações com produção Standardization of Growth and Yield Measurements in Pejibaye Heart-of-palm ExperimentsABSTRACT -Research with pejibaye or peach palm (Bactris gasipaes Kunth) has intensified in various countries due to its increasing use in plantations for heart-of-palm production, as a substitute for the predatory extraction of wild palms. Because the species is still understudied, researchers use different traits to evaluate its growth and yield, frequently measured in different ways, making direct comparisons of experiments impossible. This paper reviews methods used to analyse growth and yield in pejibaye and proposes a set of standard measurements to be used to evaluate agronomic and genetic experiments for heart-of-palm production. The essential yield measurements are number of harvested hearts-of-palm ("palmitos") and heart-of-palm weight and length (export type only), and the optional measurements are tender stem (basal by-product) weight, tender leaf (apical by-product) weight and heart-of-palm diameter. The use of these and with different genotypes, as well as the estimation of useful growth, yield and physiological parameters.

RESUMO -A germinação rápida e uniforme das sementes, seguida por pronta emergência das plântulas são características altamente desejáveis na formação de mudas. O objetivo deste trabalho foi verificar o efeito de diferentes níveis de umedecimento do substrato vermiculita sobre a porcentagem de emergência e o vigor de plântulas de pupunheira. O umedecimento da vermiculita com água nas quantidades de 60 a 90 ml/100 g de substrato (de 0,6 a 0,9 x o peso deste em água ou 77,6 a 86,7% da capacidade de retenção do substrato em água, respectivamente) resultaram na maior porcentagem de emergência das plântulas. O umedecimento com 90 ml água/ 100 g de vermiculita resultou em maior velocidade de emergência e vigor de plântulas (comprimento, diâmetro e massa). Termos para indexação: germinação, mudas, Bactris gasipaes, vermiculita. SUBSTRATE MOISTURE LEVEL EFFECT ON SEEDLING EMERGENCY AND VIGOR OF PEACH PALMABSTRACT -The rapid and uniform germination of seeds, followed by prompt emergency are highly desirable characteristics for seedlings formation. This research aimed to determine the effect of different level of vermiculite substrate wetting on the emergency percentage and vigor of peach palm seedlings. The wetting of vermiculite with water in quantities from 60 to 90 ml/100 g of substrate (from 0.6 to 0.9 x the weight of water or 77.6 to 86.7% of the retention capacity of the substrate in water, respectively) had shown higher emergence percentage of seedlings. The wetting with 90 ml water / 100 g of vermiculite resulted in the higher speed of emergency and vigor of seedlings (length, diameter and mass).

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-SP "in memorian". 4 Programa de Pós-Graduação em Agronomia da UNESP.RESUMO -Com o objetivo de verificar o efeito da secagem parcial e do armazenamento sobre a germinação e vigor de sementes de Euterpe edulis obtidas em três épocas de produção, o lote 1 foi colhido em 10 plantasmatriz (PM), em 02/99; o lote 2 em 15 PM, em 04/00; e o lote 3 em 11 PM, em 08/00. Os frutos foram despolpados e as sementes, colocadas para secar por zero, 20 e 40 h (três sublotes), em câmara seca (temperatura de 27o C e umidade relativa de 35%). Os três sublotes foram armazenados a 10 o C, em sacos plásticos (20 mm de espessura) fechados. Durante o armazenamento, a qualidade das sementes foi avaliada a cada seis semanas, por 30 semanas, por meio das seguintes determinações: teor de água (105±3 °C/24 h), porcentagem de germinação e vigor (primeira contagem e índice de velocidade de germinação). O aumento do tempo de secagem resultou em sementes com teor de água decrescente, em torno de 14 a 21% dos valores iniciais, que se mantiveram praticamente inalterados durante o armazenamento. A germinação e vigor das sementes foram prejudicados pela secagem parcial e pelo aumento do tempo de armazenamento, de forma diferenciada entre as épocas de produção, e ambas as características dependem das condições climáticas vigentes durante o desenvolvimento e maturação das sementes.Palavras-chave: Euterpe edulis, conservação e palmito. DRYING AND STORAGE OF Euterpe edulis SEEDS ABSTRACT -The objective of this research was to verify the effects of partial drying and storage duration on the germination and vigor of three E. edulis seed lots developed under different weather conditions. Mature fruits were harvested in the palm collection from the Instituto

RESUMO: Resultados de pesquisa envolvendo aspectos fisiológicos da pupunheira (Bactris gasipaes Kunth), fruteira nativa da América Tropical, são escassos. Procurando completar essa lacuna, um experimento sob deficiência hídrica foi conduzido em casa de vegetação, durante um período de 13 dias, utilizando plantas de 12 meses de idade. O objetivo principal foi avaliar as respostas da pupunheira à deficiência hídrica. As variáveis observadas foram: taxa de assimilação de CO 2 , transpiração, condutância estomática e potencial de água das folhas. As coletas dos dados foram realizadas diariamente em laboratório e sob fluxo de 1200 µm -2 s -1 . Os resultados foram submetidos à análise de variância e de regressão. Verificou-se decréscimo no potencial de água da folha e nas trocas gasosas quando a irrigação foi interrompida por mais de seis dias. Valores mínimos foram obtidos no décimo dia, com redução de 92% da fotossíntese líquida, 87% da condutância estomática e 70% da transpiração. O menor potencial de água nas folhas (-1,9 MPa) foi também observado nesse período. Houve recuperação total de todas as variáveis dois dias após reirrigação, com exceção da condutância estomática. A diminuição da condutância estomática e a queda mais rápida da taxa de transpiração que a queda na fotossíntese, indicam a existência de mecanismos de aclimatação em pupunheira, no sentido de diminuir as perdas de água, quando sob condição de estresse hídrico moderado. Palavras-chave: Bactris gasipaes, deficiência hídrica, fotossíntese PHOTOSYNTHESIS, STOMATAL CONDUCTANCE AND TRANSPIRATION IN PEACH PALM UNDER WATER STRESSABSTRACT: Research results on physiological aspects of peach palm (Bactris gasipaes Kunth), a native fruit tree from tropical America, are scarce. Trying to fill this gap, a water deficit experiment was performed under nursery conditions during 13 days, utilizing 12 months old plants. The main objective was to evaluate peach palm responses to water deficit. The measured variables were: CO 2 assimilation rate, transpiration rate, stomatal conductance and leaf water potential. Data were collected daily in a laboratory, under a photosynthetic photon flux (PPF) of 1200 µm -2 s -1 , and studied by variance and regression analysis. Significant decreases of leaf water potential values and gas exchange rates were verified when water was withhold for more than six days.The smallest values were found at the tenth day without water replacement, with a reduction of 92% of the net photosynthetic rate, 87% of the stomatal conductance and 70% of the transpiration. By that time, the smallest measured leaf water potential was -1.9 MPa. Recovering from water stress was accomplished two days after rewatering, except for stomatal conductance. The partial closing of the stomata (decrease in stomatal conductance) and the reduction of photosynthesis, suggest the existence of an acclimation mechanism of the peach palm, diminishing water loss under moderate stress.

Compararam-se o desenvolvimento vegetativo e a produção de híbridos de palmiteiro (Euterpe oleracea x E. edulis) com seus genitores, em duas condições diferentes de cultivo, na região de Ubatuba, SP. Em ambas as situações, os híbridos apresentaram vigor e precocidade aliados à capacidade de regeneração, mostrando-se superiores à população parental em crescimento vegetativo e produção de palmito. Embora o material ainda não seja homogêneo, os híbridos interespecíficos revelaram grande potencialidade para serem usados no cultivo racional do palmiteiro.

Pejibaye or peach palm (Bactris gasipaes Kunth) is being cultivated in many countries for heart-of-palm or palmito. The estimated area of pejibaye cultivation in Brazil is over 12,000 hectares. Large amounts of nutrients are exported during harvest, and fast and constant growth is imperative for economic large-scale cultivation; hence, replacement of nutrients, based on adequate fertilization, is essential. It is known that unbalanced fertilization can cause nutritional problems in palms, impairing growth and yield. In order to identify responses of pejibaye to NPK fertilization, a long-term trial is being carried out in Sao Paulo State, Brazil. The experimental design is an (1/2) 43 incomplete factorial, with 32 treatments, with four yearly rates of N (0-400 kg N ha -1 ), P (0-200 kg P 2 O 5 ha -1 ) and K (0-200 kg K 2 O ha -1 ), split into five applications. Data collected from five-year old plants showed that shoot and root biomass varied with NPK fertilizer rates, as did root arbuscular mycorrhizal (AM) colonization. A significant and positive linear effect of N was detected for shoot biomass, whereas for mycorrhizal colonization a quadratic N effect was found. Quadratic effects of P for root biomass and shoot/root biomass were detected. Potassium produced significant negative effects on mycorrhizal colonization and shoot/root ratio, and positive effects on root biomass; a quadratic effect of K was detected on offshoot number. Nutrient interactions were only significant for mycorrhizal colonization (P*K) and for shoot biomass (N*K). Significant positive correlation coefficients were found for AM colonization with root biomass and soil organic matter, while negative correlations were found with soil pH and magnesium content. Root biomass was negatively correlated with soil pH, base saturation, calcium and magnesium. The importance of a balanced combination of macronutrients for the overall growth of pejibaye plants was emphasized. IntroductionPejibaye or peach palm (Bactris gasipaes Kunth) is cultivated in several tropical countries for heart-of-palm production, although heart-of-palm or palmito, can be extracted from other palm genera (Tabora, P.C. et al., 1993). It is basically composed of the unexpanded leaves immediately above the apical meristem. Large-scale pejibaye cultivation aiming heart-of-palm production has some especial characteristics in relation to the cultivation of this and other palms for fruit. It involves periodical and constant harvesting, with plants in a continuous juvenile vegetative stage. The speed with which above-ground biomass is renewed (due to the high suckering capacity of the species) is a good indicator of the productivity and the economic life span of this crop. The area cultivated with pejibaye for heart-of-palm purpose in Brazil is exponentially increasing since 1990 (Bovi, M.L.A., 1997). Nowadays it is estimated as over 12,000 hectares. Different ecological regions are going into cultivation and various degrees of technology and inputs are applied to this new crop...