André Assis Pires

BORON DEFICIENCY AFFECTS GAS EXCHANGE AND PHOTOCHEMICAL EFFICIENCY (JPI TEST PARAMETERS) IN GREEN DWARF COCONUT

Boron (B) deficiency causes a wide array of symptoms, not only among species of palms, but also within a single species (i.e. Cocos nucifera). A better understanding of the effects of B deficiency in coconut will be important to try optimizing a rational fertilization management in coconut plants. Thus, modification of PSII photochemistry (using a group of fluorescence parameters, called the JIP- test, that quantify the stepwise flow of energy through Photosystem II) and gas-exchange in boron deficient green dwarf coconut plants were investigated. Our results suggest that a modification of PSII photochemistry (non-stomatic effects) and gas-exchange (stomatic effects) were induced by boron deficiency. Such modifications are manifested by (1) increase the ratio of total dissipation to the amount of active reaction centers (RCs) [dissipation (DI)/RC] and (2) leaf-to-air vapor pressure difference (VPDleaf-air). These modifications (on PSII photochemistry and gas-exchange) were caused by a decrease in energy absorbed per excited cross-section [absorption flux (ABS)/cross section of the sample (CS0)], density of active reaction centers (RC/CS), maximal trapping rate of an exciton that will lead to QA reduction measured over a cross- section of active and inactive RCs [trapping flux (TR)/CS0], electron transport per excited cross-section [electron transport flux (ET0)/CS)], area above curve (proportional to the pool size of the electron acceptors QA on the reducing side of PSII), photosynthesis (A), stomatal conductance (gs), transpiration (E), chlorophyll concentration (SPAD readings), growth parameters (root DW and height plant). Our results demonstrate that by analyzing fluorescence (JIP test parameters) derived from the polyphasic fluorescence transients measurements were able to estimate the functional changes of PSII in B deficient coconut plants. The results in this study suggest that fluorescence analysis (JIP test) and instantaneous measurements of gas-exchange can be useful tools in assessing the physiological effects of B deficiency in green dwarf coconut.

Conteúdo de molibdênio das sementes de feijoeiro em resposta a doses do micronutriente pulverizado sobre as plantas

The objectives of this research were to verify if high Mo rates sprayed on foliage are toxic to common bean and to determine seed Mo content in response to these rates. One experiment was carried out in Coimbra, MG, in soil with pH of 5.2, where it was tested the rates of 0, 90, 1000, 2000, 3000, and 4000g ha-1 of Mo. The rate of 90 was applied at V4 phase of common bean. The rate of 1000 was applied in three ways: all at V4 phase; 1/2 at V4 and 1/2 at R5; and ¼ at V4, ¼ at R5, ¼ at R6, ¼ at R7. The rates of 2000, 3000, and 4000 were divided in four equal portions and sprayed at V4, R5, R6, and R7 phases. Mo rates had no effect on seed yield, seed mass and seed germination, indicating that Mo rates as high as 4000g ha-1 is not toxic to common bean. Mo content in seed increased from 0.007 to 6.961µg with increasing doses of Mo rates.

Rendimento de grãos, componentes do rendimento e índice SPAD do feijoeiro (Phaseolus vulgaris L.) em função de época de aplicação e do parcelamento da aplicação foliar de molibdênio

Objetivando avaliar a influencia da epoca de aplicacao e do parcelamento da dose de molibdenio, aplicado via foliar sobre os componentes da producao e indice SPAD do feijoeiro (Phaseolus vulgaris L.), variedade Meia Noite, conduziram-se dois experimentos em area da Universidade Federal de Vicosa, no municipio de Coimbra, MG, semeados em marco e julho de 2002. O delineamento experimental foi o de blocos casualizados, com dez tratamentos e quatro repeticoes. Os tratamentos avaliados foram: 1- testemunha, sem Mo; 2- 80 g ha-1 de Mo aplicados 15 dias apos a emergencia (DAE); 3- 40 g ha-1 de Mo aplicados 15 DAE e 40 g ha-1 20 DAE; 4- 40 g ha-1 de Mo 15 DAE e 40 g ha-1 25 DAE; 5- 40 gha-1 de Mo 15 DAE e 40 g ha-1 30 DAE; 6- 80 gha-1 de Mo 20 DAE; 7- 40 g ha-1 de Mo 20 DAE e 40 g ha-1 25 DAE; 8- 40 g ha-1 de Mo 20 DAE e 40 gha-1 30 DAE; 9- 80 g ha-1 de Mo 25 DAE; 10- 40 g ha-1 de Mo 25 DAE e 40 g ha-1 30 DAE. Os dados dos dois experimentos foram submetidos a uma analise conjunta. A adubacao foliar molibdica aumenta a produtividade e o indice SPAD no cultivo de verao-outono com inicio aos 15 e 20 DAE, mas nao aos 25 DAE. O parcelamento da dose nao aumenta a produtividade. No cultivo de inverno-primavera, os tratamentos com molibdenio aumentam a produtividade.

Emergência de plântulas de tomate (Solanum lycopersicum L.) em diferentes tensões de retenção de água no solo

O objetivo do trabalho foi detectar qual teor de retencao de agua no solo e mais eficiente para proporcionar emergencia das sementes de Tomate Variedade Santa Clara 5800. Os tratamentos foram compostos pela curva de capacidade de retencao de agua no solo: T1-10 KPa, T2-30 KPa, T3-70 KPa, T4-130 KPa, T5-300 KPa e T6- 1500 KPa, dispostos em delineamento inteiramente casualizado constituidos de quatro repeticoes, contendo 25 sementes cada. Foram avaliados o percentual de emergencia, velocidade de emergencia, altura de planta e massa verde da parte aerea. Os resultados foram submetidos a regressao e ANOVA a 5% de probabilidade. As maiores taxas de emergencia, velocidade de emergencia, altura de plantas e massa verde de plantas foram observadas nas menores tensoes de retencao de agua utilizadas, sendo que a tensao de 10 KPa, obteve os melhores resultados.

Evolução dos índices de desenvolvimento tecnológico na agricultura do Rio de Janeiro, 1970 a 1995

The purpose of this research was to analyze the process of agricultural modernization in the micro regions of Rio de Janeiro. The technique of factor analysis was applied to a set of variables related to the use of technologies. The results led to the conclusion that the Serrana and Nova Friburgo regions presented the greater elevation of gross index of development. This result must be associated to the predominance, in these regions, of a structure of family smallholdings, dedicated to an intensive technological activity – olericulture, as well as the importance of the pluriactivity.

Evolution rates of technological development in agriculture in Rio de Janeiro, 1970-1995

* Eng. Agronoma (UFES), D. S. Producao Vegetal (UENF), Professora do Instituto Federal do Espirito Santo (IFES) – Vitoria, ES – Brasil. E-mail: poliana@uenf.br. ** Eng. Agronomo (UFES), D. S. Economia Aplicada (UFV), Professor da Universidade Estadual do Norte Fluminense (UENF) – Campos dos Goytacazes, RJ – Brasil. E-mail: pmsouza@uenf.br. *** Eng. Agronomo (UFV), D. S. Economia Aplicada (UFV), Professor da Universidade Estadual do Norte Fluminense (UENF) – Campos dos Goytacazes, RJ – Brasil. E-mail: ponciano@uenf.br. **** Eng. Agronomo (UFES), D. S. Producao Vegetal (UENF), Professor do Instituto Federal do Espirito Santo (IFES) – Vitoria, ES – Brasil. E-mail: andre.pires@ifes.edu.br. *****Economista (UFES), D. S. Producao Vegetal (UENF), Professora da Universidade Federal Fluminense (UFF) – Campos dos Goytacazes, RJ – Brasil. E-mail: vanuzap@hotmail.com. Artigo Original

Análise da comercialização do coco ( Cocos nucifera ) produzido na região Norte Fluminense - DOI: 10.4025/actasciagron.v29i2.235

The aim of this research was to evaluate some commercialization aspects of the coconut produced in the Northern region of the State of Rio de Janeiro, as well as the transmission mechanisms of its prices between producers and wholesalers. It was evident that actual prices, both for producer and wholesale, decreased significantly during the period analyzed. The producer prices are above average from January to June and below it in the remaining months. The commercialization margins did not show trends of growth or decline in the period analyzed. Causality is from producer to wholesaler. The elasticity of price transmission was inferior to one, implying that, at moments of price rise at producer level, the margin of the wholesaler decreases, the opposite occurring in the case of a decrease in producer prices.

Análise da comercialização do coco (Cocos nucifera) produzido na região Norte Fluminense

The aim of this research was to evaluate some commercialization aspects of the coconut produced in the Northern region of the State of Rio de Janeiro, as well as the transmission mechanisms of its prices between producers and wholesalers. It was evident that actual prices, both for producer and wholesale, decreased significantly during the period analyzed. The producer prices are above average from January to June and below it in the remaining months. The commercialization margins did not show trends of growth or decline in the period analyzed. Causality is from producer to wholesaler. The elasticity of price transmission was inferior to one, implying that, at moments of price rise at producer level, the margin of the wholesaler decreases, the opposite occurring in the case of a decrease in producer prices.

Analysis of coconut (Cocos nucifera) commercialization, produced in the Northern region of the State of Rio de Janeiro.

The aim of this research was to evaluate some commercialization aspects of the coconut produced in the Northern region of the State of Rio de Janeiro, as well as the transmission mechanisms of its prices between producers and wholesalers. It was evident that actual prices, both for producer and wholesale, decreased significantly during the period analyzed. The producer prices are above average from January to June and below it in the remaining months. The commercialization margins did not show trends of growth or decline in the period analyzed. Causality is from producer to wholesaler. The elasticity of price transmission was inferior to one, implying that, at moments of price rise at producer level, the margin of the wholesaler decreases, the opposite occurring in the case of a decrease in producer prices.