The aroma and fragrance industry is a billion-dollar world market which grows annually. Essential oils comprise the majority of compounds used by these industries. These sets of metabolites are formed mainly by monoterpenes, which are products of the plants' secondary metabolism. Biosynthesized from mevalonate and methylerythitol phosphate, the essential oil production depends not only on genetic factors and the developmental stage of plants, but also on environmental factors which could result in biochemical and physiological alterations in plants modifying the quantity and quality of the essential oil. These modifications impair aromatic plant production aimed at essential oil by reducing their quality. It is desirable to develop techniques of agronomical management to improve essential oil products and their specific compounds. Among other factors influencing essential oil production are plant growth regulators or plant hormones. Endogenous levels as well exogenous application could affect essential oil production and chemical composition. In this review we will present research in which plant growth regulators or their synthetic analogs were used and their effects on essential oil production.

Objetivando caracterizar morfologicamente acessos de batata-doce da Coleção de Germoplasma da UENF e visando otimizar a utilização de genomas de interesse para o melhoramento, foram instalados dois experimentos, ambos em blocos ao acaso com três repetições. Os plantios foram realizados em novembro e em dezembro de 1997, ambos na cidade de Campos dos Goytacazes (RJ). Para tanto, quatorze acessos de batata-doce foram avaliados quanto a descritores da parte aérea e das raízes, num total de vinte características. Constatou-se a ocorrência de variabilidade genética entre os acessos, proporcionada principalmente pelas características pubescência do ápice das ramas, pigmentação das nervuras inferiores da folha e formato das raízes. Os acessos 'Amarelinha', 'Roxinha', 'WON-B' e 'Campina 3' apresentaram características de interesse para o mercado consumidor Norte- Fluminense.

To characterize morphologically accesses of sweet potato from the germplasm collection of the Universidade Estadual do Norte Fluminense (UENF) Brazil, as a way to optimize the utilization of important genomes for plant breeding, two experiments were carried out in field conditions, both in a randomized blocks design with three replications. The experiments were done in November at UENF and December in Campos. For such experiment, fourteen sweet potato accesses were evaluated for different traits related to aerial parts, and root descriptors, in a total of twenty characteristics. Genetic variability between accesses was observed, mainly due to characteristics of pubescence of the stem apex, pigmentation of the inferior veins of leaves and shape of roots. The accesses, Amarelinha, Roxinha, WON-B and Campina 3 presented interesting characteristics for the market of north-fluminense region.

O experimento foi realizado em condições de campo, na Fazenda Experimental da EPAMIG, em Ponte Nova-MG, no período de janeiro a julho de 1995, com o objetivo de avaliar o efeito de doses de dejeto de suínos na forma líquida, sobre a produção de batata-doce, cultivar Paulista, na incidência de plantas daninhas e na eficiência de controle de espécies de plantas daninhas pelo metribuzin. Utilizou-se o delineamento em blocos ao acaso, no esquema fatorial, com quatro repetições. Foram avaliados os efeitos das doses 0, 20, 40 e 60 m3 ha-1 de dejeto de suínos combinadas com 0, 300, 600 e 900 g ha-1 de metribuzin. Houve incremento linear de biomassa fresca das plantas daninhas de folhas largas, plantas de folhas estreitas e total de plantas daninhas em função do aumento das doses dejeto de suínos. O metribuzin foi seletivo para a cultura de batata-doce, não sendo observado nenhum sintoma visível de fitotoxicidade à cultura e eficiente no controle das principais plantas daninhas presentes na área. A produção máxima de raízes comerciais (22,94 t ha-1) foi obtida com o metribuzin na dose 810,17 g ha-1. Isto representou cerca de 89% superior ao peso obtido pela testemunha sem tratos culturais. Esta produtividade foi semelhante àquela observada nos tratamentos que receberam três cultivos. As plantas daninhas interferiram negativamente nas principais características avaliadas de produção da batata-doce. A cultura da batata-doce respondeu positivamente a adubação com dejeto líquido de suínos, com aumento linear da produção de raízes das classes extra A, comercial e total. Verificou-se também que houve correlação negativa entre plantas daninhas e as principais características de produção da cultura de batata-doce.

This study was carried out under field conditions during the period from January to July 1995 at EPAMIG Experimental Farm, in Ponte Nova/MG, aiming to evaluate the effects liquid swine manure doses on the yield of sweet potato cv Paulista, weed incidence and the weed control efficiency by metribuzin. A randomized block design in the factorial scheme with four replication was used. The effects of 0, 20, 40 and 60 m3 ha-1 doses of swine manure combined with metribuzin 0, 300, 600 and 900 g ha-1 and four weeded controls fertilized with 0, 20, 40 and 60 m3 ha-1 of swine manure were evaluated. A linear increment in fresh biomass was observed on large leaves weeds, narrow leaves and total weeds as a function of the increase in swine manure doses. Metribuzin was selective for the sweet potato crop, and no apparent sign of toxicity to this culture was observed. The maximum commercial root yield was obtained using 810.17 g ha-1 of ametribuzin dose (22.94 t ha-1, approximately 89% above the weight obtained by the control without cultivation tracts). This productivity was similar to that observed in the treatments which received three cultivations. The weeds interfered negatively with the main characteristics evaluated in the sweet potato yield. The sweet potato crop answered positively to the fertilization with liquid swine manure presenting a linear increase in root production of the extra A, commercial and total classes. Also it was verified the occurrence of a negative correlation between weeds and the main yield characteristics in the sweet potato cropping.