In vitro propagation of Plant Genetic Resources is a basic step for routine genebank and biotechnology research activities. Accelerating growth and rooting of in vitro plants contributes to an improvement in process efficiency and plant quality. In the present study the effect of supplemental thiamine and explant size on biometric variables, ion content in plant sap, chlorophyll content in leaves and moisture content in plants were assessed in a replicated trial on a group of seven in vitro sweetpotato accessions and validated in a set of other 45 accessions. It was shown that adding 0.1 mg L −1 of thiamine to modified Murashige and Skoog culture medium significantly increased plant height, root length, and number of nodes of in vitro sweetpotato shoot culture plants. No significant differences were observed for N03−, K+, Na+ and Ca++—ion content in plant sap, nor in leaf area, chlorophyll, or moisture content between plants grown with or without thiamine. Uninodal stem segments showed on thiamine-free medium a significantly lower root and plant growth, and reduced number of nodes, than plants grown from uni- and binodal segments on thiamine-supplemented medium. A subsequent experiment tested all the parameters above in a non-replicated screen with a set of 45 diverse sweetpotato accessions. With this diverse set of germplasm, the average plant and root length increased by 41 and 51%, respectively on thiamine-supplemented culture medium compared to the control treatment, confirming that supplemental thiamine is generally beneficial to sweetpotato in vitro shoot culture.

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In 1992 unprecedented measures were adopted in Venezuela to enhance the national environmental legislation: existing regulations regarding air and water pollution control, waste management, environmental impact studies and others were amended, and a new law establishing penalties against environmental offenses was adopted. Also, a mayor step in the involvement of public, environmental and industry organizations in policy development and implementation was made with the creation of a National Environmental Regulation Committee, which will review the existing regulations and will propose new ones. Petroleos de Venezuela, S.A. (PDVSA), the state oil company, contributed to the development of the new environmental measures, which allowed the company to review their strategies and to prepare a mid-term investment plan to comply with the emerging regulatory requirements. This paper summarizes the more significant aspects of the new environmental measures, the implications for PDVSA and a brief description of the company's mid-term investments in environmental protects. PDVSA has invested US$ 350 millions in the last 5 years to meet the requirements of the Venezuelan regulations, and have planned to invest US$ 800 million for the period 1994–2000. Introduction Petroleos de Venezuela, S.A. (PDVSA) is carring out a medium-term energy expansion plan which contemplates an increase of the development of Venezuela's energy resources on several fronts during the present decade. This expansion plan will take place in a setting of increasing environmental restrictions and ecological conservation not only in the oil markets but in Venezuela also. Conscious of all these new environmental restrictions, PDVSA has revised the strategy to assure that existing and future installations will be operated with due care to prevent adverse ecologial consequences. ENVIRONMENTAL REGULATIONS IN VENEZUELA Environmental policy was first fully articulated in Venezuela in the mid-1970's. Before this period environmental regulations were characterized by a weak and uneven policy framework, fragmentation of responsibilities across many ministries and little public pressure on government and industries to address environmental conservation. The main laws enacted before the 1970's included the Law of the Forests (1910), the National Public Health Law (1938), the Continental Shelf Law (1961) and the Forest, Soil and Water Conservation Law (1965). In 1976, the Venezuelan Congress enacted the Organic Law of the Environment (hereafter the Organic Law), establishing a guidance for subsequent, specific norms and actions. THE ORGANIC LAW OF THE ENVIRONMENT The overall purpose of this law if to conserve, protect and improve the environment for the benefit of quality of life in the country. P. 281^

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