Exploring the critical determinants of environmentally oriented public procurement using the DEMATEL method.

This study explores the critical determinants of environmentally oriented public procurement in Singapore, and investigates the causal relationships among the determinants that influence this procurement. Using the extant literature and basing our examination on natural-resource-based theory, we develop a conceptual framework for the implementation of environmentally oriented public procurement using three high-level dimensions and ten determinants. Sixteen interviews were conducted with 16 senior executives working in various ministries and statutory boards in Singapore who are closely involved in the public-procurement process. The decision-making trial and evaluation laboratory (DEMATEL) method, which is a multicriteria decision-making tool, is employed to analyse the interview data and information. The results of the analysis reveal that the two most critical determinants for environmentally oriented public procurement in Singapore are energy-efficiency strategy and environmental standards. These two determinants were also found to be the primary drivers of the implementation of environmentally oriented public procurement in Singapore. Through further analysis using the level of influence, a cognition map is developed to illustrate the relationships among the ten determinants. Understanding the dynamic nature of public procurement through these causal relationships is essential for the formulation of environmentally oriented public procurement implementation strategies.

Dark conditions enhance aluminum tolerance in several rice cultivars via multiple modulations of membrane sterols.

Aluminum-sensitive rice (Oryza sativa L.) cultivars showed increased Al tolerance under dark conditions, because less Al accumulated in the root tips (1 cm) under dark than under light conditions. Under dark conditions, the root tip concentration of total sterols, which generally reduce plasma membrane permeabilization, was higher in the most Al-sensitive japonica cultivar, Koshihikari (Ko), than in the most Al-tolerant cultivar, Rikuu-132 (R132), but the phospholipid content did not differ between the two. The Al treatment increased the proportion of stigmasterol (which has no ability to reduce membrane permeabilization) out of total sterols similarly in both cultivars under light conditions, but it decreased more in Ko under dark conditions. The carotenoid content in the root tip of Al-treated Ko was significantly lower under dark than under light conditions, indicating that isopentenyl diphosphate transport from the cytosol to plastids was decreased under dark conditions. HMG2 and HMG3 (encoding the key sterol biosynthetic enzyme 3-hydroxy-3-methylglutaryl CoA reductase) transcript levels in the root tips were enhanced under dark conditions. We suggest that the following mechanisms contribute to the increase in Al tolerance under dark conditions: inhibition of stigmasterol formation to retain membrane integrity; greater partitioning of isopentenyl diphosphate for sterol biosynthesis; and enhanced expression of HMGs to increase sterol biosynthesis.