Strategic Options for Small-Scale Maize Seed Systems Development in West and Central Africa Policy Brief

Seed can play a critical role in increasing agricultural productivity. It is an essential, strategic and an inexpensive input that often determines crop yields and the productivity of all other agricultural inputs

Small-scale Maize Seed Production in West and Central Africa: Profitability, Constraints and Options

There is general agreement among national governments and foreign aid donors that the food security situation in most developing countries is worsening. In the African region, almost half the population is being considered to be food insecure. To achieve food security, a country must be able to grow sufficient food. Since most developing countries rely on their agricultural production for their food security, it follows that food insecurity is mainly due to deficient agricultural production and low productivity. A main reason for this situation is that seed and planting material of adapted varieties required by farmers are not always available when needed, a situation often referred to as seed insecurity. There have been consistent efforts by the various national governments to put in place policies and programmes that ensure adequate seed supply systems (Omaliko, 1998)

Crystal structure of limonoid TS3, isolated from Trichilia rubescens

The title limonoid compound, C26H28O5·0.5H2O (TS3) [systematic name: (3aS,3bS,4aS,5aS,6S,7aR,8aR,8bS,11aR)-6-(furan-3-yl)-3a,5a,8b,11a-tetramethyl-3a,4a,5,5a,6,7,7a,8b,11,11a-decahydrooxireno[2′,3′:4b,5]oxireno[2′′,3′′:2′,3′]cyclopenta[1′,2′:7,8]phenanthro[10,1-bc]furan-3(3aH)-one hemihydrate], crystallizes with two independent molecules (1 and 2) in the asymmetric unit and one water molecule. TS3 is composed of three six-membered rings (A, C and D), three five-membered rings (B, E and F) and two epoxide rings. A group of five fused rings (A–E) is bonded to a furan ring (F) with a Csp3—Csp2 bond [1.500 (3) Å in molecule 1 and 1.499 (3) Å in molecule 2]. The absolute structures of the molecules in the crystal were determined by resonant scattering; Flack parameter = 0.05 (5). In the crystal, the individual molecules stack in columns along the b-axis direction. The water molecule bridges molecules 1 and 2 via Owater—H...O and C—H...Owater hydrogen bonds. Together with further C—H...O hydrogen bonds, linking molecules 1 and 2, the columns are linked to form slabs parallel to the ab plane. Within each column, molecules are also linked via C—H...π interactions involving the five-membered furan (F) rings

Rubescins I and J, further limonoid derivatives from the stem bark of <i>Trichilia rubescens</i> (Meliaceae)

<p>Two new tetranorterpenoid derivatives named rubescins I (<b>1</b>) and J (<b>2</b>), were isolated along with six known compounds including rubescin D (<b>3</b>), lichexanthone (<b>4</b>), scopoletin (<b>5</b>), scopoletin <i>O</i>-glycoside (<b>6</b>), <i>β</i>-sitosterol (<b>7</b>) and stigmasterol (<b>8</b>) from the stem bark of <i>Trichilia rubescens</i> (Meliaceae). The structures of the compounds were determined by means of MS, different NMR and by comparison with related data reported in the literature.</p

Assessment of the sensitivity of water resources in the intertropical zone: a bibliographical study with perspectives

Study of the vulnerability of water resources contributing to consumer health in the inter-tropical zone. The aim of this paper is to present the state of the art on the protection of water resources in the inter-tropical zone in order to identify gaps in knowledge that improve drinking water supply. To achieve this, a documentary search online was carried out to assess the progression of work over time. What emerges from this literature review is that the method for assessing intrinsic and specific vulnerability in bedrock areas is practically non-existent. A discrepancy exists and reflects the difference in a coincidence of the level of vulnerability when several methods of determining vulnerability are used in the same study site. The issue of validation is still problematic, as it lies in the fact that a property that is not precisely defined cannot be unambiguously deduced from the measured quantity. The characterisation of specific pollutants and their propagation in the saturated or groundwater zone are not taken into account. All the different components of the water cycle are not always taken into account during a groundwater vulnerability study, yet each water resource is part of a closely related component of the water cycle. HIGHLIGHTS The aim of this paper is to present the state of the art on the protection of groundwater that improve drinking water supply.; Several indices have been identified in the literature.; However, these indices reveal that groundwater vulnerability assessment procedures are not well understood, are poorly used, and remain a challenge for underdeveloped countries.; There is an urgent need to apply effective corrections to the methods of protecting water resources in the intertropical zone for drinking water supply.

Antimycobacterial cycloartane derivatives from the roots of Trichilia welwistchii C. DC (Meliaceae).

Chemical investigation of the roots of yielded a cycloartane type terpenoid 28,29-bis-norcycloart-24-en-3 ,4 ,6 -triol ( ), isolated as pure compound for the first time, three coumarins and three sterols. New cycloartane derivatives ( ) and ( + ) were obtained by hemi-synthetic reaction of compound . The structures of – were established by spectroscopic methods including 1D and 2D-NMR analysis, HR-EIMS, chemical transformations and by comparison of these data with those of related compounds. Evaluated for their antimycobacterial potential, compound and + were determined to show significant activities against MIC values of 6.25 μg mL while compound displayed weak activity showing MIC &gt; 100 μg mL . Compounds – displayed moderate activity with MIC values range from 12.5 to 50 μg mL