Koffi Tozo

Elevated CO2 and/or ozone modify lignification in the wood of poplars (Populus tremula x alba)

Trees will have to cope with increasing levels of CO2 and ozone in the atmosphere. The purpose of this work was to assess whether the lignification process could be altered in the wood of poplars under elevated CO2 and/or ozone. Young poplars were exposed either to charcoal-filtered air (control), to elevated CO2 (800 μl l−1), to ozone (200 nl l−1) or to a combination of elevated CO2 and ozone in controlled chambers. Lignification was analysed at different levels: biosynthesis pathway activities (enzyme and transcript), lignin content, and capacity to incorporate new assimilates by using 13C labelling. Elevated CO2 and ozone had opposite effects on many parameters (growth, biomass, cambial activity, wood cell wall thickness) except on lignin content which was increased by elevated CO2 and/or ozone. However, this increased lignification was due to different response mechanisms. Under elevated CO2, carbon supply to the stem and effective lignin synthesis were enhanced, leading to increased lignin content, although there was a reduction in the level of some enzyme and transcript involved in the lignin pathway. Ozone treatment induced a reduction in carbon supply and effective lignin synthesis as well as transcripts from all steps of the lignin pathway and some corresponding enzyme activities. However, lignin content was increased under ozone probably due to variations in other major components of the cell wall. Both mechanisms seemed to coexist under combined treatment and resulted in a high increase in lignin content.

Bioaccumulation de certains éléments métalliques dans les produits maraîchers cultivés sur les sols urbains le long de l'autoroute Lomé- Aného, Sud Togo

Abstract Several metallic elements were analyzed by ICP—AES in 10 vegetable species cultivated in market—gardening agriculture in Lomé and its suburban, along the highway Lomé-Aného, Togo. The results showed a high accumulation of these metallic elements both in the vegetables and in the soils. Leaf vegetables accumulated higher concentration of these metallic elements than bulb or tuber vegetables. These metals could result from the air pollution due to the intense industrial activity and the high road traffic in this site and from chemical fertilizers and pesticides used by the market-gardeners. This survey stated that the metallic elements from air, could accumulate in the legumes by foliar absorption. Furthermore, this study especially pointed out that legumes cultivated in this area could be improper for human consumption.

Valeur nutrition/santé de quelques espèces de légumineuses alimentaires mineures au Togo

Abstract A study on some minor Togolese food plants shows that some « local varieties » are potentially rich in some nutritious and healthy substances. Based on a precise methodology, we point out that: - beans of Cajanus cajan local varieties are richer in proteins (206.55 ± 0.03 to 220.17 ± 0.09 mg.g−1) than those of Macrotyloma geocarpum (155.7 ± 0.07 to 172.9 ± 0.18 mg.g−1); the subunits molecular masses are between 1,7 and 83 kDa; - Vigna unguiculata local varieties beans contains more phaseolin (28.46 ± 0.65 mg.g−1) than those of Sphenostylis stenocarpa (4.91 ± 0.21 mg.g-1); - all studied beans concentration in polyphenols varies from 0.79 ± 0,06 to 2.21 ± 0,03 mg.g-1. These new data are useful for a better valorisation of the studied food minor plants.

Les facteurs influençant la germination et la multiplication de Dodonaea viscosa (L) Jacq. (Sapindaceae), une espèce médicinale rare et menacée de disparition au Togo

Abstract In spite of its multiple uses in traditional pharmacopeia, Dodonaea viscosa (Sapindaceae) is known as a rare and threatened species in the Togolese flora. In vitro studies proved its antimicrobial activities. The aim of this study is to identify some factors influencing seed germination for sustainable rehabilitation of this species.

Constraints to production and preferred traits for taro (Colocasia esculenta) and new cocoyam (Xanthosoma mafaffa) in Togo, West Africa.

Taro ( Colocasia esculenta L. Schott) and tannia (new cocoyam) ( Xanthosoma mafaffa L. Schott) are food crops cultivated in tropical and subtropical regions of Asia, Africa and Latin America. In cultivation, they are always vegetatively propagated and their production faces many constraints. Their corm is an important source of carbohydrates and leaves eaten as vegetable provide important minerals and vitamins. In Togo, although these crops are among the most important food crops in some rural areas, they appear at the country level as neglected and underutilized species (NUS) and should be promoted. However, adequate information related to production, constraints, farmers’ preferred traits and utilisation is lacking for the development of efficient breeding schemes and their sustainable preservation and use in Togo. In this paper, a focus group survey was conducted in all five ecological zones of the country to document farmers’ perceptions regarding constraints for production of these two crops and their preferred traits for production and utilization. Collected data were analysed through descriptive statistics (frequencies, percentages and means) using the Statistical Package for Social Scientists (SPSS 20) and Excel spreadsheets. Rainfall irregularity (or shortage of rainy seasons) (68.4% of responses), soil infertility (61.5% of responses) and inefficient marketing (58.7% of responses) were the most common production constraints reported. Farmers preferred early-maturity (73% of responses) and high-yield (65% of responses) as crop traits. Men are more involved in production of these crops in Togo (79% of respondents). However, the constraints and preferences reported were not gender dependent. This study showed that production of taro and tania faces many challenges in Togo. Morphological and molecular characterization of grown varieties is highly recommended to help select suitable varieties for breeding programmes. Improvements in food processing and accessibility of credit should be prioritized to generate more income for farmers and encourage production in Togo. Keywords: Agriculture, Colocasia esculenta , constraints, farmers, preferences, production, Togo, Xanthosoma mafaffa