Etude comparative des composés biochimiques de 12 accessions locales de piment (Capsicum annuum L.) des oasis tunisiennes

Le Capsicum annuum est parmi les cinq espèces Capsicum domestiquées (frutescens, annuum, baccatum, chinense et pubescens) le plus cultivé dans le monde. Il s'adapte assez bien, au milieu sec et chaud. Il est d’une réelle importance socio-économique, capable, de fournir une production de fruits consommés frais ou sous forme de produits peu transformés (piment conservé, piment séché, épice, etc.) de valeur nutritive élevée. L’objectif de cette recherche était d’étudier la diversité biochimique : capsaïcine, dihydrocapsaicine, fer, potassium, magnésium, sodium, zinc, flavonoïdes et acides phénoliques contenus dans une collection de piment provenant de différentes zones d’oasis en Tunisie (Gabès, Kbeli et Tozeur). La caractérisation de ces éléments a été identifié en utilisant la méthode HPLC et la spectrophotométrie d’absorption atomique. On constate une grande variabilité entre les localités de point de vue richesse en composés chimique (coefficient de variation % entre 43 et 108%). La récupération de ces anciennes provenances, qui ont été remplacé par des cultivars commerciaux provoquant une érosion génétique dans cette culture, devraient être capitale pour le maintien d’une agriculture durable

Chemical Composition and Fumigant Toxicity of Artemisia absinthium Essential Oil Against Rhyzopertha dominica and Spodoptera littoralis

Natural products are excellent alternative to synthetic pesticides due to their reduced harmful impacts on human health and environment. Pesticides based on plant essential oils or their constituents have demonstrated efficacy against a range of pests and pre- and postharvest diseases. In this study, the pesticide potentiality of the essential oils from the absinthe wormwood Artemisia absinthium (Asteraceae) was investigated against two insect pests i.e. Rhyzopertha dominica and Spodoptera littoralis. Essential oil of the aerial parts was obtained by hydrodistillation and was analyzed by GC– MS in order to determine its chemical composition. The major components identified were: camphor (24.81%), camazulene (13.17%), bronylacetate (5.89%), and myrcene (5.83%). The essential oil of A. absinthium exhibited strong fumigant toxicity against R. dominica adults, a stored product pest, with a LC50 value of 18.23 µl/l air and LC90 value of 41.74 µl/l air. The wormwood essential oil showed high fumigant activity against S. littoralis, one of the most dangerous pests of protected crops, with a LC50 value of 10.59 µl/l air and a LC90 value of 17.12 µl/l air

The challenge of using date branch waste as a peat substitute in container nursery production of lettuce (Lactuca sativa L.)

Abstract Purpose Peat-based substrates constitute the preferred media in conventional and organic nursery production. Nevertheless, in recent years, there has been a growing interest in environmental impacts associated with peat extraction that has increased with the demand of these non-renewable substrates. The re-use of organic wastes as substrate seems to be good solution to substitute commercial peat. This study evaluates date-palm peat (wastes of date-palm branches base locally known as “Kornef”) as an alternative nursery substrate. Methods The research was conducted in a completely block randomized design with a linear substitution (0, 25, 50, 75 and 100%) of peat with date-palm waste peat for transplant production of lettuce (Lactuca sativa L.). Different physicochemical parameters (porosity, bulk density, pH, and CEC) of cultivation substrates were measured. The growth parameters (leaves number, leaves area, length, chlorophyll values, fresh and dry weight of seedlings) were evaluated at the end of growth period (when the seedling reached the commercial transplanting size). Results The results showed that date-palm waste peat is an appropriate media for nursery production, showing similar properties with commercial peat and best plant response with 25 and 50% substitution. Conclusions In view of low cost, availability and large area of date-palm cultivation in Tunisia and over the world, it seems that peat can be replaced with substrate of date-palm wastes in the horticulture sector

Etude comparative des composés biochimiques de 12 accessions locales de piment (Capsicum annuum L.) des oasis tunisiennes

Le Capsicum annuum est parmi les cinq espèces Capsicum domestiquées (frutescens, annuum, baccatum, chinense et pubescens) le plus cultivé dans le monde. Il s'adapte assez bien, au milieu sec et chaud. Il est d’une réelle importance socio-économique, capable, de fournir une production de fruits consommés frais ou sous forme de produits peu transformés (piment conservé, piment séché, épice, etc.) de valeur nutritive élevée. L’objectif de cette recherche était d’étudier la diversité biochimique : capsaïcine, dihydrocapsaicine, fer, potassium, magnésium, sodium, zinc, flavonoïdes et acides phénoliques contenus dans une collection de piment provenant de différentes zones d’oasis en Tunisie (Gabès, Kbeli et Tozeur). La caractérisation de ces éléments a été identifié en utilisant la méthode HPLC et la spectrophotométrie d’absorption atomique. On constate une grande variabilité entre les localités de point de vue richesse en composés chimique (coefficient de variation % entre 43 et 108%). La récupération de ces anciennes provenances, qui ont été remplacé par des cultivars commerciaux provoquant une érosion génétique dans cette culture, devraient être capitale pour le maintien d’une agriculture durable

Chemical Composition of Ruta chalepensis Essential Oils and their Insecticidal Activity against Tribolium castaneum

Essential oils are secondary plant metabolites well known for their defensive role in plants. Many essential oils were described as having potent insecticidal activity. In the present work, the chemical composition and the insecticidal activity of Ruta chalepensis essential oils against stored product pest Tribolium castaneum (adults and larvae) were investigated. The determination of their chemical composition was carried out by using GC-MS technique. Twenty compounds were identified and results showed that essential oil of R. chalepensis are rich on 2-undecanon (48.28%) and 2-nonanon (27%). The insecticidal activity of the indicated volatile fractions was screened against adults and larvae of T. castaneum. R. chalepensis essential oil was found to be more active against adults (LC50 = 176.075 µl/l air and LC90 = 291.9 µl/l air) than larvae (LC50= 415.348 µl/l air and LC90=685.907 µl/l air). After 24 h of exposure at the dose of 200 µl/l air, 14% and 60% of mortality were recorded for larvae and adults, respectively. These preliminary findings may be useful for further studies of R. chalepensis essential oil use against other food storage pests and for deeper investigations on their mode of action