Carrot productivity and its physiological response to irrigation methods and regimes in arid regions

The aim of this study is to optimize water irrigation management for improving carrot productivity and water-saving in arid regions of southern Tunisia. Field studies were conducted over two seasons (2017-2019) to evaluate the effects of drip irrigation (DI) and surface irrigation (SI) methods coupled with three irrigation regimes on agronomic parameters of carrot crops. Irrigation regimes consisted of water replacements of cumulated crop evapotranspiration (ETc) at levels of 100% (I100), 70% (I70), and 40% (I40) when the readily available water in I100 treatment was depleted. Results showed a reduction in carrot yield by 13-22% and 22-32% with I70 and I40 treatments compared to I100, respectively. Yield is affected by the irrigation method with a reduction of around 6-7% under the surface method for both years. The water productivity (WP) was found to significantly vary among regimes and methods, where the highest values were observed for the I40 regimes and drip method. Drip and I100 irrigation techniques seem to optimize carrot production. Under situations of water shortage, adopting deficit irrigation treatment (DI70) could be an alternative for managing carrot irrigation and improving water productivity

Perception of drought by farmers and its impact on farming and irrigation practices Perception of drought by farmers and its impact on farming and irrigation practices

------------------------------------------------------------------------------------------ To cite th is article / Pou r citer cet article Abstract. Climate change scenarios predict negative impacts on agriculture in the southern Mediterranean regions. Preparedness for increasingly frequent droughts requires a good knowledge on how chronic water shortages may affect production and cropping systems. This work investigates recent variations in agricultural production and in cropping practices in Tunisia as induced by a rapidly changing environment. Using production statistics and climatic records over the period 1984-2005, our analysis shows that variation of the agricultural production could be explained by the Standardized Precipitation Index (R² = 0.45), and that resilience to drought could be evaluated in the same manner. Data from surveys was used to identify adjustments adopted by farmers under the pressure of water scarcity in semi arid (Nabeul) and arid (Medenine) environments. Contrasting changes in cropping systems seem to be taking place for both regions. Contrast is also observed between irrigation strategies adopted by farmers. In Nabeul, large citrus growers having access to water from canal tend to over irrigate whenever water is available in order to minimize risks of water delivery failure from public networks. In contrast small farmers using shallow wells in Medenine seek practices such as deficit irrigation and intercropping in order to optimize water use. It is our view that options to face drought under increasing environmental stress should have a dynamic nature integrating adaptive practices used by farmers. Keywords. Climate change -Agriculture production -SPI -Water scarcity -Tunisia

A comparative study on chemical profile and biological activities of aerial parts (stems, flowers, leaves, pods and seeds) of Astragalus gombiformis

The present work aims to characterize the chemical profile of phenolic compounds and some biological activities of Astragalus gombiformis. The butanolic fractions of five aerial organs (stems, flowers, leaves, pods and seeds) were quantified and identified by LC–MS analysis. The results were revealed the presence of 13 phenolic compounds (quinic acid, p-coumaric acid, transfrulic acid, Hyperoside (quercetin-3-o-galactoside, Quercetrin (quercetin-3-o-rhamonoside), Apegenin-7-o-glucoside, kampherol, Naringenin, Apegenin, Luteolin, Cirsiliol, Cirsilineol and Acacetin. In terms of biological activities, the antioxidant,α-amylase inhibitory and anticholinesterase were determined. The butanolic extract from flowers showed the highest antioxidant activity in DPPH and ABTS(IC50: 16, 43 ± 0, 46 and 16, 13 ± 0, 35 μg/mL) very closer with standards tested and week activity with Galvinoxyl radical (GOR) (IC50: 583, 95 ± 2, 20 μg/mL), while other organ's extract exhibited moderate antioxidant activity. The leaves extract was found to exhibit the highest inhibitory effect against BChE (IC50: 165,54 ± 3,49 μg/mL) compared by the other parts which give a weak inhibitory effect at 200 μg/mL. A significant alpha-amylase inhibitory activity was displayed by seeds, leaves, pods and stems extracts (IC50:76.41 ± 3.72; 74.61 ± 3.68; 88.13 ± 1.81 and 83.81 ± 1.74 μg/mL) more the standard used. Based on these results, it is right to conclude that A. gombiformis is important source of the natural anti-diabetic, antioxidants and anti-Alzheimer′s disease.The authors are grateful to the Algerian Ministry of Higher Education and Scientific Research and the National Centre for Biotechnology Research (C.R.B.T) for their respective financial and material supports

Impact of Deficit Irrigation on Yield and Fruit Quality of Orange Trees (Citrus Sinensis, L. Osbeck, CV. Meski Maltaise) in Southern Tunisia

An experiment on deficit irrigation of orange trees (Citrus sinensis, L. Osbeck, cv. Meski Maltaise) with saline water (1.5 g l‐1) was conducted in the arid region of Medenine, Tunisia. Four irrigation treatments were applied: full irrigation (FI), irrigated at 100% of the crop evapotranspiration; deficit irrigation (DI75) and (DI50), which received respectively 25 and 50% less water than FI; and the farmer's method (FM). Soil water content and salinity were monitored during the orange active period. Yield and fruit quality were measured at harvest and used to analyse water productivity (WP) and net income. Results show a decrease in soil salinity between the spring and winter seasons with maximum values observed for the DI50 treatment. Maximum yield levels were obtained under the FI treatment (26.6 t ha−1). Applying continuous deficit irrigation resulted in 24 and 45% yield reduction respectively for DI75 and DI50, compared to FI. Fruit‐quality parameters showed significant differences, with higher levels of total soluble solids for DI50 and better fruit weight for FI and FM. For total water supplies between 415 and 786 mm, WP was in the range 2.9–3.6 kg m‐3, with the highest values observed for the DI50 treatment and the lowest for FM. The soil water balance‐based irrigation method (FI) generated the greatest net income and the lowest soil salinization. Reduction in water supply produced an equivalent reduction in yield but a much stronger decrease in the economic return: using the DI75 strategy resulted in 25% water saving, 24% reduction in yield and 40% reduction in net income