No abstract

Nitrogen fertilizer application is conditioned closely by the amount of rainfall and its distribution. The current study aims at studying the effect of nitrogen (N) application rate on grain yield (GY), grain protein content (GPC), and nitrogen use efficiency (NUE) of durum wheat under Algerian semiarid conditions. Field trials were conducted during two contrasting and successive growing seasons (a dry year = 2016–2017 and a wet year = 2017–2018) on a local variety named Bousselam. A randomized complete block design (RCBD) was used with four replicates. Seven gradual treatments of fertilizer rate were studied: T1 = 0 unity of nitrogen (UN), T2 = 100 UN, T3 = 110 UN, T4 = 120 UN, T5 = 130 UN, T6 = 140 UN, and T7 = 150 UN. Results showed a significant difference between the dry and wet years. Only the GPC was higher in the dry year compared to the wet year having a difference of 2.94%. However, all other studied parameters were higher in the wet year, which resulted in a yield difference of 4.38 t ha−1. In addition, a significant effect of N rate on GY, thousand grain weight (TGW), and GPC was observed. A considerable difference between 120 UN and 150 UN was not noted in both years of study. Furthermore, the agronomic efficiency (AE) increased significantly with rainfall amount achieving a difference of 16.2 kg·kgN−1 between years. Finally, the results showed that using a high N amount led to a decrease in AE. Based on GY, apparent recovery efficiency (ARE), agronomic efficiency (AE), and marginal rate return (MRR) recorded in both years, the nitrogen application rate of 120 UN is recommended to be applied to wheat crops in Algerian semiarid conditions.

No abstract

Grapevine is an important fruit crop grown in the Chott Sidi Abdel Salam oasis in south eastern Tunisia. It provides great economic potential for the oasis population due to its higher yield and monetary returns. It, also, has a good nutritional value and is consumed fresh or in dried form. Powdery mildew represents one of the most destructive diseases affecting viticulture, especially in temperate-humid climate. It is an economically important fungal disease in the grapevine farms. This pathogen is able to differentially attack leaves and grapes, and is currently controlled with repeated applications of fungicides. This research aimed to use chemical control in order to assess the ability of contact, systemic and the combination of both routes of fungicides’ administration, at three different sampling moments to manage powdery mildew infestation of grapevines (Cv. Bazzoul Kalba), under field conditions. The experiments were conducted in the oasis of Chott Sidi Abdel Salam in southeastern Tunisia. Both Pristine WG and Vectra 10 SC allowed controlling the disease intensity of powdery mildew compared to Talendo® showing a highly significant augmentation of the inhibitory growth potential (84.26% and 88.94%, respectively at 21 days after the first fungicide application) and the protective potential (73.11% and 76.92%, respectively at 21 day). This information can be used to help grapevines growers to improve powdery mildew control and enhance marketable yields.

No abstract

Pepper is an inevitable constituent in the diets of Algerian population. Unfortunately, the local landraces are endangered by both genetic erosion and pollution. This study aimed to perform agro-morphological characterization of hot peppers (Capsicum annuum L.) accessions. Twenty one accessions collected from the east and south of Algeria were evaluated for 24 quantitative and 38 qualitative morphological characters under green-house conditions. The trial was conducted in a Randomized Complete Block Design (RCBD), with four replicates at the experimental station of the Department of agronomical sciences of Biskra University in Southeast Algeria. Significant variations in most of the traits were strikingly demonstrated using variance analysis and coefficients of variation and the number of modalities, frequencies and Shannon–Weaver diversity index (H′) values for the quantitative and qualitative characters respectively indicating the heterogeneity of the studied accessions. The correlations between the studied quantitative variables showed that the yield parameters were correlated with the variables related to the vegetative part of the plant. The first five PCs explained 76.877 % of the total variation and identified the most discriminant variables related particularly to yield and fruit characteristics contributing to PC1: fruit width; fruit index; fruit weight, number of locules; placenta length, pedicel length, anther length, leaf width and plant height /stem length ratio. For several qualitative traits, an important degree of variability was observed. The first factorial dimension explained 42.5% of the variance and was mostly associated with: plant height; growth habit; flower position; corolla shape; number of flower per axil and fruit shape at pedicel attachment and at blossom end; calyx margin. Cluster analysis of the combined data grouped the pepper landraces into four clusters regardless of the localities and the closest accessions belonged to different localities and/or provinces. This study notably confirms the presence of considerable genetic diversity within and between accessions of hot pepper in Algeria and provides a basis for its active conservation and future selection to develop improved local pepper populations

This work aimed to study the effect of convection drying on bioactive substances and on the texture profile of red pepper. Four mathematical models were used to model the drying kinetics, as a function of the temperature and the thickness of slices. These models are largely in agreement with experimental data. Effective diffusivity, Arrhenius constant, activation energy and thermal properties changed with temperature of dry process. The two varieties of pepper used in this work demonstrated a very high degree of spiciness (144799.37-160899.37 SU). This property is related to the high contents of capsaicin (39.60-44.01 mg/g) and dihydrocapsaicin (32.33-35.95 mg/g). Our results revealed that brittleness, hardness 1 and 2, firmness, chewiness, gumminess appearance and Young’s modulus are very important attributes in determining the textural profile of dried red pepper. Also, drying causes a strong degradation of natural pigments of red pepper and consequently decreases attractiveness of the texture profile. To avoid that, red pepper should be pretreated before the application of hot air drying.