Variations in the morphological characteristics of Stipa tenacissima fiber: The case of Tunisia

Esparto fibers are cellulose-based fibers extracted from esparto (Stipa tenacissima) leaves. Morphological characteristics (length, width, and coarseness) of esparto fibers are analyzed in relation to growing conditions and plant biology. Seven localized sites in Kasserine in central western Tunisia are examined. The analysis of variance showed that all investigated characteristics vary significantly with site, season, and leaf level. Leaves reach minimum level in winter and maximum level in fall. Fiber differentiation is closely related to the vegetative cycle. Fibers are short and wide at the leaf base (basal level) and grow longer and thinner above the leaf. Results on the raw material (esparto leaves) were confirmed by results on esparto pulp.     

Bacterial Populations of African Catfish,Clarias gariepinus (Burchell 1822) Cultured in Earthen Ponds

The aim of this study was to investigate the load and distribution patterns of the aerobic bacterial flora associated with pond water, sediments, gills, and intestines of healthy African catfish, Clarias gariepinus, cultured in Saudi Arabia. Counts of viable bacteria ranged from 7.9 ± 4.4 10³ to 4.3 ± 5.7 10⁴ colony forming units (cfu)/mL in water; 1.3 ± 2.7 10⁸ to 7.4 ± 4.6 10⁹ cfu/g in sediments; 8.7 ± 1.8 10⁶ to 6.6 ± 5.8 10⁷ cfu/g in gill filaments; and 8.8 ± 6.2 10⁸ to 4.3 ± 2.8 10¹⁰ cfu/g in intestines. The bacterial flora was predominantly comprised of gram-negative rods, accounting for 75% of the total isolated strains. Altogether, 11 bacterial species of 8 genera were identified: Aeromonas hydrophila, Shewanella putrefaciens, Vibrio cholerae, Staphylococcus sp., Corynebacterium urealyticum, and Vibrio vulnificus were the most common with the first three dominating (prevalence > 14%) in every population studied.     

FRESHWATER PRAWN FARMING IN GHER SYSTEMS IN SOUTHWEST BANGLADESH

The livelihoods of a large number of farmers are associated with freshwater prawn (Macrobrachium rosenbergii) farming in gher (modified rice fields with high, broad peripheral dikes) systems in southwest Bangladesh. Most farmers integrated prawn with fish and rice in their gher and followed extensive methods using low inputs. Although farmers have improved their social and economic conditions through prawn farming, constraints include high production costs, low supply of wild fry and snail meat as prawn feed, lack of technical knowledge of farmers, and negative environmental impacts.     

Genetic model analysis on seedling and maturity traits in wheat under rainfed conditions

An experiment was conducted to access the genetic variability among early vigour and quantitative traits under limited moisture in F₂ generation of a 5 × 5 diallel cross of bread wheat. The results indicated that there was significant genotypic variation among the genotypes. Additive dominance model revealed full fitness of the data for RL, DSW, FRW, DRW, spike length, and 1000-grain weight but was partially fit for SL, FSW, R/S, tillers per seedling, plant height, tillers per plant, spikelets per spike, and grain yield per plant. The partially adequate models for these plant characters might be due to the presence of non-allelic interaction, linkage, and non-independent distribution of the genes in the parents. Additive genes coupled with moderate to high narrow sense heritability were involved in the heritage of all the traits, which indicated a higher scope of selection in early generations.     

Passive immunity in tiger shrimp (Penaeus monodon) fed with monoclonal antibody to white spot syndrome virus

A study was conducted on the stability of monoclonal antibody (MAb) in the hepatopancreas and hemolymph of Penaeus monodon and its effect on protection against white spot syndrome virus (WSSV) upon challenge. MAb C-5 raised against WSSV was purified and coated onto a commercial shrimp feed at dosages of 5, 10 and 15 mg/kg feed. The feed was fed to P. monodon and stability of the MAb in hepatopancreas and hemolymph was determined by immunodot and Western blot. Immunodot results indicated the presence of MAb for 2 h post-feeding in hepatopancreas and hemolymph which was dose-dependent. MAb was also detected in hemolymph by Western blot up to 1 h post-feeding. Shrimp fed with MAb were challenged with WSSV by oral and injection methods. In shrimp fed with 15 mg antibody/kg feed (0.45 μg MAb/g shrimp/day) WSSV infection significantly delayed both in oral and injection challenges with a survival of 65 and 70 % (p < 0.05), respectively, during 15 days post-challenge. MAb was stable in shrimp for passive immunization against WSSV and could be a potential tool for prophylaxis against the virus.     

Impact of a Variable Tungsten Pollution on the Elemental Uptake of Two Plant Species

A radish and a grass species were grown in identical substrates either unpolluted or polluted by tungsten (W) at 1, 5, and 10 μg/g levels of watering solutions during 1 month under controlled laboratory conditions. Initially, at 4.1 μg/g, the W content in grass leaves reached 16 μg/g at the highest rate of W supply to the substrate. For radish, the content of W reached 22 and 29 μg/g in the leaves and roots, respectively. The overall W pollution increased significantly the mobility of major elements from substrate to grass leaves, especially at the 5 μg/g pollution level, whereas the W impact on radish leaves resulted in an increase of most contents, only Mn remaining unaffected. The roots from polluted radishes were enriched in Si by 21% and Al by 42% at low pollution, and in Si by 15% at high supply, whereas the uptake of the other elements remained unchanged. It looks like the W pollution at the levels chosen does not impact the transfer of the major and trace elements from roots to leaves of Raphanus sativus. Alternatively, metallic trace elements (Ba, Ni, Cr, Zn, W, Co) of the Raphanus sativus and Chloris gayana leaves outline similar content changes depending on the amount of W pollution. The total rare-earth element contents of the leaves of Raphanus sativus grown in the polluted substrates are lower than those of the leaves from unpolluted substrate. Their normalization in the leaves and roots of Raphanus sativus from the polluted substrates to those of the radish from non-polluted substrate provides flat patterns for both with a positive Eu anomaly for leaves, as for those of the grass and a negative Gd anomaly for roots. Also, addition of soluble W to the substrates induced an increase in the bacterial activity of the soil.     

Dynamics of macronutrients in olive leaves

The study aims to track the dynamics of the olive leaf nitrogen (N), phosphorus (P) and potassium (K) for five olive varieties under drip irrigation in farmer's fields in central Morocco. Leaf sampling was done every month from May 2014 to April 2015. Leaf macronutrients contents showed variation over time. Olive leaves have maintained the same N content throughout the study period indicating a continuing olive uptake of nitrogen. Higher leaf P absorption was observed during flowering and fruit magnification periods indicating the important P needs of olive during these periods. Olive leaf K levels were higher from September to December indicating the high K needs of olive. No variety effect was revealed on the leaf N, P and K contents. Very highly significant differences were found between the leaf N and K levels measured at different sampling periods. The leaf P concentration was statistically equal in all measuring periods.     

Remobilization and utilization of phosphorus in wheat cultivars under induced phosphorus deficiency

A solution culture study was conducted to compare the phosphorus (P) remobilization efficiency of four wheat cultivars under induced P deficiency. Wheat cultivars, i.e. Sarsabz, NIA-Sunder, NIA-Amber and NIA-Saarang were initially grown on adequate P nutrition for 30 days and then exposed to P-free nutrient solution for next 15 days to study P remobilization. Completely randomized design (CRD) with ten replicates per cultivar was employed. Cultivars varied for biomass production, P concentration, P uptake, and P utilization efficiency at both harvests. Overall, more than 75% of absorbed P was mobilized from older leaves to younger leaves as well as roots of all cultivars during P-omission period. However, cultivars could not produce significant variations (P < 0.05) in P remobilization, which implied that P remobilization was only a stress response to P deficiency in wheat cultivars and it could not be related to P utilization efficiency of these cultivars.     

Nitric Oxide Treatment and Induced Genes Role Against <Emphasis Type="Italic">Phytophthora infestans</Emphasis> in Potato

Effects of sodium nitroprusside (SNP; nitric oxide donor) treatments on enhancement of secondary metabolites production, oxidative stress mediators (\(\mathrm{O}_{2}^{-}\)) accumulation and antioxidant defense enzymes of Potato Spunta Sp. suspension culture cells elicited by a fungal extract from phytophthora infestans mycelium. The obtained data confirmed the significant increase in various oxidative burst (super oxide anion, hydrogen peroxide and total glutathione) contents. The administration of various NO concentrations strongly decreased hydrogen peroxide concentration and superoxide anion levels. Moreover, the SNP treatments regulate elicitor-induced activation of phenylalanine ammonium-lyase and total soluble phenols accumulation. The highest concentrations of NO donor sodium nitroprusside potentiated elicitor-induced H₂O₂ production. On the other hand, the lowest H₂O₂ contents coincided with elicitation regulated various activities of enzymes superoxide-dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and Phenyl alanine ammonia lyase (PAL) activity, the decrease in H₂O₂ concentration was probably due to a direct reduction interaction of NO-H₂O₂. On the other hand, the addition of these previous NO treatments affects mRNA peroxidase gene expression using RT-PCR techniques. In general, the addition of lower concentrations of nitric oxide reduce the mRNA peroxidase activity on contrary, the higher concentrations induced the mRNA peroxidase activity, which induce the hypersensitive reactions against fungus infection.     

Combined effect of deficit irrigation and potassium fertilizer on physiological response,plant water status and yield of soybean in calcareous soil

A 2-year field experiment (2013 and 2014) was conducted in calcareous soil (CaCO₃ 19.2%), on soybean grown under three irrigation regimes 100%, 85% and 70% of crop evapotranspiration combined with three potassium (K₂O) levels (90, 120 and 150 kg ha^?1). The objective was to investigate the complementary properties of potassium fertilizer in improving soybean physiological response under water deficit. Plant water status (relative water content RWC, chlorophyll fluorescence F_v/F₀ and F_v/F_m), had been significantly affected by irrigation or/and potassium application. Potassium improved growth characteristics (i.e. shoot length, number, leaf area and dry weight of leaves) as well as physiochemical attributes (total soluble sugars, free proline and contents of N, P, K, Ca and Na). Yield and yield water use efficiency (Y-WUE) were significantly affected by irrigation and potassium treatments. Results indicated that potassium application of 150 and 120 kg ha^?1 significantly increased seed yield by 29.6% and 13.89%, respectively, compared with 90 kg ha^?1 as average for two seasons. It was concluded that application of higher levels of potassium fertilizer in arid environment improves plant water status as well as growth and yield of soybean under water stress.