Journal of the Saudi Society of Agricultural Sciences最新文献

The aim of this study was to assess the effect of nitrogen mineral fertilizer on the vegetative growth of citrus as well as on the densities and population dynamics of the main aphid species Aphis spiraecola Patch (Hemiptera, Aphididae). Two trials were conducted on clementine trees, Citrus clementina Hort. ex Tan., in 2016 and 2017 in Tunisia. The quantities of nitrogen delivered varied from the control to the triple recommended dose of nitrogen (3ARD) in a complete randomized block design. Results showed that all vegetative growth parameters evaluated for the clementine trees responded positively to the amount of nitrogen supplied. The highest values were obtained with the highest Nitrogen doses in both years. A positive response also was observed for aphids for all doses, with densities increasing proportionally to Nitrogen inputs. The highest dose (3ARD) increased aphid populations by 3 times compared to the control. The aphid population dynamics differed between the two years, probably under the influence of other factors such as rainfall. Thus, too much nitrogen should be avoided in citrus orchards. The control of aphids with the aim to reduce insecticide sprays cannot be separated from the management of nitrogen fertilization.

Global olive oil demand is rising; hence production has been expanding, resulting in a considerable liquid waste known as olive mill wastewater (OMW) or Zibar, which has an adverse environmental impact as it contains a variety of pollutants. Proper control and treatment before disposal are essential. This study reviews the availability of international legislation and alternative techniques implemented worldwide to ensure safe OMW disposal and its applicability in hot climatic regions. Safe OMW disposal provides sustainable waste management throughout the entire chain of olive oil production. Three alternative techniques derived from legislations from high olive oil-producing countries have been evaluated using the strength, weakness, opportunities, and threats (SWOT) analysis by evaluating internal factors and investigating external factors to derive valuable strategies using Jordan as a case study. Those alternatives are switching to a two-phase continuous centrifugation system, land spreading, and lime pretreatment. The SWOT analyses yielded that shifting towards using a two-phase system would be a viable option for attracting funding agencies; the land spreading option can be applied if the risk of groundwater contamination is minimal, such as in the southern region of Jordan. Finally, before the evaporation ponds, lime pretreatment is a good option if the produced OMW is enormous such as the case in the northern region of Jordan, which has the highest mills number and produces a massive amount of OMW of about 66.3% of the total amount generated in Jordan.

In fluctuating thermal conditions, the survival challenge for insects is particularly difficult because their physiological activities depend upon environmental temperature. The extreme temperature or heat stress leads to the insect species' extinction and evolution in adaptation strategies. Upon extreme heat, many insect species cannot survive, because they do not possess sufficient heat tolerance during gradual heat stress in their habitat. In the current review, we demonstrated the physiological process which triggers responses toward heat stressed environments and engenders the heat tolerance capacities in ectothermic insects including the nervous system response to detect heat, metabolic mechanism in response to heat stress, silk shelters behavior during thermal changes, host plant preferences, microhabitat selection, thermoregulatory behavior and thermal acclimation response under the heat stress. This review highlighted that besides the insect’s responses regulated by varied physiological mechanisms, heat shock proteins (HSPs) still needs proper investigations. Entrenched in geographical distributions and microhabitat selection, we discussed the adaptation strategies and physiological and behavioral mechanisms that evolved due to heat stress. Many insect species cope with heat stress with the help of phenotype plasticity and genetic variations. The plasticity mechanisms are not sufficient alone to avoid extreme temperatures in insect populations. There is still need to explore how insects respond to thermal changes by using advanced genetic variation methods in both hot and cold-adapted insect species. This review enriched the new insight to improve the researcher’s understanding of distinct responses and evolutionary consequences of insect responses and thermal adaptations under the changing climate.

The poor dispersibility of coconut protein (CP) as a byproduct of industrial coconut oil production limits its use in food. In this study, we aimed to characterize the physicochemical properties of CP and improve its solubility and dispersion using pH, NaCl, and xanthan gum (XG) in the concentrations used in food. Compared with other CPs, this CP had a high fat:protein ratio, with 42% protein, 15% fat, and 32% carbohydrate (wet basis). After spray drying, increases in crystallinity and in starch–lipid interaction or starch–protein–lipid interaction in the CP powder were observed using X-ray diffraction and Fourier-transform infrared. The CP particles had a rough, irregular shape, with a wide distribution without surface cracks, and contained oil bodies. CP suspension with 2% protein was investigated. Increasing pH to 6.2 and adding 0.4–0.5 M NaCl increased the protein solubility because the pH was far from the isoelectric point, and salting-in effect occurred. However, precipitation of the CP suspension was observed. Adding 0.4% XG to CP suspension produced fluid-like behavior without precipitation by increasing the viscosity and the negative charge of surface particles. Thus, a CP–XG suspension with 2% protein could be used in the food industry, such as in protein drinks.

In this study, the resistance of selected canola genotypes to the mustard aphid Lipaphis erysimi (Kaltenbach) was investigated. Molecular characterization of plant resistance was conducted, and genetic variability was observed between the resistant (KS-75) and susceptible (Abaseen) genotypes of brassica. Three RAPD markers were identified that were associated with the resistance. This study was conducted to compare the genetic data between two genotypes (KS-75 resistant and Abaseen susceptible), with an average of 4.3 bands per primer. The amplification bands per primer ranged from 9 to polymorphic fragments of 8, with fragment sizes ranging from 450 to 1700 base pairs to 9 kilo base pairs (kbps). Amplification of the largest fragment in 9 kbps using four primers (A 1–12, B 1–12, K 1–12 and L 1–12) resulted in a mean 92 percent identity index between the first two resistant and susceptible genotypes. KS-75 resistant had the highest mean genetic diversity of 92 percent, while Abaseen susceptible had the lowest mean genetic diversity of 8 percent. Out of the three markers tested, two were found to be positively associated with aphid resistance, while one was negatively correlated. These markers can be used to help develop a pre-emptive strategy for aphid resistance in brassica species, without having to simultaneously select for yield and quality related traits.

Tuta absoluta is an invasive, oligophagous pest that has been recently reported from Pakistan. Although originated from South America, it has now introduced and spread in almost all the tomato growing areas of the globe including Pakistan. Therefore, delta type pheromone traps containing synthetic 0.8 mg pheromone along with various colored light traps i.e., red, blue, golden, white, and green were evaluated for the monitoring and management of T. absoluta. Weekly observations were taken for the mean capture of T. absoluta moths in traps along with mean infestation percentage on leaves, stems and fruits of tomato. Results indicated that all the traps were found effective to attract T. absoluta moths, but they vary in their effectiveness to capture moths. Pheromone traps capture only males, whereas light traps attracted both the sexes. Significantly the highest number of males were captured in female synthesized pheromone traps, followed by golden color light traps, whereas red color light traps capture least number of males. Males captured in blue, white, and green color light traps were not significantly different from each other. Significantly the highest number of females were captured in golden color light traps, followed by blue color trap, whereas females capture in white and green color light traps were not significantly different from each other. The least number of females were captured in red color light traps. The tomatoes grown in golden color light and pheromone traps significantly suffered the lowest infestation, followed by blue, white, and green color light traps, whereas maximum damage was observed in red color light trap treatment. Only temperature showed a significant but very weak influence on the performance of various traps to attract T. absoluta moths. Therefore, studies should be undertaken to evaluate various combination of light traps with pheromone to maximize the capture T. absoluta moths, that could not only help in its early monitoring and detection but could lead to its mass destruction.

‘Mejhoul’ date cultivar originated from Morocco and largely spread around the world. It is of high commercial value and is considered to be one of the best-exported dates concerning its fruit quality and size in comparison with other cultivars. This study aims to investigate variations within the physicochemical and microbiological characteristics of ‘Mejhoul’ dates sampled from its original growing areas in Morocco and other countries, where the cultivar is expanded in the recent years. Dates samples were collected from the most important production areas of the ‘Mejhoul’ cultivar in Morocco (Figuig, Bouanane, Boudnib, Difat Ziz, Rissani and Zagora) and the United States of America, Kingdom of Saudi Arabia, Jordan and Palestine. Variance analysis of pH, moisture, ash and sugar content show a significant difference (p < 0.05) within ‘Mejhoul’ cultivar samples. Statistical analysis (Principal Component Analysis “PCA”) allows the classification of samples into three groups. The first group holds ‘Mejhoul’ samples from Morocco, including Figuig, Boudnib and Difat Ziz, characterized by high water content and high density of TVC and Yeasts. The second group is composed of all international samples (Palestine, Jordan, USA and KSA) in addition to samples from Rissani (Morocco), presents reverse characteristics compared to the first group. The third group includes ‘Mejhoul’ from Bouanane and Zagora (Morocco). Despite the availability of favorable conditions, making Morocco an ideal area for ‘Mejhoul’ production. However export of this date cultivar remains limited from Morocco due to uncontrolled production techniques and environmental factors.

Due to global warming, animal’s heat tolerance and adaptability characteristics to hot environmental conditions are attracting more research interest. The current experimental study was actually designed to evaluate and compare the heat tolerance efficiency of two purebred Saudi sheep when exposed to heat stress conditions under a biometeorologically-simulated environment similar to Kingdom of Saudi Arabia (KSA) semi-arid environment. A total of 20 healthy male growing lambs of Najdi and Naimi breed with an initial body weight of 24.71 ± 4.65 Kg and 4 month-old were used in a 2-phases experiment. During the preliminary phase (lasted for 3 weeks), lambs were placed under a stable thermoneutral condition. Meanwhile, simulation of the external environment was performed using climatic-controlled chambers during the experimental phase (lasted for 8 weeks). Several meteorological [ambient temperature (Ta), relative humidity (RH) and temperature humidity index (THI)] and thermophysiological [rectal temperature (Tr), skin temperature (Tsk), respiratory rate (RR), heat tolerance coefficient (HTC), adaptability coefficient (AC), internal (BTG_in), external (BTG_ex) and total (BTG_to) body thermal gradients] measurements were recorded at weeks 0, 4 and 8. The obtained meteorological data showed that the prevailed conditions in the climatic chamber exhibited (P < 0.05) elevated values compared to the chambers with control or thermoneutral conditions, which indicated that all lambs had undergone a different level of surrounding conditions, which was our goal in the first place. Notably, the obtained findings of all variables showed irrespective to the breed the same trend as they all were affected (P < 0.05) at the 4th weeks and slowly returned to their steady values by the 8th weeks, especially body temperatures. Under such hot climatic condition, lambs showed as well some breed difference, where Naimi lambs kept in eliciting (P < 0.05) higher values of RR, AC, and BTG_to as well as lower values of HTC compared to their Najdi associates. In conclusion, the outcomes might collectively enable us to initially recommend selecting Najdi breed over Naimi breed for herding under the hot environmental conditions of KSA. However, identification of genes responsible for acquiring heat tolerance ability of Najdi compared to Naimi is highly recommended in future studies.