Covering Materials Incorporating Radiation-Preventing Techniques to Meet Greenhouse Cooling Challenges in Arid Regions: A Review

Cooling greenhouses is essential to provide a suitable environment for plant growth in arid regions characterized by brackish water resources. However, using conventional cooling methods are facing many challenges. Filtering out near infra-red radiation (NIR) at the greenhouse cover can significantly reduce the heating load and can solve the overheating problem of the greenhouse air. This paper is to review (i) the problems of using conventional cooling methods and (ii) the advantages of greenhouse covers that incorporate NIR reflectors. This survey focuses on how the cover type affects the transmittance of photosynthetically active radiation (PAR), the reflectance or absorptance of NIR and the greenhouse air temperature. NIR-reflecting plastic films seem to be the most suitable, low cost and simple cover for greenhouses under arid conditions. Therefore, this review discusses how various additives should be incorporated in plastic film to increase its mechanical properties, durability and ability to stand up to extremely harsh weather. Presently, NIR-reflecting covers are able to reduce greenhouse air temperature by no more than 5°C. This reduction is not enough in regions where the ambient temperature may exceed 45°C in summer. There is a need to develop improved NIR-reflecting plastic film covers

The cientificWorldJOURNAL Review Article Covering Materials Incorporating Radiation-Preventing Techniques to Meet Greenhouse Cooling Challenges in Arid Regions: A Review

Cooling greenhouses is essential to provide a suitable environment for plant growth in arid regions characterized by brackish water resources. However, using conventional cooling methods are facing many challenges. Filtering out near infra-red radiation (NIR) at the greenhouse cover can significantly reduce the heating load and can solve the overheating problem of the greenhouse air. This paper is to review (i) the problems of using conventional cooling methods and (ii) the advantages of greenhouse covers that incorporate NIR reflectors. This survey focuses on how the cover type affects the transmittance of photosynthetically active radiation (PAR), the reflectance or absorptance of NIR and the greenhouse air temperature. NIR-reflecting plastic films seem to be the most suitable, low cost and simple cover for greenhouses under arid conditions. Therefore, this review discusses how various additives should be incorporated in plastic film to increase its mechanical properties, durability and ability to stand up to extremely harsh weather. Presently, NIR-reflecting covers are able to reduce greenhouse air temperature by no more than 5 • C. This reduction is not enough in regions where the ambient temperature may exceed 45 • C in summer. There is a need to develop improved NIR-reflecting plastic film covers

DESIGNING AN INTEGRATED COMPUTER PROGRAM FOR VEGETABLE PRODUCTION IN THE KINGDOM OF SAUDI ARABIA

Vegetable production provide great value in the agricultural production sector in the Kingdom of Saudi Arabia. Growers and agricultural engineers need a comprehensive database in Arabic lan-guage that can be available for use any time any where. Therefore, this research project was initiat-ed. The computer program was developed using Visual Basic Net 2005 which is one of the ad-vanced visual programming languages. We took into consideration easy usage and coherence be-tween all program components. Main results in-clude computer program with the data base, which includes: vegetable crops, diseases, insect pests and other pests that attacks vegetable crops, management tactics, cultural practices, irrigation requirements, planting dates, data search. Fur-thermore, field trips have been carried out to some vegetable farms in all the Kingdom regions. A digit-ized map of the Kingdom has been added to the program in addition to crop water and heat re-quirements. Various search capabilities have been developed in the program. After the completion of the program build up, verification trips have been carried out for five regions in the presence of farm-ers and extension specialists of the different direc-torate of the Ministry of Agriculture to test the accu-racy of steps used in the program. A manual for the computer program as well as leaflet on pro-gram set up and usage have been included. It is recommended to make this program available at the internet and distribute copies to the Ministry of Agriculture and its directorates as well as farmers

Engineering Melon Plants with Improved Fruit Shelf Life Using the TILLING Approach

Background: Fruit ripening and softening are key traits that have an effect on food supply, fruit nutritional value and consequently, human health. Since ethylene induces ripening of climacteric fruit, it is one of the main targets to control fruit over ripening that leads to fruit softening and deterioration. The characterization of the ethylene pathway in Arabidopsis and tomato identified key genes that control fruit ripening. [br/] Methodology/Principal Findings: To engineer melon fruit with improved shelf-life, we conducted a translational research experiment. We set up a TILLING platform in a monoecious and climacteric melon line, cloned genes that control ethylene production and screened for induced mutations that lead to fruits with enhanced shelf life. Two missense mutations, L124F and G194D, of the ethylene biosynthetic enzyme, ACC oxidase 1, were identified and the mutant plants were characterized with respect to fruit maturation. The L124F mutation is a conservative mutation occurring away from the enzyme active site and thus was predicted to not affect ethylene production and thus fruit ripening. In contrast, G194D modification occurs in a highly conserved amino acid position predicted, by crystallographic analysis, to affect the enzymatic activity. Phenotypic analysis of the G194D mutant fruit showed complete delayed ripening and yellowing with improved shelf life and, as predicted, the L124F mutation did not have an effect. [br/] Conclusions/Significance: We constructed a mutant collection of 4023 melon M2 families. Based on the TILLING of 11 genes, we calculated the overall mutation rate of one mutation every 573 kb and identified 8 alleles per tilled kilobase. We also identified a TILLING mutant with enhanced fruit shelf life. This work demonstrates the effectiveness of TILLING as a reverse genetics tool to improve crop species. As cucurbits are model species in different areas of plant biology, we anticipate that the developed tool will be widely exploited by the scientific community

Water sorption isotherms of vegetable seeds as influenced by seed species and storage temperature

The water sorption isotherms of seeds of four vegetable species; carrot, cucumber, onion, and tomato were determined using the static method of eight saturated salt solutions (relative humidity range from 11 to 98%) at four storage temperatures; 5, 15, 25, and 35°C. The water sorption isotherms of each crop exhibited a reverse sigmoid shape. When seeds were stored at low relative humidity (RH), their equilibrium moisture contents (EMC) were relatively low. At 5°C, no major changes in moisture sorption up to 80% RH. Beyond this point, a sharp increase in EMC occurred. In general, no major differences in water sorption isotherms were observed between species at low relative humidities. Differences became obvious when seeds were stored at RH higher than 60% except for seeds held at 5°C and 15°C. In general, the increase in storage temperature increased the water activity (aw) of seeds. At 97% RH, seeds held at 25 and 35 °C deteriorated before reaching equilibrium. The experimental data were fitted well with GAB and Henderson equations. Equilibrium moisture content varied from a minimum of 0.00236 (g water/g dry matter) for tomato to a maximum of 0.0388 for carrot. The correlation coefficients (0.968 to 0.999 for GAB model and 0.922 to 0.961 for Henderson model) indicated a good fit to experimental data. The GAB model fits experimental data better than Henderson model as indicated by the higher correlation coefficient values

Assessing the Effectiveness of Reflective and Diffusive Polyethylene Films as Greenhouse Covers in Arid Environments

The application of diffusive and reflective polyethylene (PE) films as greenhouse coverings in arid climates presents an opportunity to improve the microclimate of the greenhouse and achieve consistent light distribution within the crop canopy. Nevertheless, there is still a lack of understanding regarding the properties of these covers and their impact on the microclimate and the growth parameters of crops. This study aimed to assess the impact of different covers on the diffusion of beam radiation during transmission, microclimatic parameters, and growth parameters of cucumbers in each of the greenhouses they covered. In the study, three PE covers were evaluated: a reflective cover (RC), a diffusive film (DC), and a locally produced cover (LPC) as the control treatment. The covers were installed on three identical, single-span, evaporatively cooled greenhouses named GH1/LPC, GH2/RC, and GH3/DC, which were utilized for cultivating cucumber crops. The results indicated that the diffusive nature of the tested films increased the ratio of diffuse to global solar radiation (D/G) from 0.22 outside the greenhouses to 0.49, 0.42, and 0.41 inside GH1/LPC, GH3/DC, and GH2/RC, respectively. Similarly, the ratio of diffuse to direct beam radiation (D/B) showed an increase, with values of 0.95, 0.70, and 0.68 inside GH1/LPC, GH3/DC, and GH2/RC, respectively, compared to the outside value of 0.28. The DC used in GH3 showed a favorable microclimate by reducing the air temperature and improving the relative humidity. Accordingly, the vegetative growth of the cucumbers was significantly improved in GH3/DC, reflected in increases in their biomass, followed by GH2/RC and GH1/LPC. The highest crop yield (p ≤ 0.05) of 12.3 kg/m2 was achieved in GH3/DC, followed by 10.2 kg/m2 in GH2/RC and 10.1 kg/m2 in GH1/LPC. Interestingly, the LPC not only stood out as a low-cost option but also displayed excellent diffusive–radiative properties, and demonstrated reasonable growth development and productivity for the cucumber crops. Consequently, the LPC emerges as a practical and cost-effective greenhouse covering material for crop production in arid climates

Foliar Applications of ZnO and SiO2 Nanoparticles Mitigate Water Deficit and Enhance Potato Yield and Quality Traits

The yield and quality of field crops are affected by abiotic stresses such as water deficit, which can negatively impact crop growth, productivity, and quality. However, nanotechnology holds great promise for increasing crop yield, maintaining quality, and thus mitigating abiotic stresses. Therefore, the current study was conducted to examine the influences of 0, 50, and 100 mg L−1 zinc oxide (ZnO) nanoparticles and 0, 25, and 50 mg L−1 silicon dioxide (SiO2) nanoparticles on the yield and quality traits of potato plants grown under water deficit conditions (100%, 75%, and 50% ETc). Water deficit significantly reduced yield traits (average tuber weight, number of plant tubers, and tuber yield) and quality traits (tuber diameter, crude protein, and mineral content). However, it enhanced tuber dry weight, specific gravity, ascorbic acid, starch, and total soluble solids. Foliar applications of ZnO and SiO2 nanoparticles under water deficit treatments significantly enhanced yield and improved quality traits of potato plants. Moreover, significant and positive correlations were found among yield traits. Thus, it can be concluded that using ZnO NPs at 100 mg L−1 significantly improves potato productivity and quality traits by mitigating the negative effects of water deficit in arid regions.</jats:p