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Greenhouses are used to create the appropriate environment for plant growth. Controlling the level of lighting using shading nets is one of the most commonly used methods for making suitable environmental modifications in greenhouses. The objective of this study was to examine the impact of three colored shading nets (green, black, and beige at shading rates of 50%) on inside air temperature, relative humidity, and spectral distribution of light in a greenhouse, as well as their effect on the growth and yield of strawberry plants. Data were collected during winter (December and January) and spring (March and April) months from shaded and unshaded blocks. The green net had the highest transmittance to solar radiation (τSR) during the two periods (38% and 35%, respectively) and the highest transmittance to photosynthetically active radiation (τPAR) of 34% during spring months, while the beige net had the highest τPAR of 27% during winter months. The black net had the smallest τPAR values during the two periods (22% and 29%, respectively). The lowest total light levels per season for solar radiation (SR) and photosynthetically active radiation (PAR) (746.8 and 293.7 MJ·m−2, respectively) were obtained under the black net, compared with (906.7 and 320.8 MJ·m−2, respectively) for the beige net, and (969.6 and 337.2 MJ·m−2, respectively) for the green net. The ratio of PAR to SR (PAR:SR) was 41% and 44% outside and inside the greenhouse for the control (without shade), respectively. The black net had the highest ratio of PAR:SR (39%) among the treatment nets. The green net transmitted more light in the blue–green region (400 to 570 nm) and transmitted the highest photon flux at 480 nm, while the beige net increased the infrared radiation flux from 730 nm and above and transmitted the highest photon flux at 604 nm. The study found that the green net increased the ratio of blue to red light (B/R), while the beige and green nets reduced the red to far-red light (R/FR) ratio. The photosynthetic rate, conductance to water, and transpiration were significantly higher for strawberries grown under the beige net. These results indicate that the beige net positively influenced leaf and stem characteristics, leading to improved strawberry yields. The best yields of strawberries were obtained under the beige net and the control group (no shade), surpassing the yields achieved under the black net by 26.3% and 21.4%, respectively. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A field study was conducted to understand the effectiveness of foliar applications of ZnO-NPs (0, 50, 100 mg L−1) and SiO2-NPs (0, 25, 50 mg L−1) on potato plant growth, morphology, nutrient uptake, oxidative stress, and antioxidative response under drought conditions (i.e., 100% crop evapotranspiration ETc, 75% ETc, and 50% ETc). Results revealed that water deficiency significantly hampered plant growth and biomass production and stimulated oxidative stress in potatoes. However, the exogenous application of ZnO-NPs and SiO2-NPs significantly improved plant growth attributes such as the number of branches, plant height, fresh and dry biomass, leaf area, and leaf area index as compared with untreated plants. The foliar application of ZnO-NPs (i.e., 100 and 50 mg L−1) and SiO2-NPs (50 mg L−1) promoted the mineral ion accumulation in plants grown under water deficiency and thus resulted in higher NPK, Zn2+, Fe2+, and Mn2+ contents. A significant reduction in malondialdehyde (MDA) and hydrogen peroxide (H2O2) was found in plants treated with 100 mg L−1 ZnO followed by 50 mg L−1 SiO2 and 50 mg L−1 ZnO nanoparticles as compared with untreated plants, respectively. Furthermore, the aforesaid treatments resulted in the maximum activity of antioxidant enzymes (i.e., superoxide dismutase SOD, catalase CAT, polyphenol oxidase PPO, and ascorbate peroxidase APX) under water deficit stress. Similarly, the foliar application of ZnO and SiO2 nanoparticles improved nonenzymatic antioxidants such as total flavonoid content (TFC) and total phenolic compounds (TPC) as compared with untreated plants (control). Moreover, plant growth traits were significantly and positively correlated with mineral contents, while they were negatively correlated with MDA and H2O2. ZnO-NPs and SiO2-NPs applications improved biochemical traits, which might lead to enhancements in plant tolerance and improvements in potato growth, productivity, and quality traits under water shortage conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A method for micropropagation of Conocarpus erectus through axillary shoot proliferation is presented. Shoot tips were excised from adult donor tree and cultured for 4 weeks on Murashige and Skoog's (MS) medium supplemented with 3 mg·L-1 gibberellic acid (GA3) to induce sprouting of shoots and formation of axillary shoots. Conocarpus erectus shoots were cultured for 6 weeks on MS medium supplemented with different concentrations and combinations of plant growth regulators (PGRs) and proliferation of the shoots was monitored. The type and concentration of cytokinins applied had a significant influence on shoot proliferation responses. Supplementation with 6-benzylaminopurine (BAP) increased the rate of shoot proliferation compared with other cytokinins. The use of BAP in combination with auxins such as indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA) resulted in an increased number of shoots per explant compared with treatment with BAP alone. A combination of 2 mg·L-1 BAP and 0.5 mg·L-1 IBA produced the highest number of axillary shoots (7.8 shoots/explant). The best rooting medium was full-strength MS medium supplemented with 1mg·L-1 IBA; this treatment yielded 80%rooting with an average of 3.5 roots per plantlet. All regenerated plantlets were successfully acclimatized to greenhouse conditions. [ABSTRACT FROM AUTHOR]