The experiment was conducted through two successive seasons of 2008 and 2009 at El-Bosaily farm, El-Behira governorate at the North Coastal of the Nile Delta, in Egypt. This work aimed to study the effect of three greenhouse covers (polyethylene sheet, white and black net) and three irrigation levels [80%, 100% and 120% of the potential evapotranspiration estimated according to class A pan equation (ETo)], applied by drip irrigation system, on plant growth and crop yield of Cucumber (Cucumis sativus L. cv. Reda F1). The experimental design was split-plot with three replicates. The results showed that white net greenhouse cover optimized growth and yield of cucumber plant. White net cover treatment recorded the highest vegetative growth (plant height, number of leaves, total leaves area, total fresh and dry weights), and significantly increased total yield. The highest vegetative growth was obtained by 100% ETo compared to 80 and 120% ETo treatments. The interaction among water treatment and greenhouse cover indicated the highest vegetative growth and crop yield were obtained under white net cover with 100% ETo.

Accumulation of high level of nitrate (NO3−) in leaves is a serious issue for vegetable crops like lettuce (Lactuca sativa L.). Therefore, this study aimed to limit NO3− level by adjusting the balance between fertilization and irrigation program in lettuce. In a strip plot design with three replicates, lettuce plants were grown under four fertilizer treatments and three irrigation regimes. Three organic fertilizers (biochar, compost and vermicompost), in addition to mineral fertilizer, were used. The irrigation regimes were 60, 80 and 100% of crop evapotranspiration, ETc (ETc60, ETc80, and ETc100). Nitrogen (N), phosphorus (P) potassium (K) and organic matter (OM) in soil as well as yield, N, P, K and NO3− of lettuce were estimated. Findings showed that vermicompost or biochar (with any irrigation regime) as well as compost with irrigation by ETc60 were the effective combinations for increasing K content in soil after harvest. Under irrigation by ETc80 or ETc100, vermicompost or biochar were the efficient treatments for increasing lettuce yield equaling the farmer common practice (ETc100 x mineral fertilizer). Under irrigation by ETc60, mineral fertilizer or vermicompost showed the highest lettuce leaf content of K. Moreover, ETc60 or ETc80 x mineral fertilizer recorded the maximum NO3− content of lettuce leaves. The accumulation of nitrate in lettuce leaves owing to mineral fertilizer reached about 1.24 times than that of organic fertilizers. Compost x ETc80 or ETc100 showed the minimal NO3–N accumulation, hence, high relative reductions in NO3–N accumulation as compared to the common practice (ETc100 x mineral fertilizer) were observed. In conclusion, irrigation by 80% instead of 100% of crop evapotranspiration of organically fertilized lettuce (especially with vermicompost) could be adopted since such practice recorded high lettuce productivity with low NO3− content.

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Under sandy soil conditions, increasing the efficiency of potassium (K) fertilizers is considered to be a major limiting factor for improving the productivity and quality of fruit crops. In this context, utilizing nanotechnology has emerged as a novel technique to increase the efficiency of K applications. In our study, two field trials were conducted, in two consecutive seasons (2019/2020 and 2020/2021), to compare the effects of nano-chitosan loaded with K as a foliar treatment with those of conventional soil applications of K on plant growth, yield, and quality of strawberry plants grown in sandy soil. Strawberry plants were treated with 12 different treatments, which were replicated three times in a randomized complete block design in each growing season. Potassium sulfate (K2SO4, 48% K2O) was applied to the soil at a rate of 150.0 kg acre−1 (recommended rate, 100%). Meanwhile, the spraying of nano-chitosan loaded with K was applied at 1000 mg L−1 as a control. In addition, K2SO4 was applied either individually or in combination at the rate of 112.5 or 75.0 kg acre−1 with four nano-chitosan-K dosages (250, 500, 750, and 1000 mg L−1). After harvesting, soil samples were collected and prepared to determine K fractions. As well, plant samples were collected to determine the vegetative growth parameters and the foliage content of NPK and chlorophyll. Eventually, the yield traits and quality parameters were evaluated. A principal component analysis was conducted to determine the interrelationships of the treatments’ averages and their effects on yield components and quality traits. A combined analysis was performed for the two studied seasons and the values were the mean of six replications. The results indicated that the application of common K fertilizer (150.0 kg K2SO4 acre−1) resulted in the maximum increase in soluble and exchangeable K in the soil, which was comparable to those observed with 112.5 kg K2SO4 acre−1 + 1000 mg L−1 nano-chitosan-K and 112.5 K2SO4 acre−1 + 750 mg L−1 nano-chitosan-K. The total yield, marketable yield, and fruit firmness were all significantly increased by the latter two treatments compared to the control group. Furthermore, plots treated with 112.5 kg K2SO4 acre−1 + 1000 mg L−1 nano-chitosan-K significantly increased the total soluble solids, vitamin C levels, acidity, total sugar, and anthocyanin levels in strawberry fruits. In conclusion, under sandy soil conditions, the utilization of nanoparticles could be an indispensable tool for manipulating fertilization management when cultivating strawberries. The K status of the soil was improved by applying 75% of the recommended dose of mineral K in combination with 1000 or 750 mg L−1 of nano-chitosan-K, without compromising strawberry yield or quality.

Agricultural water rationalization expressed in irrigating the plants below their requirements became a significant strategy in crop water management. However, reduction in crop productivity under low water supply is realized. Therefore, the current study aimed to diminish sunflower yield losses associated with deficit irrigation using salicylic acid (SA). During two seasons of 2019 and 2020 at El Nubaria region, El Behaira Governorate, Egypt, combinations of three irrigation regimes (100, 85 and 70% of crop evapotranspiration, denoted WR100%, WR85%, and WR70%, respectively), and three levels of SA (0.0, 0.5, and 1 mM. abbreviated as SA0.0, SA0.5, and SA1.0, respectively) on sunflower plants performance were evaluated. Treatments were arranged in a strip–plot design with three replicates. Findings revealed that treated sunflower plants with WR100% × SA1.0 contained the highest amounts of total chlorophyll and carotenoids as well as the lowest proline content. Seed yield of WR100% × SA1.0 treatment was higher than that of WR70% × SA0.0 by 109.7% in the first season and 125.9% in the second one. As averages of the two seasons, SA0.5 and SA1.0 lowered the reductions in seed yield from 21.0% to 15.8 and 14.4% as well as 46.2% to 40.8 and 40.1% under WR85% and WR70%, respectively, compared to the farmer common practice (WR100% × SA0.0). WR100% × SA1.0 for iodine value as well as WR100% × SA1.0 and WR100% × SA0.5 for seed oil % were recorded the highest. Application of WR100% × SA1.0 and WR100% × SA0.5 were the effective combinations for ameliorating water use efficiency. In conclusion, involving salicylic acid in irrigation programs of sunflower became a decisive action to save water and alleviate the yield losses resulting from drought stress.

The need for extend the urban horticulture to cover the food security demands, to mitigate CO2 emissions and avoid the extreme heat waves drive this study to investigate the ability of using soilless culture systems, vermicomposting technology and net cover in producing vegetables in urban area in summer season. The aim of this study was to determine the effect of different vermicompost rates mixed with the standard substrate peat moss: perlite (perlite: peat moss: vermicompost (45:45:10) (Mix.10%), perlite: peat moss: vermicompost (40:40:20) (Mix.20%), perlite: peat moss: vermicompost (35:35:30) (Mix.30%) and perlite: peat moss (50:50 V/V) (Control) under three microclimate conditions (plants covered with black net, white net and without cover) on vegetative growth and yield of sweet pepper (Capsicum annuum L. cv. Reda) grown in pots culture during summer seasons of 2012 and 2013 at the Central Laboratory for Agricultural Climate, Agricultural Research Center, Dokki, Giza Governorate. Physical and chemical properties of substrates, vegetative growth and yield characteristics, agrometerological data and mineral contents were determined. The obtained data indicated that vermicomposting could contribute in mitigate CO2 emission, save the essential nutrients and energy via recycling the urban organic wastes to vermicompost. The physical and chemical properties were affected by vermicompost. The best vegetative growth and yield of sweet pepper were given by (Mix.20%) vermicompost mixture followed by (Mix.10%) and (Mix.30%) vermicompost mixture. There were also significant differences between cover net treatments in affecting vegetative growth and yield of pepper, the white net was superior for producing pepper during the summer season; while the black net gave the lowest plant growth and yield. The best treatment was (Mix.20%) vermicompost mixture with white net cover, while the lowest vegetative growth and yield were obtained by (Control) vermicompost mixture with black cover net during the two tested seasons. These results suggested that vermicomposting and green roof can be used in urban area for producing food instead of incineration the urban organic wastes or imported food from rural area and using white cover net to improve the pepper growth and productivity during summer season.

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