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The present work evaluated the effect of soil (S) and foliage (F) applied potassium on the growth, yield, and quality of potato plants. Potassium was added in soil at the recommended rate for all the treatments combining mineral fertilizers with K-feldspar and biofertilizers, while foliar spraying included the application of potassium citrate (PC), potassium silicate (PS), and monopotassium phosphate (MP). The obtained results showed that plant height was highest following treatment with 100% mineral potassium fertilizer under the foliar application of MP, while the content of P, K, and total carbohydrates in leaves also increased with the same fertilization treatment. On the other hand, the highest values for number of stems and fresh and dry weight per plant, as well as the highest nitrogen content in leaves, were obtained after the addition of mineral potassium fertilizer and the foliar spraying of PC, regardless of the growing season. Yield parameters were positively affected by the combination of mineral potassium fertilizers (100% or 80% K2SO4 + 20% K-feldspar + biofertilizer) and the foliar spraying of MP, while the total nitrogen, protein, amino acids, potassium, phosphorus, and starch content of tubers were positively affected by the same mineral fertilizer treatments combined with foliar spraying of MP or CP. In conclusion, the application of mineral potassium fertilizer with foliar spraying of MP or CP increased most of the plant growth- and tuber chemical composition-related parameters. These results highlight the importance of potassium fertilizer regimes for achieving high tuber yields and improving the quality of tubers in a sustainable and cost-effective manner.

Strawberries are rich in antioxidants and plant components to enhance cardiac health and regulate blood sugar. This experiment investigates the effects of N fertilization and foliar spraying with calcium (Ca) and boron (B) on growth, chemical composition of plant foliage, fruit yield, and quality of strawberry plants (Fragaria x ananassa Duch. cv. Fortuna). This experiment includes 12 treatments from the combination between four N fertilizers treatments (combinations of mineral and organic fertilizers) and three foliar spraying treatments with Ca+B at 2 and 4 mL/L in addition to the control treatment (spraying with tap water). Results show that the treatment where 50% of the recommended dose of N (50% RDN) was applied with mineral fertilizer + 100% organic N was the most effective one since it induced the highest values of plant height, number of crowns per plant, number of leaves per plant, fresh and dry weight per plant, especially when combined with the foliar application of Ca+B at the highest tested rate (4 mL/L). The highest values of N, P, K, Ca, B, and total carbohydrate contents were also scored for the combination of 50% RDN + 100% organic N and the foliar spraying with Ca+B at 4 mL/L in both growing seasons. In addition, the highest values of fruit yield per plant and per hectare, exportable fruit yield/ha, fruit firmness, fruit TSS, Vitamin C, total sugars, and anthocyanin, as well as the lowest values of total acidity were recorded for the combined treatment of 50% RDN + 100% organic and Ca+B at the highest rate (4 mL/L). The highest recorded value of length, diameter, and weight of fruit were scored by fertilizing strawberry plants with the recommended dose of mineral N (100% RDN) and spraying with Ca+B at the highest rate in both growing seasons. In conclusion, it could be suggested that fertilization of strawberry plants with half the recommended dose with mineral N fertilizer + 100% organic fertilizer and foliar spraying with Ca+B at 4 mL/L increases plant growth and improve yield parameters and fruit quality of the strawberry plants.

This work investigated the effects of potassium mineral fertilizers, combined with biofertilizers (T1–T4 treatments) and the foliar spraying of seaweed extract (at 1 g/L, 2 g/L, and 3 g/L) on the vegetative growth characters, chemical constituents of foliage, and the yield and quality parameters of globe artichoke. The maximum height, and the fresh and dry weight of the leaves, was recorded in plants that received only soil with added potassium (T1 treatment) and sprayed with seaweed extract at 3 g/L. Furthermore, the highest number of offshoots per plant was registered in the T2 treatment combined with seaweed extract (3 g/L). T1 and T2 treatments resulted in the highest values of leaf N, P, K, and total carbohydrate content when combined with seaweed extract (3 g/L). The highest numbers of early, late, and total heads per plant were obtained for the T1 treatment and seaweed extract (3 g/L). Similarly, most of the head quality parameters were beneficially affected by the T2 treatment and seaweed extract (3 g/L). In conclusion, it is suggested that soil application of mineral potassium fertilizer (75% of RD) combined with biofertilizer (25% of RD) and the foliar spraying of seaweed extracts at 3 g/L, was most beneficial for the yield and quality parameters of globe artichoke plants.

Sweet pepperincludes several vitamins and is regarded as a great source of bioactive nutrients, such as carotenoids and phenolic compounds, for human growth and activities. This work aimed to investigate the effects of the soil addition of growth stimulants, namely, effective microorganisms (EM), compost tea, fulvic acid, and yeast extract, and foliar applications of seaweed extract, on the vegetative growth, enzyme activity, phytohormones content, chemical constituents of plant foliage, fruit yield, and fruit quality of sweet pepper plants (Capsicum annuumL. cv. Zidenka) growing under greenhouse conditions. The results showed that the tallest plant, largest leaf area/plant, and heaviest plant fresh and dry weights were recorded after combining a soil addition of yeast extract and foliar spray with seaweed extracts at 3 g/L in two growing seasons. The highest number of fruit/plant, fruit yield/m2, fruit values of vitamin C (VC), total sugars, total soluble solids (TSS), and carotenoids, along with the highest leaf of cytokines, P, K, Fe, and total carbohydrates values, were obtained using a soil addition of fulvic acid and spray with seaweed extract at 3 g/L in the two seasons of study. These treatments also provided the lowest abscisic acid, peroxidase, and super oxidase dismutase values in the same conditions. Sweet pepper plants supplemented with compost tea and seaweed extract foliar spray at 3 g/L were the most promising for inducing the highest values of fruit fresh and dry weights, fruit length and diameter, and the leavesrichest in N, Zn, and Mn; inversely, it induced the lowest catalase levels in both seasons. The applications of EM, yeast extract, and seaweed extract could be applied for high growth, mineral levels, enzymatic activity, fruit yield, and nutritional value of sweet pepper fruit and minimizing environmental pollution.