Grapevine (Vitis vinifera L.) quality and growth are affected by the foliar fertilization. Algae extract, glutamic acid, and vitamin B are known as foliar fertilizer but there is little information available about the best combinations of these materials for grapevine. Here, 2-year field study in a randomized complete block design (RCBD) were conducted to study the influence of foliar applications of vitamin B, glutamic acid, and algae (Amphora ovalis) extract on Thompson Seedless grapevines (Vitis vinifera L.) growth and yield. The growth, yield, and quality of grapevine were affected significantly (P < 0.05) by the different treatments. The foliar application of vitamin B, glutamic acid, and algae increased the pruning wood, total chlorophyll, leaf area, and fruit yield compared with the control. In addition, these treatments induced an increase in the concentrations of N, P, and K. The berries quality characteristics of the sprayed vines were significantly better than non-treated ones. Based on the obtained results, the foliar application of glutamic acid, vitamin B complex, and algae besides of their combinations has positive effects on the growth of grapevine plants and berry quality.

Little is known about the response of pomegranate to the foliar application with nutrients and gibberellic acid. A randomized complete block design (RCBD) experiment was conducted on 40-years old Manfalouty pomegranate trees grown on Upper Egypt. The study aims to investigate the effect of foliar application with gibberellic acid (GA 3 ), potassium silicate (PS), zinc sulphate (ZS) and fetrilon compi (FC) which is a mixture of micronutrients on fruiting of pomegranate trees. All the tested treatments significantly (P< 0.05) improved the yield and fruit quality and reduced the fruit cracking percentage. GA 3 and FC spraying induced a 15 and 11% increase in the fruit yield and minimized the cracking percentage by 47 and 61% compared to the control treatment, respectively. It is recommended to spray Manfalouty pomegranate trees with micronutrients, potassium silicate, or zinc sulphate twice at mid of June and August to enhance the pomegranate yield and quality.

Arid degraded soils have a coarse texture and poor organic matter content, which reduces the activity of microorganisms and soil enzymes, and thus the soil quality, plant yield and quality decrease. Potassium solubilizing bacteria (KSB) have been suggested to increase the activity of soil enzymes and increase the release of potassium from natural K-feldspar in the arid degraded soil, and thus potentially reduce the rates of the application of chemical fertilizers. Field studies were conducted for three successive growing seasons in an organic farming system to investigate the effects of K-feldspar and KSB (Bacillus cereus) on K release, soil fertility, and fruit yield of mango plants (Mangifera indica L.). The maximum growth of mango plants was found in the treatments inoculated with KSB. KSB increased soil available N, P, K, and the activity of dehydrogenase and alkaline phosphatase enzymes by 10, 7, 18, 54, and 52%, respectively. KSB increased the fruit yield of mango by 23, 27, and 23% in the first, second, and third growing seasons, respectively. The partial (up to 50%) substitution of chemical K-fertilizer with K-feldspar gave fruit yield and quality very close to that fertilized with the full chemical K-fertilizer. The release rate of K (over all the treatments) varied between 0.18 and 0.64 mg kg−1 of soil per day. KSB significantly increased the K release rate. The application of chemical K-fertilizer gave the highest K release, while substitution with K-feldspar reduced the release of K. Natural K-feldspar contains 8.2% K but is poorly soluble when applied alone. KSB increased the soil quality parameters and enhanced the growth and quality of mango fruit. The fruit yield of mango, under KSB inoculation and fertilization with different K sources, ranged between 9.14 to 17.14 t ha−1. The replacement of 50% of chemical K-fertilizer with natural K-feldspar caused a decrease in the fruit yield by 17, 8, and 2.7% in the first, second, and third years, respectively. The substitution of chemical K-fertilizer with K-feldspar up to 50% with KSB is a good strategy to reduce the excessive use of chemical K-fertilizer. B. cereus and natural K-feldspar have the potential to improve soil health and mango plant productivity in low fertile arid soils.

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