Rasha S. Abdel-Hak

The present investigation was conducted over two consecutive seasons on 15-year-old Barhee date palms (Phoenix dactylifera L.) cultivated in an exclusive orchard 63 kilometers along the Cairo-Alexandria Desert Road in sandy soil under a drip irrigation system. For three times, bunches of the tested palms were misted with GA3, boric acid, or active dry yeast: once a day before pollination, once a month after fruit set, and once a month before harvest. GA3 was sprayed at the previous dates with 50, 100, and 50 ppm, respectively, while boric acid was sprayed at the same dates with 2000, 1500, and 1000 ppm. Similarly, active dry yeast was sprayed at the same dates with 250, 500, and 250 ppm. The investigated treatments were compared with untreated palms. The findings indicate that all spraying treatments improved fruit properties, both chemical and physical, and boosted fruit set and yield compared to the control. In general, the most effective treatment to increase fruit set, production, and the physical and chemical properties in both seasons was the procedure of spraying inflorescences with active dry yeast three times (250, 500, and 250 ppm).

The present work aimed to evaluate green-nano manganese produced at the Microbial Biotechnology Department, National Research Centre, Egypt, and assess its impact on the growth, yield, and fruit properties of grapevines. To this end, two experiments were conducted. The first was microbiological, where several incorporation strategies were utilized to enrich the yeast with manganese, as follows: (1) manganese was added to the liquid medium (non-growth phase), and (2) manganese was added after 24 h of incubation (growth phase). The results showed that the non-growth phase had a reduced possibility of medium contamination. The manganese concentration in the yeast cells was increased due to manganese sulfate in the medium. The manganese incorporation in yeast cells was 99.93% (1.205 × 105) higher than that of the medium at 0.0195 g/L of manganese. Although the concentration of manganese in the medium raised the optical density (OD) of the yeast cell biomass, manganese sulfate had no passive influence on it. The second experiment was horticultural, where Flame Seedless grapevines were sprayed with frozen and active fresh yeast enriched with manganese that resulted from the microbiological experiment. Grapevines were sprayed twice a year at 10 or 20 cm³/L, and the results were compared with those for the mineral and chelate forms. The results demonstrated that yeast extracts in both forms showed positive effects on grapevine. The most effective treatment with regard to growth, yield, and fruit properties was frozen yeast enriched with manganese at 20 cm³/L, which yielded 10.14 and 12.6 kg/vine, compared with the control, which recorded 3.7 and 5.6 kg/vine in the two seasons, respectively.

Two experiments were conducted to develop a Nano green manganese and assess its effect on grapevines. The first experiment was microbiological, where several incorporation strategies were utilized to enrich the yeast with manganese, as follows: (1) adding manganese to the liquid medium (growth phase), (2) adding after 24 h of incubation (non-growth phase). As the results, growth phase reduced the possibility of medium contamination. Manganese concentration in the yeast cells was increased as that of manganese sulphate in the medium. Manganese incorporation in yeast cells was 99.93% higher than that of the medium at 0.0195 g/l of manganese. Although the concentration of manganese in the medium raised the OD of yeast cell biomass, manganese sulphate had no passive influence on it. The second experiment was horticultural, done on Flame Seedless grapevines, since both active fresh and frozen yeast enriched with manganese resulted from the first experiment were sprayed twice a year at 10 or 20 cm3/l comparing with manganese sulphate, and manganese chelate. The results demonstrated that yeast extracts in both forms increased the yield and improved fruit properties. The most effective treatment on vegetative growth, yield and fruit properties was the frozen yeast enriched with manganese at 20 cm3/l.