No abstract

The use of yeast as a bio-fertilizer in agriculture has taken a considerable attention because of their bioactivity and safety for human and the environment. The current study aimed to evaluate the effect of potassium fertilization and two yeast strains on maize productivity grown on salt affected soil in Dakahlia Governorate to find out their beneficial effect as biofertilizer. Two years field experiment were conducted to investigate the effect of potassium application levels (0, 30. 40 and 50 kg K/fed.) combined with or without Saccharomyces cerevisiae or Rhodotorula mucilaginosa on the maize yields, potassium use efficiency, NPK uptake and soil fertility after harvest. In addition, total microbial and yeast counts as well as dehydrogenase activity after 50 and 80 days from planting were studied. The results showed that application of potassium with yeast significantly increased maize grain and stalks yield, 1000-grain weight and weight of ear/plant. The application of potassium enhanced K % in maize stalk and grain and decreased Na %, as well as markedly raised the maize salt tolerance via increasing the K/Na ratio, especially with the highest rate of potassium fertilization. Potassium use efficiency and potassium uptake were markedly increased with the application of potassium combined with yeast. The highest K-utilization rate 84.93 % was recorded with the treatment consists of 30 kg K/fed + Rhodotorula mucilaginosa. Potassium fertilization positively affects the nitrogen and phosphorus uptake in both studied seasons. Soil salinity and fertility were slightly increased with the application of potassium fertilizers. The highest values of total microbial and yeast counts as well as the dehydrogenase activity were observed with the low levels of K fertilizer associated with Rhodotorula mucilaginosa. So it could be recommended to apply the low levels of potassium together with the yeast strains as a biofertilizer to overcome the salt stress of maize plants.

A field study was conducted during winter season of 2015/2016 at saline soil of Sahl El-Tina, North Sinai Governorate, Egypt, to study the effect of agricultural practices (raised bed system, nitrogen fertilizer rates and seed soaking in concentrations of cobalt solution) whether alone or combined with both on improving the fertility of saline soil and its productivity for faba bean (Vicia faba L. cv. Nobaria 1). Results declared that, the decreasing in soil salinity values (EC) was more clearly in the raised bed shoulder than furrow ridge with increasing the number of irrigations. All growth parameters and yield component were increased to highest percentage at using the raised bed compared to furrow row system. Also, each of seed and straw yield (kg fed -1 ) were increased significantly with gradually increasing the levels of N application up to 100 % combined with 12 mg L -1 of cobalt, but with increasing the concentration in soaking solution up to 18 mg Co L -1 gave negative significantly effect on all the growth parameters studied. Macronutrients contents in faba bean plants were significantly increased with raised bed system, they reached to 34.3, 36.7 and 37.9 % for N, P and K, respectively compared to furrow row system. Also, they were increased with increasing each of N application rates combined with Co concentration (12 mg L -1 ) then decreased with the highest concentration of Co (18 mg L -1 ). The residual available N in soil rhizospher was significantly increased at using all agricultural practices as individual factors. In contrast, there are insignificantly effects of these practices on P and K available contents in soil rhizosphere. Cobalt concentration in seed soaking solution has no effect on increasing its content in plant or soil.

Contamination by polycyclic aromatic hydrocarbons (PAH) and heavy metals poses a major threat to Avicennia marina (Forsk.) Vierh.Mangrove plants grown naturally at the Egyptian Red Sea Coast. Also, microbial determination in A. marina habitats is very essential. Samples of water, rhizosediment, sediment and plant parts (shoots & pneumatophores) were collected from three sites in the habitat of A. marina. These sites are: 17 km south of Safaga, Qulaan and Ras-Mohamed. Sediment contents of Cu, Zn, Ni, Mn, Cr and Cd in all sites were lower than sediment quality guidelines (SQG). No microbial pollution was detected in water samples. The average contents of detected hydrocarbons in plant tissues followed the sequence of: Dibutyl Phthalate (1.103) > Diethyl Phthalate (1.02) >Bis (2-Ethylhexyl) phthalate (0.89) > Pyrene (0.394) > Phenanthrene (0.149) > Isophorone (0.098) µg /Kg. In addition, the stimulatory effects of these plants roots to microbial activity in all areas were studied.

A field experiment was carried out at Batra village-Talkha district Dakahlia Governorate during two successive summer growing seasons 2010 and 2011 to study the effect of two surface irrigation systems (furrow and bed furrow irrigation systems) and four rates of NPK (0-0-0, 60-6.5-20, 90-10-30 and 120-13-40 kg N-P-K/fed, respectively) and their combinations on maize (c.v. single hybrid 30-K-8) yield, yield components, chemical composition, fertilization efficiency, soil fertility and some water relations. The most important results could be summarized as follows. Maize grain and stalk yields were insignificantly affected by irrigation systems in both seasons, but 1000-grain weight was significant. Addition of NPK levels significantly increased grain yield, stalk yield and 1000-grain weight. Interaction between irrigation systems and NPK levels increased grain and stalk yields, insignificantly. N % in stalk and grain was significantly affected by irrigation systems, but P % and K % were insignificantly affected. Addition NPK levels significantly increased N, P and K % in maize stalk and grain. Also, interaction between irrigation systems and NPK levels increased N, P and K concentrations in maize. The values of nitrogen use efficiency (NUE), phosphor use efficiency (PUE) and potassium use efficiency (KUE), were higher with furrow irrigation technique than bed furrow irrigation in two seasons. Also, addition of NPK levels increased NUE, PUE and KUE, respectively compared with control (zero level). The addition of NPK at 90-10-30 kg N-P-K/fed, respectively produced the highest values of NUE, PUE and KUE. Soil fertility were affected by irrigation techniques and NPK levels, where available N in soil increased insignificantly, but available P and K significantly increased with irrigation systems in both seasons. Application different levels of NPK increased significantly the availability of N, P, and K in soil. The average values of soil salinity were increased significantly with bed furrow irrigation methods and NPK levels as well as their interactions. The highest mean value of field water use efficiency in the two seasons (1.34 and 1.43 kg grain/m 3 , respectively) was recorded with 120, 13 and 40 kg NPK/fed under bed furrow irrigation system.