This research study was carried out in the open field during the two successive seasons of 2012/2013 and 2013/2014. The aim of this investigation was to study the response of pot marigold (Calendula officinalis L.) to different application methods and concentrations of seaweed extracts applied as a commercial compound. Seven treatments were initiated, i.e. three concentrations of seaweed extracts (500, 1000, 1500) were used either as foliar spray or as soil drench in addition to the control treatment (tap water). Results indicated that foliar spray with 1500 ppm of seaweed extract increased significantly plant height, number of flowers per plant and vase life in the two tested seasons. However, foliar spray with the lowest concentration of seaweed extract (500 ppm) resulted in significant increments in flower stalk length, flower diameter and carbohydrates content. Moreover, the same concentration showed significant increases in total carotenoids, nitrogen, and phosphorus percentage when used as soil drench in the two tested seasons.

Quinoa (Chenopodium quinoa Willd.) has gained increased a worldwide attention since 1970s when it has been revived as a new food crop, due to the attractive nutritive value and potential health benefits as well as to its exceptional tolerance to several environmental stresses. It is considered as a new non-traditional leafy vegetable crop newly introduced to Egypt. Nitrogen requirements for quinoa plants are not clarified yet and the numbers of studies is still quite limited. The present study was conducted to evaluate the effect of nitrogen sources as ammonium sulfate 20.6% or calcium nitrate 15.5% used at rates of 40, 60 or 80 kg N/feddan on leaf chemical compositions and yield of two quinoa cultivars of Cica and Hualhuas harvested after 40 days from sowing date. A field experiment was carried out at the Experimental Farm of the Horticulture Dept., the Faculty of Agriculture, Ain Shams University, Shoubra El-Kheima, Cairo, Egypt, during the two winter seasons of 2015 and 2016. The treatments were laid out in a split plot design, with three replicates. The obtained results revealed that Cica cultivar was superior to Hualhuas concerning all measured chemical parameters of leaves and leaf yield during both seasons, except for leaf contents of chlorophyll a, b and total chlorophyll, ash, fats, Ca and Fe, where Hualhuas cultivar was superior to Cica in these parameters. However, no significant differences were detected between both cultivars regarding leaf carbohydrates content in both seasons. Re garding nitrogen rates and sources, quinoa plants received 80 kg N/feddan as calcium nitrate gave the highest significant values of carotenoids, nitrate, proteins, ash, N, K and Fe contents in both seasons of the study. Whereas, nitrogen treatment of 80 kg N/feddan from ammonium sulfate gave the highest values of leaf contents of Ca and leaf yield in both seasons. Nitrogen treatment of 60 kg N/feddan from calcium nitrate showed the highest significant values of chlorophyll a, b and total chlorophyll contents during both seasons. No significant differences were realized among all nitrogen treatments (rates and sources) on P content in both seasons. In relation to the interaction effect, the results clearly revealed that leaves of Cica plants received 80 kg N/feddan either from ammonium sulfate or calcium nitrate recorded significant increases in carotenoids, nitrate, proteins, ash, N, P, K and Na contents as well as yield without significant differences between them. On the other hand, the best values of chlorophyll a, b, total chlorophyll in both seasons were attained when Hualhuas plants received 60 kg N/feddan from calcium nitrate. Moreover, there were no significant differences noticed among nitrogen treatments applied to Cica plants in both seasons on Na. Furthermore, the best values of Zn content were obtained when Cica plants treated with 40 kg N/feddan from ammonium sulfate or 60 kg N/feddan from calcium nitrate without significant differences between them in both seasons of the study.  Given the experimental conditions of this study, it is concluded that Cica plants received 80 kg N/feddan either from ammonium sulfate or calcium nitrate gave the highest yield of leaves with acceptable quality attributes.

Two trials were carried out at the Experimental Station farm of Desert Research Center, Teggzerty from Siwa Oasis, Matroh Governorate during the two summer seasons, 2015 and 2016. Trials were performed to study response of two maize hybrids.(Single hybrid 131 and Triple hybrid 329) to organic manure (OM) levels (15 and 30 m3/fed.) and five combinations between mineral and nano nitrogen (N) fertilizers: 1)100% mineral N from the recommended dose (120 kg N/fed.), 2)75% mineral + 25% nano N fertilizers, 3)50% mineral + 50% nano N fertilizers, 4)25% mineral + 75% nano N fertilizers, 5)100% nano N as the recommended rate (500 ppm as foliar application). Mineral N rates were added in three equal doses, with foliar application by nano N rates, after 30, 45 and 60 days from sowing. Treatments, included twenty treatments, was laid out in a splilt-split plot design, with three replicates, OM levels were arranged in the main plots, maize cvs. were allocated in the sub plots, and mineral nano N fertilizer treatments were assigned in the sub-sub plots. At harvest the following characters were recorded, plant height (cm), number of rows/ear, ear length (cm), ear diameter (cm), number of grains/row, 100-grain weight (g), ear weight (ton/fed), grain, straw and biological yields (ton/ fed), shelling (%) and harvest index(%). Results indicated that increasing OM levels significantly increased ear length harvest index and protein content (%), in the 2nd season only, triple hybrid gave the maximum values of all pa rameters, except no. of rows/ear and harvest index, in the 1st season, and 100-grain weight and carbohydrate (%), in both seasons, which had no significant difference with single hybrid in the most cases. Concerning with the effect of mineral and nano N, all parameters, except carbohydrate (%), were increased with increasing mineral N (%) and/or with decreasing nano N (%). Fertilized maize crop by mineral N at 100% or 75% plus 25% nano N fertilizer gave the maximum values of plant ht., no. of rows/ear, ear length and diameter, no. of grains/row, 100-grain wt.,ear weight, grain, straw and biological yields, shelling (%), protein (%), protein yield and harvest index in both seasons. However, fertilized maize crop by nano N at 100% produced the highest value of carbohydrate content (%) in two seasons. Results suggested that selected triple maize hybrid cv. (329), at 30 m3 OM, with 100% mineral N (120 kg N/fed.) or with 75% mineral N (90 kg N/fed.) plus 25% nano N (125 ppm as foliar application) fertilizers could be utilized for attaining the maximal improvement in farmer income by increasing the maize yield under saline conditions at Siwa Oasis, Egypt.

This study was carried out during three successive seasons of 2010/2011, 2011/2012 and 2012/2013 in a private orchard at 76 km Cairo, Alex. Desert road  to investigate the effect of nitrogen and potassium fertilization treatments and shading with white net on yield, and fruit quality of three-years-old mango (Mangifica indica L.) cv. Keitt grafted on sucary seedling rootstocks planted at 2.5×2.5 meters apart grown in sandy soil under drip irrigation system with wells water .This experiment included nine treatments of fertilization: T1= N 80+ K2O 80 Kg/Fed., T2= N 80+ K2O 100 Kg/Fed., T3= N 100+ K2O 80 Kg/Fed., T4= N 100+ K2O 100 Kg/Fed., T5= N 120+ K2O 80 Kg/Fed., T6= N 120+ K2O 100 Kg/Fed.,T7= N 150+ K2O 80 Kg/Fed., T8= N 150+ K2O 100 Kg/Fed. and control (T9) = N 133+ K2O 90 Kg/Fed.. The results cleared that mango Keitt cv. trees grown under white net shading condition significantly increased yield (kg)/ tree, number of fruit set/ panicle, fruit weight, TSS and ascorbic acid content. Trees supplied with 150 Kg/Fed. nitrogen + 100 Kg/Fed. potassium exhibited the highest yield (kg)/tree, number of fruit set/panicle and  fruit weight under shade . Moreover, the best fruit peel color was achieved with trees received 100 kg/feddan of nitrogen +100 kg/feddan of potassium and grown under screenhouse conditions during the three studied seasons. The higher significant value of acidity and TSS were recorded in trees supplied by 120 units of nitrogen + 100 units of potassium during first and third season. Whereas, the control treatment attained a maximum ascorbic acid content.

Two field trials were conducted at Giza Research Station, with split plot design with three replicates during the two successive summer seasons in 2012 and 2013. The aim of this study was to find out the effect of cotingen for covering seed by four treatments (zero, 7.5, 15 and 22.5 g kg-1 grain) and six nitrogen fertilizer levels (control, 30, 60, 90, 120 and 150 kg fed.-1) on maize yield and yield attributes of single cross 10 cultivar. Stepwise multiple linear regression analysis was used to determine the importance of yield components and to predict the yield under different levels of nitrogen and cotingen rates. Nitrogen levels exhibited significant effect for all studied traits, while cotingen were significant for100-kernels weight; shelling% and grain yield traits only. The interaction between cotingen and Nitrogen was significant for row per ear, shelling% and grain yield. Meanwhile, stepwise linear regression analysis showed that 100-kernels weight, number of kernels per row and shelling% were the most important contributing traits to yield (R2 = 82.11%). The nitrogen rates for maximum yield derived from the four statistical models (linear, logarithmic, quadratic, and exponential) describing the response of yield, using the R2statistic to select a model, which shows how each of the models fits the data. The quadratic model best described the yield responses observed in this study. Further confirms the role of nitrogen and cotingen fertilizers in increasing yield production in maize. The 5th N rate under 3rdcotingen (120 Kg fed-1 + 22.5 and 15g kg-1 grain) produced the highest yield being 34.70 and 34.65 ard. fed-1 over all treatments. This is very close to recommendations. The 4th N (90Kg fed-1) rate under any cotingen level produced higher yield than any nitrogen rate only. Economically, considering optimum N fertilization rate, 105.18 Kg fed-1 nitrogen and 22.5 g kg-1 grain cotingen was the most reasonable level. This is considerably below the current recommendation. Therefore, results confirmed that higher cotingen treatment decreased the optimal nitrogen and increased the yield.

A green house experiment was carried out in two successive seasons on date Palm plantlets (Phoenix dactylifera L. cv. Bartomouda) from 2012 to 2013, to evaluated the effectiveness of different sources of nitrogen fertilizer at four treatments as (T2) 5 g/l ammonium sulfate 20 % (1 g nitrogen), (T3) 3 g/l potassium nitrate 33% (1 g nitrogen) and (T4) 2 g/l urea (46%) with the irrigation water one time/ week.The design of the experiment was randomized complete with three replicates. The results revealed that, plant height cm, leaves numbers, root length cm and numbers, and fresh and dry weights of leaves and roots were increasing highly significantly with 3 g/l of potassium nitrate graduated by 2 g/l urea and 5 g/l ammonium sulfate respectively at both seasons. Chlorophyll a, b and carotenoids contents showed significant rising with 3 g/l potassium nitrate. Greatest significant contents of indole and proline were obtained under T3 for two seasons. Leaves nitrogen content N was increased by 2 g/l urea in the two seasons; on the other hand, root nitrogen content was increased with treatment 3 g/l potassium nitrate, sequenced by T2 and T4 treatments. Leaves and roots phosphorus P content significantly raising under 3g/l potassium nitrate and 5 g/l ammonium sulfate for two seasons. In the presence of 5 g/l ammonium sulfate and 3 g/l potassium nitrate leaves and root potassium content K were largest at two seasons respectively. This research shows that the nitrogen formula as potassium nitrate > ammonium sulfate > urea were recommended to highly increasing growth of date palm plantlets in the green house.

From an eco–economic perspective, the efficient use of nitrogen is becoming incrementally worthwhile in crop management. Therefore, growth, yield and seed yield response index of three sesame varieties (Shandwel–1, Giza–32 and Sohag–1) as affected by four N rates (0, 72, 108 and 144 kg N ha−1) were investigated during two seasons of 2013 and 2014. The study illustrated that Sohag–1 was the superior variety for achieving SPAD value and seed yield ha−1. Sesame plants can be fertilized with N at a rate of 108 kg ha−1 being recorded higher seed yield ha−1. Integration between proper variety as a genetic factor with the appropriate N rate applied as an environmental one, i.e. Sohag–1 x 108 kg N ha−1 (or Sohag–1 x 144 kg N ha−1) considered a marked practice for gaining high sesame seed yield as an economic product. Being Sohag–1 exhibited less reduction in yield under low N rate and highly response with high N applied it belongs to ER group.

The potato plants (Solanum tuberosum L.) vs. valor were exposed to different levels of nitrogen fertilizer (60, 100, 140, 180 kg N/feddan (4200 m2)) and in-row plant spacing (12.5, 25 and 50 cm) for maximizing the yield production to match food security needs under climate change impacts on Delta region,  Egypt. The experiment was carried out during two growing seasons (2010/2011 and 2011/2012) in split plot design at El-Bossily Farm, Agricultural Research Center, El-Behira Governorate, Egypt. The vegetative growth characteristics and yield parameters were measured. The result of this study verified that increasing nitrogen level up to 180 kg N/feddan significantly increased the vegetative growth, total and marketable yields than the other N treatments. The in-row plant spacing 50 cm was significantly increased vegetative growth and yield (kg/plant), but the total yield (kg/m2) had different trend. The highest total yield /m2 was obtained by 12.5 cm treatment. The interaction effect of 180 kg/feddan of N and 12.5cm in-row plant spacing were increased the total tuber yield (kg/m2) significantly. In contrary, the best marketable yield (tubers > 35 mm) /m2 was obtained by 25 and 50 cm in-row plants.  This study was concluded that the best agronomic practices for potato production obtained by application 180 kg N/feddan of with in-row plant spacing 25 cm treatment. The economical consideration of the different treatments showed that the best total net income was obtained by 180 kg/feddan N with 50 cm in-row plant spacing.

This study was conducted in a sandy soil at Ali Mubarak Village Research Farm, South Tahrir Horticulture Research Station, Behaira Gover-norate, during the two successive seasons of 2002/2003 and 2003/2004 on sweet corn Jubilee hybrid. The study aimed to determine the best treatments of nitrogen fertigation level and chelat-ed calcium foliar application on the productivity and quality of sweet corn. The obtained results indicated that increasing nitrogen fertigation level (100, 120, 140 to 160) kg N/fed. and (or) chelated calcium (12% Ca++) concentration (500 and 1000 ppm Ca EDTA) led to increasing the vegetative growth (leaf area, plant height, fresh and dry weight), chemical composition (total chlorophyll, nitrogen, phosphorus, potassium and calcium in leaves) and yield characters (ear length, ear diame-ter, weight of 1000 seed, unhusked ear, husked ear and total yield) The promising treatment was 160 kg N/Fed. combined with 1000 ppm Ca EDTA under similar prevailing conditions of the present studying in a sandy soil