Interaction Effects Of Nitrogen Research Articles

Effects of Different Nitrogen and Sulfur Fertilizer Rates on Growth, Yield, Quality and Nutrient Uptake of Onion (Allium cepa L.) at Shewa Robit, North Shewa, Ethiopia

Background: Onion is one of the most important crops widely cultivated throughout the world, including Ethiopia. The production of onion is mainly affected by the inadequate application of inorganic fertilizer types and rates. Objective: A field experiment was conducted to evaluate the effect of nitrogen and sulfur fertilizers on the growth, yield, quality, and nutrient uptake of onion at Shewa Robit in 2018/19 under irrigation. Methods: The experiment consisted of four nitrogen rates (100, 150, 200, and 250 kg N /ha) and five sulfur rates (0, 15, 30, 45, and 60kg S/ha). The treatments were laid out in a factorial arrangement with three replications using randomized complete block design (RCBD). Bombay Red was used as a testing onion variety. Results: The interaction effect of nitrogen and sulfur significantly increased plant height, leaf length, leaf diameter, leaf area index, neck diameter, shoot dry weight, bulb fresh weight and bulb dry weight, percent dry matter content, yield, and quality parameters. The application of 200kg N/ha and 45 kg S/ha resulted in the highest yield (42.6 t ha-1), the average weight of bulb (193.6g), and a marketable bulb (99.8%). The highest N uptake (243.3 kg ha-1) and S uptake (31.9kg ha-1) were obtained by the combined application of 200 kgN/ha and 45kg S/ha. Conclusion: The application of 200 kgN/ha and 45kgS/ha can be recommended for high yield and quality onion production in the study area.

Interaction Effect of Nitrogen and Phosphorus on Curd Yield and Seed Production of Cauliflower

Aims: This study aimed to investigate the interaction effect of nitrogen and phosphorus on curd yield and seed production of cauliflower.
 Study Design: The experiment was laid out at a randomized complete block design with three replications.
 Place and Duration of Study: Research farm of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, from September 2016 to March 2017.
 Methodology: The experiment consisted of two factors comprising three levels of nitrogen (270, 220,170 kg ha-1) and three levels of phosphorus (160,130,100 kg ha-1) with control of each nutrient. There were 10 treatment combinations resulting in 30 unit plots where each plot had two rows of 6 plants. Nitrogen and Phosphorus fertilizer were applied as per treatment in the form of Urea and TSP as a top dressing in two equal splits at the time of transplanting and 15 days after transplanting.
 Results: All the characters related to growth and yield of cauliflower showed significant variation by nitrogen and phosphorus levels at different days after transplanting. Among the different treatment combinations, N270P160 produced maximum plant height (50 cm), leaf area (700 cm2), plant weight (1003 g), curd diameter (18.3 cm), marketable curd weight (601 g) and marketable curd yield (18.5 t) at harvesting compared to control where nitrogen and phosphorus were not used. Moreover, the largest number of leaves (21.3) and curd weight (346 g) was observed by treatment combinations N220P160 at harvesting. For seed production, the highest number of siliqua plant -1 (1461), 1000 seed weight (4 g), seed yield plant-1 (41.1 g) seed yield ha-1 (1.5 t) and germination (97.7%)was also found from N270P160while the maximum number of seeds siliqua-1(20.5) was revealed by N220P160 compared to control treatment. Considering a different point of view, treatment combinations N270P160 can be marked more convenient for cauliflower production than others.
 Conclusion: It is concluded that the combinations of nitrogen (270 kg ha-1) and phosphorus (160 kg ha-1) would be appropriate for curd yield and seed production of cauliflower.

Effect of Nitrogen Fixing Bacteria and Nitrogen Rate on Yield and Growth of Common Bean

To study the effects of nitrogen (N) rate and co-inoculation of nitrogen-fixing bacteria (Rhizobium phaseoli) on common bean, an experiment was performed in Rasht, Iran. Common bean genotype, Guilanian landrace, was planted in a factorial experiment based on a randomized complete block design with three replicates on April, 15th in 2014. The first and second factors were nitrogen rates (0, 30, 60, 90 and 120 kg.ha-1 as urea) and Rhizobium phaseoli (inoculation and un-inoculation), respectively. Nitrogen had significant effect on seed yield and plant height. The effect of Rhizobium phaseoli was significant on seed yield, plant height, pod length, pods per plant, seeds per pod and nitrogen content in leaf. Interaction effects of nitrogen and Rhizobium phaseoli were not significant on any of the traits. Application of 60 kg.ha-1 nitrogen significantly improved seed yield, plant height and number of pods per plant. Nitrogen supply beyond the 60 kg.ha-1 decreased plant height, pods per plant and seed yield. The greatest values of seed yield (1635 kg.ha-1), plant height (30.01 cm), pod length (13.19 cm), number of pods per plant (6.7), number of seeds per pod (4.34) and nitrogen content in leaf (4.12%) was observed in inoculation treatment. The results indicated the inoculation of common bean seeds by Rhizobium phaseoli improved the plant growth, productivity and quality. Therefore, the common bean inoculation with Rhizobium phaseoli is suitable to achieve the yield potential and reduce the adverse effects of environmental and may be recommended due to its advantages in terms of reduced application of nitrogen fertilizer.

Efecto de la interacción del nitrógeno con el potasio sobre la intensidad de la clorofila en el cultivo del banano

This research was carried out at the Experimental Farm Santa Inés of the Faculty of Agricultural Sciences at the Technical University of Machala, with the aim of evaluating the effect of nitrogen interaction with potassium on the intensity of chlorophyll in banana cultivation. In the IC variable the treatments that carried nitrogen (200, 400 and 600 kg ha-1) were observed statistical differences at dose 0 kg ha-1 were observed, different behavior was observed in treatments carrying K doses, where all THE CI and AF variables showed no statistical differentiation between doses 0, 350,700 and 1050 kg ha-1 of K2O. In the evaluation of the AF variable the treatments that carried nitrogen were statistically differentiated at the dose 0 kg ha-1, on the other hand, treatments with doses of 0, 350, 700 and 1050 kg ha-1 of K2O, did not show statistical differentiation. These data were corroborated by an F-test, where treatments that carried nitrogen differed statistically, not so, the K doses and NK interaction for IC and AF, however, the May AF if it had statistical interaction of K and its interaction. The non-application of nitrogen fertilizers negatively influenced both the IC and AF variable, demonstrating that the application of 200 of N and K2O kg ha-1son sufficient for the development of appropriate of these two variables.

Increased Medicinal Contents of Purslane by Nitrogen and Arbuscular Mycorrhiza under Drought Stress

ABSTRACT Worldwide, purslane (Portulaca oleracea L.) is well-known for its fatty acids and antioxidants. To investigate interaction effects of nitrogen and mycorrhiza under water deficit stress on agronomic and medicinal traits of the purslane, a factorial split experiment based on a randomized complete block design with three replications was conducted in a semi-arid region of Iran in 2015 and 2016. The main plots were factorial combination of two irrigation conditions (non-stressed control and stressed condition: irrigation at 70% and 50% of field capacity (FC), respectively) and two treatments, i.e. control and inoculation with arbuscular mycorrhiza fungi (AMF, Rhizophagus irregularis). The subplots consisted of unfertilized control, 100% farmyard manure (8.5 mg FYM ha−1, sheep manure (50%) and chicken manure (50%)), 100% N (120 kg urea ha−1), 75% FYM and 25% urea, 50% FYM and 50% urea, 25% FYM and 75% urea. In the first and second years, drought stress reduced AMF colonization (by 30.3% and 15.3%), phosphorus content (by 5.8% and 7.7%), nitrogen content (by 11.91% and 8.63%), total antioxidant capacity (by 16.7% and 14%), and biomass matter (by 21.1% and 17%) in purslane, respectively, while contributing to the production of malondialdehyde, total flavonoid, saturated and unsaturated fatty acids. AMF treatment increased the biomass weight, total antioxidant activity, and unsaturated fatty acid content of leaf in purslane. Application of nitrogen fertilizers enhanced phosphorus and nitrogen uptakes, biomass weight, flavonoid content, total antioxidant capacity, and fatty acid contents of the leaf under both irrigation conditions, while lowering leaf malondialdehyde content.

Interaction effects of nitrogen and phosphorus fertilizer on nitrogen mineralization of wheat residues in a calcareous soil

Because of the high pH of the soil in semiarid regions, phosphorus adsorption is unfavorable. So, considerable amounts of phosphorus fertilizers are used annually, where this fertilizer may affect the plant residues' decomposition. To examine the interaction effects of nitrogen and phosphorus on nitrogen mineralization in calcareous soil, a factorial experiment was performed in a completely randomized design with three replications. The first factor consisted of various C:N ratios (20, 40, and 60 or three levels of nitrogen N1:0, N2:11, and N3:43 kg N ha−1, respectively) and the second factor consisted of various C:P ratios (87, 174, and 260 or three levels of phosphorus P1:0, P2:12, and P3:45 kg P ha−1, respectively), under incubation conditions. The results indicated that the cumulative mineral nitrogen content in all treatments, except for N1P2 and N1P3 treatments, started from a positive amount and remained positive until the end of the incubation period. The highest amount of cumulative mineral nitrogen among treatments was related to N3P1 treatment, while the lowest was associated with N2P3 treatment. Mineralization of nitrogen during 60 d of incubation was the dominant phenomenon, except for the N1P2 and N1P3 treatments which remained in the organic phase. The effect of phosphorus on the cumulative mineralization of nitrogen was significant. With increasing the amount of phosphorus, the total inorganic nitrogen diminished. Nitrogen release begins earlier with lower C:N ratios, and therefore the available nitrogen can be released more quickly to the plant. It is generally concluded that, in calcareous soil, the use of nitrogen fertilizer to adjust C:N ratio and to improve the mineralization of wheat residues will be a suitable option.

Effects of Intra-Row Spacing and N Fertilizer Rates on Yield and Yield Components of Tomato ( Lycopersicon Esculentum L.) at Harawe, Eastern Ethiopia

Improper plant spacing and nitrogen fertilizer are among the main factors which constrained productivity of the tomato. Due to this gap the experiment was proposed and conducted in Sofi district, Harari People Regional State, Ethiopia in 2016 and 2017 cropping season to investigate the effect of intra-row spacing and nitrogen fertilizer on yield and yield components of tomato. Experimental treatments were nitrogen rates (0, 39, 69 and 99 kg ha-1) and intra-row spacing (25, 30, 35 and 40cm). A total of 16 treatments were arranged in randomized complete block design with three replication. Melkashola Variety was used for the experiment. The results revealed that there were significant (P<0.05) differences for plant height, number of branches, fruit clusters per plant, number of fruits per plant due to nitrogen application. Increasing nitrogen rate from nil to 69 kg ha-1 increased all these parameters. Average fruit weight and fruit yield were significantly (P<0.05) affected due to the interaction effect of nitrogen and intra-row spacing. The highest fruit weight was recorded at 39 kg N ha-1 and 40cm intra-row spacing while the lowest were at 0 N and 40cm intra-row spacing. The highest fruit yield was recorded at 69 kg ha-1 N and 30cm intra-row spacing while the lowest was at 0 N and 40cm intra-row spacing. In conclusion, the application of 69 kg N ha-1and 30cm intra-row spacing recorded highest fruit yield with highest economic returns (270,330 birr ha-1). Based on fruit yield and economic return, combination of 69 kg N ha-1 and 30cm intra-row spacing was recommended for the study area and similar agro-ecology.

English

An experiment was conducted at Haramaya University, Horticulture Research Field, Haramaya during the period from 13 August, 2010 to 17 January, 2011 to investigate the effect of manure and different levels of nitrogen on yield and yield attributed traits. A local garlic cultivar was used for the study. The treatments consisted of four levels of nitrogen (0, 50,100 and 150 kg/ha) and three levels of goat manure (0, 10 and 20 t/ha). The experiment was laid out as a randomized complete block design (RCBD) in a factorial arrangement and replicated three times. The results revealed that interaction effects of nitrogen and manure significantly (P 0.05) on leaf number. However, the combined application of 50 kg/ha N and 10 t/ha manure significantly (P<0.05) increased mean fresh bulb weight, mean clove weight, total bulb yield, and harvest index. Maximum yield (27.8 t/ha) was recorded at the combined application of 50 kg/ ha N and 10 t/ha manure. It can, thus, be concluded that for short term garlic production, smallholder farmers could not only get optimum yield of garlic from the combined application of 50 kg/ha N plus 10 t manure/ha but also could save considerably on inorganic fertilizers that can be used for increasing yield of other crops to enhance food security and income. Key words: Allium sativum, garlic, goat manure, nitrogen, yield.

Interaction effect of nitrogen, phosphorus, and zinc fertilization on growth, yield, and nutrient contents of aromatic rice varieties

Studies on nutrient interactions in aromatic rice are needed for proper understanding of impact of imbalanced use of nutrients in the era of multi and micro-nutrient deficiencies. A pot experiment was conducted during the rainy/wet season (June–October) of 2013 at New Delhi, to study the interaction effects of two levels each of nitrogen (N) (0 and 120 kg ha−1), phosphorus (P; 0 and 25.8 kg ha−1), and zinc (Zn; 0 and 5 kg ha−1) in two aromatic rice (Oryza sativa L.) varieties, viz. Pusa Rice Hybrid 10 and Pusa Basmati 1121. Application of N, P, and Zn resulted in increase of dry matter (0.91, 0.32, and 0.24 g plant−1, respectively) 60 days after sowing (DAS) and grain yield of rice (3.68, 1.67, and 1.17 g plant−1). The increase in yield of rice owing to N application was relatively higher by 0.98, 0.22, and 1.05 g plant−1, respectively, when either P or Zn or both were applied with N than alone application of N, indicating synergetic effect of P and Zn application with N. The higher concentration and uptake of K in grain (0.25% vs 0.10%) and straw (1.32% vs 0.94%) were observed in the treatment received N than no N, though K was applied uniformly in all the treatments. It indicates positive interaction of N and K. The higher uptake of P in grain and straw was observed when P was applied with N and Zn (3.34 and 2.15 mg plant−1), or with N (3.26 and 2.11 mg plant−1) signifying positive effect of N on P uptake in rice.

Studies on Effect of Nitrogen Fertilization and Foliar Feeding of Calcium and Bio Stimulants on the Growth, Yield and Post- Harvest Quality of Garlic II. Effects of Nitrogen, Chitosan and Storage Durations on Post- Harvest Quality of Garlic

xandria University in Abies, Alexandria, Egypt, during the winter and summer season of 2017, respectively. Thisstudy aimes to evaluate the effect of nitrogenrates (0, 50, 100 and 150 Kg Nfed-1) and chitosan (0, 1, 2 and 3 mll-1)and their interaction effects on postharvest quality of garlic plants. The results showed that the percentage of weight lossand chemical composition of garlic (T.S.S , dry matter and total carbohydrates) were significantly increased as N-levelincreased from 0 up to 150 Kg N fed-1 as well as chitosan concentrations was increased from 0 up to 3 ml/ l. The resultsindicated also that there were significant interaction effect due to nitrogen levels and chitosan concentrations on allcharacters. The storage durations months had significant effects on weight loss of garlic bulbs. It was observed thatweight loss of garlic bulbs gradually increased with the increase of storage duration up to 4 months. All minerals (N,P,K)and Protein contents of garlic bulbs were significant increased by the application of nitrogen fertilization up to 150 Kg Nfed-1as well as by spraying of chitosan up to 3mll-1. The interaction effects of nitrogen and chitosan on N andprotein contents of garlic bulbs before or after storage were significant, however, there were as no significant effects onP and K contents of garlic bulbs after storage.

Ecological fitness of brown planthopper, Nilaparvata lugens (St\xe5l), to rice nutrient management

IntroductionThe brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), is a notorious insect pest of rice. Nutrient supplementation can alter plant biochemical compositions which may indirectly affect on ecological fitness parameters of its insect pest. However, few findings are available on nutrient-induced ecological fitness of BPH and relationship of BPH fitness parameters with its host rice plant biochemical contents.MethodsWe studied the main and interaction effects of nitrogen (N), phosphorus (P), and potassium (K) inputs on BPH fitness, as measured by the following variables: nymph survival, nymphal duration, adult body weight, and its survival. Brown planthopper fitness parameters were regressed as function of rice plant (Oryza sativa) biochemical composition. A completely randomized design with four replications in a factorial scheme was used considering N, P, and K levels as factors.ResultsNitrogen application to the host rice plants provided greater survival and enhanced body weight of BPH. The nymphal duration was found to decrease with N subsidy that caused shorter generation time of BPH. Nitrogenous compounds N and soluble protein (SP), total free sugar (TFS), and silicon (Si) content in rice plant tissue correlated strongly with all fitness traits of BPH. Nitrogen, SP, and TFS associated positively with BPH survival and body weight, while negatively with nymphal duration. In contrast, Si had negative correlation with BPH survival and body weight, but positive with nymphal duration. Phosphorus supplementation to host plant contributed to increase BPH body weight. Relationships of P with all parameters of BPH were weak except body weight which was highly significant and positive. Interaction between N and P inputs demonstrated significant effect on BPH body weight. Application of K had no significant effect on BPH survival and development. Regression analysis did not detect significant relationship of BPH fitness parameters with plant tissue content of K.ConclusionsThe results suggest that BPH ecological fitness characters were improved after N and P fertilization to rice plants which are associated with biochemical content of rice plant. Therefore, N and P inputs should be used judiciously in rice cultivation to keep BPH ecological fitness potential at minimum level.

Interaction effect of nitrogen and vermicompost in the presence of herbicide (Clodinafop propargyl) on nitrogen transformation in a sandy soil

A laboratory experiment with three levels of nitrogen (0, 100 and 200 mg kg-1), two levels of vermicompost (0 and 1 % on dry wt. basis) and two levels of herbicide (0 and 60 g a.i. ha-1) was conducted with sandy soil of Hisar to study the interaction of nitrogen and vermicompost in the presence of herbicide (clodinafop propargyl) on nitrogen transformation during 2014. NH4+-N contents increased upto the 14th day in soil and then declined up to 56th day under control. NO3--N content in soil increased significantly throughout the incubation study under control. With con-junctive use of nitrogen along with vermicompost, NH4+-N contents increased significantly in the soil upto 14th day of incubation with an increase from 44.49 to 73.22 mg kg-1 and 64.00 to 102.87 mg kg-1, whereas NO3--N content in soil significantly increased throughout the incubation study over control and the increase was from 13.68 to 101.36 mg kg-1 and 23.19 to 115.48 mg kg-1. However, NH4+-N and NO3--N decreased significantly at all incubation periods with the application of herbicide alone and in presence of nitrogen as well as vermicompost. The study revealed that judi-cious use of N, leads to more availability of N to crop and prevents the environmental pollution. Higher levels of N application may increase the risk of ground water pollution due to more availability of NO3- ion which can be sub-jected to leaching losses. Vermicompost proved to be the important source of nutrients as it has narrow C:N ratio and decompose more quickly than other organic manures such as FYM etc. Among commonly used herbicides, clodinafop propargyl is most commonly used herbicide and may have negative impact on the microbial population and thus may hinder the transformation processes particularly in sandy soils which have low organic matter content and thereby affecting the availability of nutrients to crop and play decisive role in crop yields.

Source and sink indicators for determining nitrogen, plant density and genotype effects on oil and protein contents in sunflower achenes

Given the diversification of oilseed-based products, sunflower is a competitive crop for obtaining high oil and protein concentrations; however, both are subject to genotypic and environmental variability. We analyzed individual and interaction effects of nitrogen (N), plant density (D) and genotype (G) in a 2-year field experiment. A set of “sink” (oil, protein, and hull concentrations and quantities) and “source” (leaf area duration, nitrogen uptake, nitrogen and biomass remobilizations) indicators were measured at harvest in a split-split-plot design with contrasting nitrogen (N+: 150kgha−1; N−: no fertilization), plant density (D1: 3 and D2: 4.5 plants m−2) and genotype (cv. LG5451HO in 2011, cv. Olledy in 2012 and cv. Kerbel in both years) treatments. We found that nitrogen had a significant positive effect on protein concentration and plant density had a positive effect on nitrogen uptake after flowering. Oil concentration was not related to oil weight but was related to plant dry matter at flowering and biomass remobilization. Protein concentration was related to protein weight and nitrogen nutrition index at flowering and to nitrogen uptake and leaf area duration after flowering. Significant interaction effects were identified on sink (N×D, D×G) and source (N×G) indicators in the 2012 experiment, which was only partly explained by differences in initial states at flowering. In this study, the genotype that maximized oil concentration depended on nitrogen and plant density conditions, while the genotype that maximized protein concentration was the same regardless of cropping conditions. We highlight the importance of analyzing effects of determining factors on oil accumulation during grain filling.

Effects of nitrogen treatment and intra-row spacing on the morphological and physiological characteristics in pumpkin (Cucurbita pepo L.)

Pumpkin (&lt;em&gt;Cucurbita pepo&lt;/em&gt; L.) is a medicinal plant recently under common cultivation in Iran. The seeds and its products are used in the treatment of some diseases. Due to the lack of information about the intra-row spacing and nutritional demands of the plant a factorial experiment with Randomized Complete Block Design with three replications was planned in Azarbaijan Shahid Madani University Research Field in 2013. The treatments were 5 levels of Urea fertilizer (0, 50, 100, 150, 200 kg/ha nitrogen), and intra-row spacing in 3 levels (30, 60 and 90 cm). The result showed that interaction effects of intra-row spacing and nitrogen treatment had significant effect on some morphological traits such as plant height, number of auxiliary branches and leaf number per plant. Application of 200 kg/ha nitrogen increased the plant height, the number for auxiliary branches and leaves as well as the leaves dry mass, mainly due to the prolonged vegetative growth period and delayed flowering and fruiting. 150 kg/ha nitrogen combined with 60 cm intra-row spacing hold the highest number of female flowers, fruit number and intact fruit number and fruit fresh weight, and the highest dry weight of the intact seeds. The results for some physiological traits showed that interaction effects of nitrogen and intra-row spacing had significant effects on chlorophyll b at the late stages of flowering period and the contents for chlorophyll a and carotenoids were significant at the end of growing season. The highest oil content was recorded in 150 kg/ha nitrogen and 60 cm intra-row spacing. Based on results obtained, 150 kg/ha nitrogen and 60 cm intra-row spacing were the best regime for the production of this plant.

Role of silica and nitrogen interaction in submergence tolerance of rice

Submergence is an intensifying problem in major rice producing areas, when intolerant cultivars are submerged, they show a number of morpho-physiological changes such as elongation and chlorosis which is markedly developed after desubmergence probably due to oxidative damage. We studied the effects of submergence on survival, photosynthesis, nonstructural carbohydrate content, enzymatic activities, growth and yield of Sub1 and non-Sub1 cultivars. The interaction effect of nitrogen (N) and silica (Si) application was also examined for the submergence tolerance in rice. The photosynthetic rate, survival, growth of all the cultivars decreased during submergence but to a greater extent in IR64 and Swarna. After desubmergence, both the type of cultivars experienced oxidative damage, however, the oxidation of lipids was maintain at lower levels in Sub1 cultivars and anti-oxidants activities was increased more than intolerant cultivars. Application of basal Si was beneficial whereas, pre- and post-submergence Si spray was detrimental in relation to submergence tolerance. Basal Si resulted in significantly reduced elongation, lodging, leaf senescence, and chlorosis; when combined with post-flood N application either as broadcasting or spray, it led to significantly highest survival, photosynthesis, anti-oxidant activity and ultimately yields. Interaction of basal Si and post-flood N spray was the most promising method of nutrient application which not only resisted the damage during submergence but also enhanced the survival, growth after recovery in terms of number of green leaves emergence, leaf area and photosynthetic rate leading to significantly higher yield. The findings of the investigation propounds that a simple alteration in the time and method of nutrient application can significantly contribute to higher survival, crop establishment and yield in flash-flood prone areas.

Effect of Spacing and Nitrogen Fertilizer on the Yield and Yield Component of Shallot (Allium ascalonium L.)

This research was conducted to study the interaction effect of different rate of nitrogen fertilizer and plant spacing on yield and yield components of shallot under Jimma condition, in the experimental field of College of Agriculture and Veterinary Medicine, Jimma University. Local variety of shallot was used with the three level of nitrogen (0kg/ha, 100kg/ha, 150kg/ha) and three intra-row spacing (10cm, 15cm, 20cm). The result of this field experiment indicated that, the interaction effect of 150gk/ha and 20cm spacing resulted highly significant plant height (30.33cm) (p<0.05). Nitrogen levels significantly affected the number of leaves per plant of shallot with the highest value (27.84cm) obtained from 100 kg N ha -1 ,so statistically significant(p<0.05). There was no significant effect of interaction between nitrogen and intra-row spacing on leave number of shallot. Significantly largest stem diameter 0.63cm (p<0.50) was obtained from intra-row spacing of 20cm. But there was no interaction effect of nitrogen and spacing on the stem diameter of shallot. There was no interaction effect of nitrogen fertilizer and spacing on the bulb diameter of shallot. No significant difference was obtained with the interaction effect of nitrogen and spacing on shallot bulb weight. An increased N dose to 100kgha -1 resulted in the increased yield of shallot bulbs to 30.2 tha -1 which was significantly different from 0kgha -1 and 150kgha -1 (p<0.05). From this finding the highest growth performance of plant which leads to increased yield could be using 150kgha -1 and spacing of 20cm.However the conclusive recommendation should be based on the results of repeated experiments. Keywords: Shallot, Nitrogen, Spacing, Plant height, Leave number

Effect of Nitrogen and Phosphorus Fertilizer Rates on Yield and Yield Components of Barley (&amp;lt;i&amp;gt;Hordeum Vugarae L.&amp;lt;/i&amp;gt;) Varieties at Damot Gale District, Wolaita Zone, Ethiopia

A field experiment was conducted at Damot Gale District, Wolaita Zone, SNNPRS to evaluate the response of barely varieties to nitrogen and phosphorus fertilizer application since the response varies from location to location due to several factors. Thus, there is a need to determine specific nitrogen and phosphorus fertilizer requirement of specific variety. The barley varieties (HB1370 and Shage) were used as test crop and the experiment contained factorial combination of four levels of N/P (0/0, 23/10, 46/20, 69/30 kg ha^-1) and was laid out in randomized complete block design with three replications. The results from this study indicated that nitrogen and phosphorus fertilizer showed no significant effect on number of days to heading while number of fertile tillers, total biomass and yield were significantly increased by application of nitrogen and phosphorus. However, the effects of nitrogen and phosphorus were significant (P < 0.05) on plant height, spike length, number of seeds per spike and grain yield. In general, grain yield tended to be higher under NP 69/30 kg ha^-1 treatment (2.02t/ha). In contrast, the lowest grain yield (0.86t/ha) was obtained from 0/0 NP treatment, although the interaction effects of nitrogen and phosphorus were significant on treatments with varieties and balanced amount of nitrogen and phosphorus. The future studies should articulate towards the studies involving more varieties, multi-location and additional rates of nitrogen and phosphorus applications, under diverse management practices such as research and farmer’s field’s conditions, which may facilitate fine-tuning of fertilizer recommendations.

Effects of Mineral Nitrogen and Phosphorus Fertilizers on Yield and Nutrient Utilization of Bread Wheat (Tritcum aestivum) on the Sandy Soils of Hawzen District, Northern Ethiopia

On-farm field experiments were conducted to assess the effects of nitrogen (N) and phosphorus (P) on yield, yield components, nutrients uptake and use efficiencies, protein content of bread wheat, residual soil nitrogen and phosphorus availability and economic return of fertilizer application. The locations of the experiments were in two nearby farmers' field at Hawzen district, Northern Ethiopia. Factorial combinations of five N levels (0, 46, 69, 92 and 138 kg N/ha) and four levels of P (0, 46, 69 and 92 kg P2O5/ha) were laid out in a randomized complete block design with three replications. Experimental Field 1 was relatively better in its soil fertility than experimental Field 2 especially in its phosphorus availability and cation exchange capacity (CEC). However, both fields were low in their total soil nitrogen content. Grain yield of wheat significantly increased by 46% and 15% in Field 1 and Field 2, respectively at nitrogen application rate of 46 kg N/ha than the control. Nitrogen fertilization increased straw yield significantly only in experimental Field 1. Phosphorus application at a rate of 46 kg P2O5/ha increased significantly grain and straw yields by 38 % and 46 %, respectively in Field 2 than control. It is also economical to apply phosphorus at this rate for such farmers’ field because the grain yield marginal rate of return was 179 %. Consistent results were observed on wheat nutrient uptakes and nutrient use efficiencies. Grain and straw yields of wheat were not significantly affected by the main effect of phosphorus application in Field 1. These results are consistent with the soil analysis result before planting where the soil phosphorus was found to be low in Field 1 and very low in Field 2. Previous management by the farmers may have influenced the soil fertility status. There were no interaction effects of nitrogen and phosphorus to affect wheat productivity and nutrient utilization in both fields. Future approach to soil fertility management should consider the past management history and should also be site specific based on soil fertility assessment. As a result, a combined application of 46 kg N/ha and 46 kg P2O5/ha are recommended to achieve sustainable bread wheat production on the sandy soils of Hawzen district. But in fields with higher initial soil phosphorus level, there is no need of applying phosphate fertilizer.

Interaction effect of nitrogen and potassium on growth and yield of carrot

The experiment was carried out to study the effects of three mulching practices viz., no mulch, water hyacinth mulch and polythene mulch, three levels of nitrogen viz., 0, 150 and 200 and three levels of potassium viz., 0, 200 and 250 kg/ha on the growth and yield of carrot. The yield and yield contributing characters of carrot were significantly influenced by the application of nitrogen and potassium fertilizers with mulching treated plot. The highest marketable yield (63.47 t/ha) was recorded from the treatment combination of black polythene mulch with 200 kg N/ha and 200 kg K/ha treated plot and the lowest (23.69 t/ha) from the control treatment (M0N0K0). But the benefit-cost ratio (BCR) was found maximum (5.60) in the treatment combination of water hyacinth mulch with 200 kg N/ha and 200 kg K/ha, and the lowest (2.54) in control treatment. Considering the above findings, water hyacinth mulch with the application of 200 kg N/ha and 200 kg K/ha appeared to be recommendable for carrot cultivation for the place where irrigation facility was not available.

Effect of nitrogen and phosphorus on damage of two-spotted spider mite (Tetranychus urticaeKoch) on bean (Phaseolus vulgarisL.)

In order to study the interaction effects of nitrogen and phosphorus in two-spotted spider mite (Tetranychus urticae Koch) on chiti bean, sadri variety, this experiment was conducted in 2012–13 at the Agricultural Research Station of Islamic Azad University, Arak Branch, Iran. A factorial experiment was arranged in randomized complete block design with three replications. Three levels of nitrogen (as urea 46% N) including no application (N1), 75 kg/ha (N2) and 150 kg/ha (N3) and three levels of phosphorus as di phosphate ammonium, no application (P1), 100 kg/ha (P2) and 200 kg/ha (P3) were used. Each day the number of deaths and the number of eggs was counted. In this paper, the life expectancy (LEx) of 1, 5, 15, 20, 25 and 30 days after infection has been studied. Results showed that nitrogen increased the establishment of the plant mite in days after infection and that phosphorus application in plants reduced life expectancy 20, 25 and 30 days after infection.