No abstract

This experiment was conducted at the Demonstration Farm of the Faculty of Agriculture University of Khartoum at Shambat, Sudan, in 2016. The aim of the experiment was to study the effect of nitrogen and potassium fertilization on growth, yield and sugar content of two genotypes of sweet sorghum (Sorghum bicolor L. Moench). The treatments consisted of three levels of nitrogen (0; 50 and 100 kg N/Fed), potassium (0; 50 and 100 kg K/Fed) and two sweet sorghum genotypes;G1, RNF 1107 white colored seeds from El Gazira Aba and G2, El Banjadeed, black colored seeds from Kordofan. The experiment was arranged in a randomized complete block design with three replications. Studied parameters were plant height, number of leaves, leaf area, stem diameter, plant, leaf, stem and head fresh weights, baggasse and juice weights. The results showed that nitrogen application had a significant (P≤0.05) effect on plant height, number of leaves per plant, leaf area, stem diameter, plant and leaves' fresh weight, baggasse and juice weights. Potassium application affected plant height significantly (P≤0.05) but had no significant (P≤0.05) effect on number of leaves per plant, leaf area and stem diameter. Also potassium application had no significant effect on all studied yield parameters. The results indicated significant (P≤0.05) differences for most interactions. G2 showed better performance than G1 for plant height, leaf number, leaf area, stem diameter and yield parameters at N1K1

The objective of this work was to study K efficiency ofdifferent crops and determine the plant parameters affecting it. The studywas carried out using 14 different crops and cultivars grown on a sandysoil rich in humus, with two potassium fertilisation levels undercontrolled conditions. The studied crops showed different K efficiencyreflected in different dry matter yield production in unfertilised relative tofertilised treatments. All crops had, at low K supply, less than optimum Kconcentration in dry matter, indicating that the soil K concentration didnot meet the K requirement of the plants. Thus, the ability to produce highdry matter yield indicated superior adaptability to K deficiency. Theefficiency mechanisms employed by the different crops were low shootgrowth rate and/or high root length - shoot weight ratio and a high uptakerate per unit root, i.e. the influx, or low internal K requirement. Cropswith high influx had higher calculated concentration gradients, since theycaused further decrease of the concentration at the root surface. As such,they were able to create steeper concentration gradients between bulk soilsolution and root surface. This resulted in higher diffusive flux to theroots.

A field experiment was conducted for two consecutive seasons during 2010/2011 and 2011/2012 on the Demonstration Farm of the Faulty of Agriculture, University of Kassala at New Half. Nitrogen use efficiencies (i.e. agronomic AE, internal IE, physiological PE and recovery RE) and grain protein content were investigated at different level of watering regimes and organic manure application of wheat (Triticum aestivum L). The watering regime treatments were irrigation every 7, 14 and 21 days, and the nitrogen fertilizer levels were zero, 43, 86 kg N ha-1 without or with 4 tons of chicken manure ha-1. Frequent irrigation, addition of high N level and organic manure significantly increased AE, IE, PE, RE and grain protein content compared to their respective treatments. Mixing of organic manure and nitrogen fertilizer increased AE, IE and RE but resulted in a slightly increase in PE than both treatments when they were added solely. Further, the magnitude of organic manure on AE, IE, RE and grain protein content was significantly greater under normal watering regime. Wheat plants under optimum conditions (frequent watering, high N level plus organic manure) used N, as indicated by AE, PE, IE and RE, more efficiently than under other treatment combination.

The aim of this study was to compare simulated and actual Kuptake by three crops, under different K concentrations in the soilsolution, in order to try to explain the underlying mechanisms of nutrientuptake by these crops. In 2002, wheat (Triticum aestivum L. cv. Star),barley (Hordeum vulgare L. cv. Madras) and sugar beet (Beta vulgaris L.cv. C+ T) were grown on a sandy clay loam, with various Kconcentrations in soil solution, in the growth chamber at the Institute ofAgricultural Chemistry, University of Goettingen, Germany. Data werecollected on K transport in soil and uptake by the three crops and used forsimulation by a mechanistic model which encompasses uptake by roothairs as well. To quantify the significance of single soil and plantparameters for nutrient uptake, a sensitivity analysis was carried out.Under sufficient K in the soil solution, where transport was not limitinguptake, the model predicted the actual K uptake correctly. At deficient Kconcentrations, the model over-predicted the K uptake by both wheat andbarley but under-predicted that of sugar beet. The calculatedconcentration profiles around the roots showed that for cereals wrongvalues of the uptake kinetics caused the over-prediction of K uptake,whereas for sugar beet some processes more than was considered by themodel took place.