Potato stands 4 th after wheat, rice and maize among the major food crops in Pakistan. It was grown on an area of 131.9 million hectare with 2622.3 thousands tons of production averaging 19.9 tons ha -1 during the year 2007 which was very low as compared to the yields of leading potato growing countries of the world. Potato is a short duration, high yielding and exhaustive tuberous crop. Balanced use of nutrients is essential for a sustainable productivity of crops. Nitrogen and phosphorus fertilizer are being used while ignoring potassium application which causes serious decrease in the status of K in soils of potato growing areas because K has great importance in improving quality and yield of potatoes. Potassium has a crucial role in higher productivity of potato tubers because it plays an important role in photosynthesis, regulation of opening and closing of stomata, favors high energy status which helps in timely and proper nutrients translocation and water uptake in plants. The potato growers in Pakistan follow different practices and techniques in different localities for higher yields in potatoes. Keeping in view, the existing management practices of potato growers in Pakistan, a research project of field studies comprising of four experiments, was designed for the selection of best source of potassium, time and application of fertilizer techniques, different levels of potassium to determine the effects of K on some physio-morphological features of the crop. A promising red potato cultivar “Desiree” was selected. The optimal recommended dose of potassium (125 kg ha -1 ) was supplied at the time of planting. Data of different qualitative and quantitative characteristics were collected under the Randomized Complete Block Design with three replications and analyzed by using standard statistical techniques. The experiment#1 was conducted in order to assess the impact of different organic and inorganic sources of potassium (i.e. FYM, SOP and MOP) for the evaluation of the best with 10 different combinations of treatments which were replicated thrice. The parameter like total emergence %age, No. of aerial stems plant - 1 , specific gravity and tuber dry matter %age were found statistically non-significant while, No. of leaves plant -1 , Plant height, No. of tuber plant -1 , Tuber weight plant -1 , Yield ha -1 TSS and tuber dry weight plant -1 , were observed significant and gave better in case of T 2 (SOP source). In some of the parameters like Tuber weight plant -1 , yield xvii ha -1 and tuber dry weight plant -1 , T 4 (1⁄2 from SOP+ 1⁄2 from FYM) were found equally effective with T 2 whereas, T 0 (control) performed worse. The experiment #2 comprised of 9 treatments with 3 replications. This experiment was undertaken to check the effects and proper time of potassium application methods. The parameters of total emergence %age, number of aerial stems plant -1 and number of tuber plant -1 were found statistically non-significant while, number of leaves plant -1 , plant height, number of tuber plant -1 , tuber weight plant -1 , yield ha -1 , TSS, specific gravity, tuber dry matter %age and tuber dry weight plant -1 were found significant with the supremacy of T 2 ( Full dose of SOP at the time of planting through placement method) with the conclusion that SOP was found superior to the other potassium sources in most of the aspects of growth and yield of potato crop. For the assessment the best level of K in order to the maximum growth and yield of potato, the experiment #3 was designed with 7 numbers of treatments and 3 replications. The parameters of total emergence %age, plant height, number of tuber plant -1 , tuber weight plant -1 , yield ha -1, TSS and tuber dry weight plant -1 were found statistically significant while, number of aerial stems plant -1 , number of leaves plant -1 , specific gravity and tuber dry matter %age were observed significant with the supremacy of T 3 (150 kg K 2 O ha -1 ) which was found the best for most of the aspects of study. An excessive dose of K 2 O up to 250 kg K 2 O ha -1 was found ineffective for vegetative and yield characteristics while the under dosing up to 100 kg K 2 O ha -1 was observed comparatively less effective. The experiment #4 was conducted for convenience of different physio- morphological and storage aspects of potato crop by applying FYM, SOP and MOP with 6 combinations of treatments and was replicated thrice. The data were collected on 5 fortnight intervals with effect from 30 to 90 days after planting. The agronomic parameters, like number of leaves, leaf area index, leaf area duration, crop growth rate, relative growth rate, net assimilation rate, stem length and diameter were observed significant for the treatments and the years with the superiority of T 4 ( 1⁄2 SOP + 1⁄2 FYM) followed by T 2 ( Full dose of SOP) while T 0 ( control) was found at the bottom. The physiological aspects such as chlorophyll contents, net photosynthesis rate, intra cellular CO 2 concentration, transpiration rate, stomatal conductance and water use efficiency were found statistically significant for the xviii treatments and the years with the best results from T 4 ( 1⁄2 SOP + 1⁄2 FYM)and T 2 (Full dose from SOP). The storage behavior was studied by keeping tubers at ambient and cold storage conditions. The results were gathered at 5 fortnight intervals with effect from 30 th days after storage. The data for the weight loss %age, sprouting %age, rotting % age, physiological disorders % age, starch contents % age, protein contents %age, reducing sugars and vit.C showed significant differences with the superiority of SOP alone or in combinations with FYM as compared to the other treatments while T 0 was observed at the bottom. The cold storage conditions were found better as compared to ambient conditions. For the physic-chemical characteristics like starch %age, protein, reducing sugars and vit.C, T 2 (Full dose from SOP) was again found effective as compared to the other variables of potassium applied for the study, in both conditions of storage.