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Potassium is one of the major nutrients which is required for the plant growth and development. It is the most essential element in plants life as it increases root growth and contributes for water relations of plants making them to survive under drought conditions. Potassium is critically needed for maintaining water relations of plant, activating enzymes, supporting photosynthetic systems, translocating sugars and starch out of the leaves. The plants take up potassium in ionic form (K+).
The uptakes of potassium are affected by the soil and environmental factors. It is mobile in the plant and so the young plants take up potassium efficiently than the mature plants. The major role of potassium is that it is essential for the growth of root and stomata opening and closing under water stress condition. The plant root take up potassium at high pH with acidic soil. The potassium is also needed for the development of reproductive organs of plants.
The deficiency of potassium first appears on the lower leaves and it reduced the yield crops and quality of fruits. In horticulture crops the fruit size, yields, fruit color, shipping quality and shelf life of fruit are increased by application of potassium fertilizer in adequate amount. The uptake of potassium depends upon many factors which related to the plants. At vegetative stage of plants the uptake of potassium fertilizer occurs which showed that potassium fertilization had an effect on some crop quality attribute. The potassium is applied in soil through manures and through the fertilizers. In the soil the potassium are either available to the plant or leach down in the soil or not available to the plants. The overall cycle of potassium in soil are given below.
The water stress or drought is an important phenomenon which affects the crops and reduced the growth as well as yield of crops. Now a day the drought is one of the most important problems in Pakistan. The 70 per cent of the farmer of Pakistan are depends upon the agriculture. Due the shortage of water or unavailable of water the agriculture sector are affected and ultimately the farmers of Pakistan are affected. Another major problem of the farmers of Pakistan is that, they are not aware about the role of potassium in plants and so they cannot use the potassium in their soil. There are 16 essential nutrients required for the plats growth and development. The potassium is one of the major nutrients after nitrogen and phosphorus. These three nutrients NPK are essential for the growth of plants. The role of potassium in plants is that potassium in addition to regulation of stomata in photosynthesis and transpiration such as maintain of plant turgor, photophosphorylation, activation of enzyme and transportation of photo assimilates.
Under drought condition the nutrients are not available to the plants, so that the growth of plant is affected. For this problem the foliar application of potassium is an essential to mitigate the drought and improve the growth of plant under water stress condition. Under the drought condition, the plants take up foliar potassium through cuticles of leaves and plants withstand against drought. The potassium protects the structure of chloroplast and also protects the plant against cellular damage by reactive oxygen species under drought condition. The qualities of fruits are enhanced by the foliar application of potassium than soil application of potassium. Therefore, under the water shortage or drought condition the foliar application of potassium mitigates the drought and improves growth as well as yield of crop plants. The farmers of Pakistan use adequate amount of potassium in their soil and also use foliar potassium as a supplement for enhancing the growth and yield as well as quality of plants.