Written by Zahoor Ahmad*, Dr. Ejaz Ahmad Waraich, Muhammad Irfan Department of Crop Physiology University of Agriculture Faisalabad Pakistan
Cotton (Gossypium hirsutum L.), occupies a prominent position in the agriculture of Pakistan being the raw material for the textile industry, as well as the main source of locally produced cottonseed oil providing 60% oil of domestic needs. It accounts for 7.3% of the value added in agriculture and about 1.6% to GDP. In 2009 the cotton production was 14.5 percent less than the target of 14.11 million bales mainly due to the shortage of irrigation water, less use of fertilizer and attack of Cotton Leaf Curl Virus and mealy bug. Water stress is one of the major limitations to crop production in arid and semi-arid regions of the world. The reduced precipitation together with the higher evapotranspiration in these areas is expected to subject natural and agricultural vegetation to a greater risk of more severe and prolonged water stress. Even a temporary drought can cause substantial loss in crop yield. At the whole plant level the effect of stress is usually perceived as a decrease in photosynthesis and growth and is associated with alteration in carbon and nitrogen metabolism. The relative part of stomatal limitation of photosynthesis depends on the severity of water deficit. In Pakistan, more than 5.0 million ha of the total cropped area is rain fed, which is about 22% of the total cultivable land and drought is a major limiting factor for crop productivity in these areas. Water scarcity is also very common under irrigated conditions and crops face temporary water stress of varying degrees during the season. Worldwide agriculture has the biggest demand for water use and during 2000 total agriculture share of water use was 70%, as compared to 10% for domestic consumption and 20% for industry.
Potassium (K) is one of sixteen essential nutrients required for plant growth and reproduction. It isclassified as a macronutrient, as are nitrogen (N) and phosphorus (P). The chemical symbol forpotassium is "K." It is taken up by plants in its ionic form (K+). The word potassium translates from the Latin or German word, Kalium. The term "potash" comes from the colonial practice of burningwood in large pots and using the ashes as fertilizer and making soap, gunpowder and glass."Potash" is defined as K2O and is used to express the content of various fertilizer materialscontaining potassium, such as muriate of potash (KCl), sulfate of potash (K2SO4), double sulfate ofpotash and magnesium (K2SO4. 2MgSO4), and nitrate of potash (KNO3).
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