Artech Journal of Research Studies in Agricultural Sciences (AJRSAS) Volume, 1, Issue 1, 2018, Pages: 12-18 ISSN: 2523-5494 Impact of K + Application and Water Availability on Accumulation of Compatible Solutes and Growth of Brassica napus 1 Murad Ali, 1 Naveedullah, 2 Mushtaq Ahmad and 3 Muhammad Ali 1 Department of Water Management, The University of Agriculture Peshawar, Khyber Pakhtunkhwa, Pakistan 2 Department of Civil Engineering, Universiti Tenaga Nasional Malaysia Putrajaya Campus, Selangor, Malaysia 3 Department of Agricultural Extension, PMAS-Arid Agriculture University, Rawalpindi, Pakistan Abstract: The purpose of the study was to investigate the drought effects on canola. The performance of six canola genotypes was determined by measuring the proline, sugar, Relative Water Content (RWC), shoot fresh weight, shoot dry weight and plant height. At 100% irrigation, maximum shoot proline (3.22 µmol g 1 FW) and sugar content (7.16 mg g 1 FW) were obtained in Vanguard and Westar, respectively at 120 kg ha 1 K application. Similarly, maximum RWC (88.34%), shoot fresh weight (35.92 g/plant), shoot dry weight (15.44 g/plant) and plant height (43.10 cm) were obtained in Westar at 60 kg ha 1 K applications. K + application partially improved the different parameters under water stress conditions. Consequently, 60% irrigation water is applied, maximum proline content (8.95 µmol g 1 FW) and sugar content (16.37 mg g 1 DW) were obtained in Westar at 120 and 60 kg ha 1 K application. The maximum RWC (75.81%), shoot fresh (24.98 g/plant) and dry weight (10.74 g/plant) were obtained in Rainbow at 120 kg ha 1 K application. Similarly, maximum plant height (29.90 cm) was noted in Legend at 120 kg ha 1 K application. Study concluded that K + application successfully mitigated some of the adverse effect of drought stress and Rainbow was recommended for plantation in the limited water environment after supplementation with 120 kg ha 1 K. Key words: Drought, potassium, canola, proline, sugar, growth rate INTRODUCTION The different environmental stresses are a major threat to ensuring food supply to expanding world population. Drought stress is one of the most important limiting factors for growth and yield of crop which affects 40-60% of world agricultural land (Bray et al., 2000; Reddy et al., 2004). Being sessile in nature, plants have developed an elaborate mechanism to adapt to and withstand drought stress conditions. Canola or mustard is an important oilseed crop of Pakistan mainly grown in rain fed areas, where water availability is one of the important limiting factors affecting plant growth and development. It is generally considered to be susceptible to water scarcity, especially at the reproductive stage. The plants productivity depends on the photosynthetic fixation of carbon which is dependent on adequate supply of water and mineral nutrients from the soil. Thus, beside breeding tolerant genotypes, agronomic management is an important component of the crop production strategy to achieve an economic yield when water is limiting. Understanding the plants mechanism to tolerate or adapt to drought stress conditions can play a major role in improving crop production. A reduction in water loss and leaf growth under water deficit is attributed to the root sourced signals which are transported to the leaves via xylem vessels. Furthermore, different nutrient elements are also important signaling molecules playing important roles in stress perception and controlling downstream responses (Schachtman and Goodger, 2008). Exposure to water deficit results in increased formation of the Reactive Oxygen Species (ROS) because of the metabolic dysfunction, decrease in transpiration and CO 2 availability for photosynthesis (Karpinski et al., 1997; Smirnoff, 1993). Beside damage to all the major biological molecules, increase in steady state level of the ROS also plays important role in intracellular redox sensing, activation of antioxidant resistance mechanisms and other adaptive processes (Asada, 2006; Karpinski et al., 1997; Smirnoff, 1993). The extent to which plants can minimize increase in ROS steady state and water relation determines the degree of resistance to water stress. Corresponding Author: Murad Ali, Department of Water Management, The University of Agriculture Peshawar, Khyber Pakhtunkhwa, Pakistan Citation: Ali M., Naveedullah, M. Ahmad and M. Ali, 2018. Impact of K + application and water availability on accumulation of compatible solutes and growth of Brassica napus. Artech. J. Res. Stud. Agric. Sci., 1: 12-18. © Artech Journals