Drought problems and its solution
Under a month of dry and hot spell, Kuala Lumpur has reached the second highest temperature ever recorded (38? C) on Tuesday, 4th of March. Prolonged dry season with below average precipitation is the natural cause for drought. The state government has taken a right action by implementing water rationing on two days interval at affected areas. Although water rationing can help to conserve water in the dams, it could not solve drought problems forever.
Severe drought brings greatest impact on agricultural activities because water scarcity account for 70% of potential yield loses worldwide (Boyer, 1982). Biotechnology could be a permanent solution for this problem with the development of drought-tolerant crops. Plant genes that are related to stress tolerance have been isolated initially from Arabidopsis and introduced to several crop plants through genetic engineering. For example, ERA1 gene that encodes for the ? -subunit of Arabidopsis farnesyltransferase which involves the regulation of ABA.
In a studies carried out by Wang and his colleagues (2005), transgenic Brassica napus (Canola) carrying an ERA1 antisense construct driven by a drought-inducible rd29A promoter was compared with non-transgenic control in a field trial to examine the effectiveness of artificial stress-tolerant gene in crop plants. Interestingly, the results showed that transgenic canola has increased sensitivity to ABA and in the same time, reduced stomatal conductance and water transpiration under drought stress conditions (Wang et al., 2005). Transgenic plants are able to provide higher yields compared to the conventional species under water stress and still able to perform on par with non-transgenic plants in conditions of sufficient water, demonstrating that this new technology has no yield drag. Even though drought tolerant crops sounds like a foolproof plan, it is impossible for a plant to grow without a single drop of water. Alternative source of water must be obtained in order to survive during prolonged drought.
Desalination of sea water into potable water can be done by using the principle of osmosis. First, sea water is stored in one chamber and another chamber filled with a concentrated solution of a soluble salt, with both chambers separated by a semipermeable membrane. Water will diffuse into the concentrated salt solution, and then the solution will be stored in a third chamber, where the soluble salt in the solution is precipitated, leaving fresh water behind (Frank, 1972). Cloud seeding is another way to obtain water during droughts.
Powdered silver iodide and dry ice is a common agent used to seed clouds, they supercool water molecules in the clouds forming tiny ice crystals, these crystals grow at the expense of surrounding cloud moisture and eventually fall through the cloud to form rain droplets (Dennis, 1980). The severity of drought must be monitored in order to take appropriate counter measures. The Palmer Drought Severity Index (PDSI) has been the standard for measuring the duration of drought in many countries.