Wheat is the most important crop of world. In Pakistan too, wheat is the major staple food crop that fulfills about 95% of the food requirements of the country. Water is absolute necessity for proper functioning of all the living organisms on this planet. Water is the most important factor that is necessary for proper growth, balanced development and higher yield of all crops including wheat.
Improving irrigation efficiency for wheat
By Muhammad Amjad Ali
Regular and proper quantification of irrigation water is essential to sustain crop productivity. Irrigation requirements vary with stored moisture, effective rainfall, and the efficiency with which water is applied. However, the amount and timing of irrigation had an important effect on grain yield. Increasing the irrigation efficiency is a key area to optimize crop production with limited and dwindling water supplies.
Wheat is the most important crop of world. In Pakistan too, wheat is the major staple food crop that fulfills about 95% of the food requirements of the country. Water is absolute necessity for proper functioning of all the living organisms on this planet. Water is the most important factor that is necessary for proper growth, balanced development and higher yield of all crops including wheat.
To fulfill this obligation of providing adequate food for human being and their livestock, the agricultural scientists and researchers find ways to utilize all the natural resources efficiently, including water for crop production. Greater efforts are needed to increase water use efficiently in crop production due to the recent drought and the fact that fresh water is becoming scarcer and scarcer as well as costlier and costlier day by day. In this context irrigation management in wheat is of utmost significance because this crop has to feed whole the nation.
In addition, farmers are not aware of actual crop water requirements, and irrigation-scheduling practices are still largely based on the amount of water available with the farmers and the situation of the farm. Farmers tend to over irrigate to cover the unleveled fields. They should have the knowledge of water management practices and should schedule the irrigation according to the water requirements of the crop.
The water management technologies like efficient irrigation methods including laser leveling, raised bed plant, rainwater harvesting and water course lining could be the base of an efficient irrigation system in wheat. Efforts should also to be made by the farmers for efficient conveyance and application of pumped groundwater. Moreover, genetically improved cultivars with low water requirements could also be a valuable tool for saving irrigation water and increasing water use efficiency.
Wheat, which grows well under dry land conditions, and normally can mature with 4 to 6 irrigations. Although, the crop responds to supplemental irrigation, but careful irrigation management is important to produce consistently high yields with minimum costs particularly during period of water shortage at critical stages. To obtain good wheat crop irrigations at critical stages of crop growth be ensured viz.,
• 1st irrigation 35-45 days after sowing
• 2nd irrigation at tillering stage
• 3rd irrigation at boot stage.
• 4th irrigation at dough stage of grain formation.
Irrigation efficiency can be improved by adopting the principle, when and where. Water should be applied according to the crop needs. There are three growth stages of critical timing of irrigation, tillering stage, booting stage and heading stage or dough stage of grain formation. In case, any of these critical growth stages go without irrigation during the lifecycle of a crop, and it results in significant reduction in crop production.
Tillering is a critical stage in the development of wheat crop. Water shortage at this stage will result in less number of tillers per plant. At this stage crop plant needs moisture for the root development and elongation resulting in high number of tillers which in turn will result in high productivity of the crop.
Whenever there is low rainfall and irrigation water supply is limited, the critical periods for water deficit starts. When the plants are some 15 cm tall, just completing tillering and just starting elongation, at this stage irrigation should be applied. However; slight water deficits in the vegetative period may have little effect on crop development or may even somewhat hasten maturation. Wheat has the ability to form additional tillers when heavy water stress during the late vegetative period is followed by heavy water application.
Flowering period is the most sensitive to water deficit. Pollen formation and fertilization can be seriously affected under heavy water stress and during the time of head development and flowering water shortage will reduce the number of heads per plant, head length and number of grains per head. At the time of flowering root growth may be very much reduced and may even cease and considerable damage can be caused in this period.
The loss in yield due to water deficits during the flowering period cannot be recovered by providing adequate water supply during the later growth periods. Water deficit during the yield formation period results in reduced grain weight and hot, dry and strong wind in combination with a water deficit during this period causes shriveling of grain.
During the ripening period a drying-off period is often induced by discontinuing irrigations and water deficit during this period only has a slight effect on yield. Continuous drought and deficient rains cause tremendous losses to farmers
However, there is need to ensure irrigation supply at these critical stages of wheat to obtain maximum potential of the crop, otherwise improper irrigation management may become a limiting input influencing yield, returns, and crop quality. To cope with water shortage, there is necessary;
• A regular supply of irrigation water is essential to sustain crop productivity.
• Complete organization of water sector institutions through mergers.
• Economic utilization of water resources.
• Procurement of additional storage for crops round the year.
• Building storage to overcome droughts and to develop comprehensive water and hydro resource policy are necessary.
