EFFECTS OF DROUGHT ON WINTER WHEAT YIELDS IN A SEMI-ARID REGION

Abderrahmani Belaid, Regional Meteorological Training Centre Oran/ University of Science and Technology of Oran, Algeria
Hadjel Mohamed, University of Science and Technology of Oran, Algeria
Dobbi Abdelmadjid, University of Ouargla, Algeria
Hassini Noureddine, University of Oran, Algeria

Abstract

The cultivation of wheat in arid regions is an economically risky undertaking, mainly of fluctuating rainfall distribution and alternative dry spells throughout the growing season. Statistical analysis previously carried out shows the rainfall season usually starts in December and ceases in April, the reason the wheat crop is planted during the month November/December and harvested during the month of June in the northern part of Algeria. Although the wheat is a relatively drought –resistant crop, it may be sensitive to the random effects of severe drought conditions. According to its occurrence during the cycle, drought may be decisive on the final production quantity and quality. This study is an attempt to estimate reductions in wheat yields caused by drought. Acting from soil-plant-atmosphere interactions, impact of water deficit on wheat yield can be estimated for each of the main growing stages. To lessen the effects of drought and maximize results, we adjusted better to the wheat growing season by selecting three useful sowing dates. A means of assessing the effects of drought on the yield of wheat is of considerable interest to agronomist in the prospect of climate change adaptation. The simulation was conducted in ten consecutive agricultural years (1989-1998), for three locations characterizing the semi-arid climate in north western Algeria, by using CROPWAT software which incorporates the distribution of rainfall over the growing season. The methods of calculating water needs of crops are mainly based on methods presented in the FAO bulletins of irrigation and drainage.The analysis of obtained results in semi-arid Mediterranean, particularly in the north-western Algeria, show that the total seasonal rainfall is insufficient to cover the water requirements of rain fed crops like winter cereals. On the other hand, the rainfall distribution over time favors during the development cycle, the occurrence of periods of water stress periods which the final yield. However, planting date suitably chosen provides, to some extent a more interesting biological itinerary, which subtracts the plant in such a climate hazard and dampens the reducing effects of drought.