| Response of wheat and triticale cultivars grown under
field conditions to drought stress Hassan I. SAYED college of Agriculture University of Riyadh, Riyadh, Saudi Arabia The life cycle of the wheat plant in the Arabian Peninsula covers the period from November to April, during which the rainfall is inconsistent and negligible. Crop yield depends primarily on the amount of moisture available during the growing season. In view of the limited water resources in the area, breeding for drought tolerance could save in the amount of consumed water or produce more yield for the same amount of water consumed. Few steps were suggested in breeding for drought stress (4). These are; (a) Careful evaluation of material for individual traits associated with drought resistance as well as for yield performance under stress conditions. (b) Intercrossing of cultivars with a number of these traits. (c) Subsequent selection, in the segregating generations, of lines combining these characteristics with high yields under stress. Although recent breeding efforts have resulted in high yielding cultivars under high fertility, most of these have generally yielded the same or sometimes even less than previously developed cultivars under severely stressed conditions (5). The objectives of this paper were; (a) To evaluate some high yielding cultivars for drought tolerance. (b) To identify some of the agronomic traits which relate to drought tolerance under the prevailing conditions. Materrals and Methods The experiment was conducted during the winter season of 1979-1980 in the College of Agriculture, Riyadh University Experimental Station near Riyadh, Saudi Arabia. The Experiment consisted of 14 bread wheat (Triticcum aestivwa L.), nine durum wheat (Triticum durum Desf.) and one triticale (X Triticosecale Wittmack) cultivars (Table 1). Three cultivars, Mexipak, Arz and Jori 69 were chosen since they are widely grown in the area. The rest of the genotypes were selected for their high yielding ability in national breeding programs of the region. The experimental design was a randomized complete block with four replications. Each replicate consisted of six rows, 2.5 m long and 30 cm apart. The seed rate was 100 kg/ha and fertilizers were applied at a rate of 100 kg/ha N and 50 kg/ha P2O5. The phosphorus and half of the nitrogen fertilizers were added two weeks after emergence, while the rest of nitrogen was applied four weeks later. The planting date was 29/12/1979, four weeks later than the recommended date in order to expose the plants to high temperatures late in the season thus pronouncing the effects of drought stress. |
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