HABEN ASGEDOM1, AZIZA AJJOURI2, MATHIAS BECKER3
1International Centre for Agricultural Research in the Dry Areas (ICARDA), NRMP, Syria
2Aleppo University, Soil Fertility and Reclamation, Syria
3University of Bonn, Plant Nutrition in the Tropics and Subtropics, Germany
Low input production of barley on the predominantly calcareous soils in most countries of West Asia and North Africa is affected by drought and a low availability of P and Zn. Especially during the early growth stages, P and Zn deficiencies retards seedling growth, rendering the young plantlets particularly sensitive to the frequently encountered dry spells. Seed priming (imbibation in water and drying back to storage moisture until use) has been shown to improve crop establishment and, in some instances, to increase crop yields. While increased seedling vigour will improve barley establishment, possible benefits are likely to be limited when P and Zn are deficient. A promising variation of the priming concept is the seed treatment with solutions containing the limiting nutrient. A series of experiments was conducted in a phytotron in 2003 to develop a nutrient priming approach to foster the establishment of barley under marginal growing conditions. Seeds of the tradition barley cultivar Arabi aswad were soaked for 0-48 hours in water, and for 12 hours in solutions containing 5-500 mmol P, Zn and P+Zn and dried back to 12% moisture until further use. Seed were incubated at 10°C and germination was evaluated over a 6 to 8-day period. Additionally, growth and nutrient uptake of 4 week-old seedlings, grown at 25 and 100% field capacity in a typical Xerosol from Syrian were evaluated. Water priming for 12 hours with subsequent seed storage of up to 9 weeks increased germination rate from 65 to 95%, and advanced germination by up to three days compared to unprimed seeds. Addition of 10 mmol Zn and 50 mmol P to the priming solution increased the P and Zn content of the seeds without affecting germination. It furthermore significantly stimulated growth and P and Zn uptake by four week-old seedlings and improved the water use efficiency of drought-stressed plants by 44% above that of unprimed seeds. On-farm validation experiments in Syria are currently on"=going.
Keywords: Calcic xerosol, drought, Hordeum vulgare, nutrient priming, Syria