RESPONSE OF ONION GROWTH AND YIELD GROWN IN SOILS OF SEMI-ARID REGIONS TO FOLIAR APPLICATION OF IRON UNDER WATER STRESS CONDITIONS

Abstract

Iron (Fe) is one of the major micronutrient crucial for plant growth, yield and quality. A field experiment was conducted in Fallujah, Iraq during the autumn season in 2019 to study the effects of foliar application of iron and irrigation levels on growth characteristics and yield of onion (Allium cepa L.). A two-factorial experiment arranged as a randomized complete block design with three replications was conducted in loamy sand soil. The two factors were water stress (50, 75, and 100% consumptive use of water) and iron concentrations (0, 100 and 200 mg L–1). The results show a significant decrease in plant height, number of bulbs, total chlorophyll content, dry mass, iron content in the leaves, the average weight of bulbs and total yield of bulbs by reducing irrigation levels from 100 to 50% of the water supply. Application of iron by foliar spraying significantly increased most of the aforementioned traits. The interactions between iron and irrigation levels were significant in most of the measured traits. The interaction between 100% water supply and 100 mg L–1 of iron achieved the highest total yield value (4 332 Mg ha–1) while the combination of 75% of water supply and 100 mg L–1 of iron gave the highest value of water use efficiency (84.7%).