Intercropping with grasses helps to reduce iron chlorosis in olive

Abstract

Grasses are more efficient than dicots in acquiring Fe from calcareous soils. We studied whether intercropping with grasses alleviates Fe chlorosis in olive and whether the effect persists in succeeding dicot crops. Three different pot experiments were conducted. In the first, olive plants were intercropped with 6 different grass species (purple false brome, annual ryegrass, compact brome, goatgrass, barley and red fescue); in the second, the two species best performing in the previous experiment were studied in various calcareous soils and; in the third, chickpea and peanut were grown in pots previously used to cultivate the two grasses. Intercropping with purple false brome and barley increased leaf chlorophyll concentrations and/or boosted growth of olive trees on three different calcareous soils. Olive growth was adversely affected by intercropping in one soil as a result of competition for water. Intercropping increased Fe, Mn, Cu and Zn leaf contents in olive. Also, grass cropping generally raised available levels of soil Fe, Mn, Cu and Zn; this effect, however, resulted in no substantial alleviation of Fe chlorosis in succeeding chickpea or peanut crops. Intercropping with purple false brome and barley appears to be a promising remedy for Fe chlorosis in olive orchards affected by Fe chlorosis.