The Effects of Crop Combination and Row Arrangement in the lntercropping of Lettuce, Favabean and Pea on Weed Biomass and Diversity and on Crop Yields

Abstract

ABSTRACT Lettuce, favabean and pea were grown as sole crops and as intercrops in all 3 paired combinations (ie. fava:lettuce, pea:lettuce, fava:pea) with 4 different row arrangements (ie. 1:1, 1:2, 2:1, 2:2) under weeded and unweeded conditions. The weed biomass and diversity, as measured by species richness, were recorded for all unweeded treatments. The crop yields and land equivalent ratios (LERs) were determined for all treatments. Weed biomass was significantly reduced compared to sole crops by intercrops of fava:lettuce in 1:1 and 2:2 row arrangements, by fava:pea in 1:1,1:2 and 2:1 row arrangements, but not by pea:lettuce in any row arrangement. Weed diversity was not significantly different compared to sole crops for all intercrop treatments. Yield reductions by weeds in the intercrops ranged from 23 to 40% for lettuce, from 19 to 42% for fava, and from 15 to 50% for pea. Yield reductions by weeds were dependent on crop combination and row arrangement, not necessarily weed biomass, and suggested t...