Triticum aestivum and Lolium multiflorum interaction during drought

A greenhouse experiment compared the vegetative growth in pure cultures and mixtures of winter Triticum aestivum cultivar 'Mit' and Lolium multiflorum cultivar 'Marshall' in continuously watered controls and drought treatments. Central L. multiflorum in pure culture 14 wk after planting produced more leaf area, tillers, and dry weights of stem and root than control T. aestivum in pure culture. The greater seed size, Larger initial leaf area, and height allowed T. aestivum to produce greater final leaf area and dry stem weight in control mixtures than L, multiflorum. Watering following drought shifted the relative performance of the two species in pure cultures and mixtures compared to controls. The ability of I: aestivum to maintain a greater leaf expansion rate during drought and a greater leaf area afterward than L, multiflorum allowed T. aestivum to attain greater growth than L, multiflorum in pure cultures exposed to temporary drought followed by watering. Conversely, drought and its relief enhanced the relative competitiveness of L. multiflorum compared to controls in mixtures with I: aestivum. During 4 wk of watering following the drought, L. multiflorum in mixtures grew vigorously and was similar to T. aestivum in all measures except in height and dry stem weight. Thus, L. multiflorum was similar in root growth with I aestivum in control and drought mixtures and had its aboveground competitiveness amplified by the cycle of drought and watering in this study There was no evidence of an allelopathic interaction between the two species.