Comparative responses of Lolium perenne and Bothriochloa macra to temperature, moisture, fertility and defoliation

Abstract

Lolium perenne and Bothtriochloa macra were grown alone and In 1/1 mixtures In pot culture under molsture stress and moisture non-limiting conditions at both high and low levels of fertility, they were grown In three controlled environment cabinets operating at either 16/10°, 23/17° or 31/25°C, and defoliated to either 1 cm or 4 cm from the crown at each of two harvests.Temperature was the dormant factor differentiating the growth and competitive ability of both species Lolium grew best In the 16/10° and 23/17°C temperature regimes, production declining at 31/25° In contrast, Bothriochloa made very little growth a1 16/10° and responded linearly to measuring temperature. Both species responded similarly to increasing fertility and favourable moisture conditions, although such treatments had no effect on Bothriocochloa in the 16/10°C temperature regime Bothtriochloa was more tolerant of low fertility and moisture stress than was Loliurn, especially at 31/25° Lolium yielded more, and competed successfully with Bothtriochloa, only under conditions of high fertility and In the absence of moisture stress at temperatures up to 23/17°C Defoliation intensity had little effect on the total dry matter yields of either species, although it did influence the proportion of leaf to head and stem of Bothtriochloa. The likely implications of the results on the competitive relationships of the two species In the field In the Northern Tablelands environment of New South Wales are discussed