Regrowth potential of shoot and of roots of Rhodes grass (Chloris gayana Kunth) after defoliation.

Field and pot trials are described in which the effect of different lengths of precutting periods and of cutting intervals on regrowth of shoot and of root were studied in cv. Katambora Rhodes grass. The initial regrowth of the sward after a long (28 days) pre-cutting period was slower than after a short (7 days) pre-cutting period. The reduction of the residual leaf area index following the extension of the pre-cutting period, was associated with reduction in the number of tillers capable of regrowth after defoliation. Root weights decreased drastically following cutting when the initial root weight was high (long pre-cutting period), but little when the initial root weight was small (short pre-cutting period). The decrease in root weight lasted about 1 week after which it increased at more or less constant rate proportional to the increase of shoot weight irrespective of the length of the pre-cutting period. The lack of the capability of tillers to regrow after cutting was closely related with developmental stage of tillers. Since tillers of subtropical and tropical grasses have a tendency for early stem elongation, it was concluded that the relatively small number of sites available for regrowth in these grasses is the major deterrent for quick shoot growth of the sward after defoliation.